Skeptical Science

2012 SkS Weekly Digest #5

Mon, 6 Feb 2012 15:29:44 EST

SkS Highlights

Kevin Trenberth's guest post, Check With Climate Scientists for Views on Climate is the response from a number of prominent climate scientsts to a letter signed by 16 scientists and engineers that was recently published in the Wall Street Journal. The "Gang of 16's" letter was also squarely addressed by Dana in The Latest Denialist Plea for Climate Change Inaction

Still Going Down the Up Escalator by Dana also garnered a lot of attention by commentors and other websites. MarkR's Measurements show Earth heating up, think tanks & newspapers disagree addressed denialist propaganda recently published in certain UK news outlets. The creative graphics embedded in the article also received attention by other websites.

Toon of the Week

H/T to Joe Romm's Climate Progress.

Issue of the Week

During the past 12 months approximately how many times have you used the icon buttons (Christy Crocks, etc. which are posted on the top of the left-hand column of this web page) to access one or more articles in a particular series? Do you believe these buttons serve a useful purpose? Would you like to see SkS add more topical buttons? If so, what buttons would you recommend be added?

The Week in Review

A complete listing of the articles posted on SkS during the past week.

Major Study of Ocean Acidification Helps Scientists Evaluate Effects of Atmospheric Carbon Dioxide on Marine Life by John Hartz

NASA scientists expect more rapid global warming in the very near future (part 2) by Rob Painting

Cool climate papers 2011 by Ari Jokimäki

Still Going Down the Up Escalator by Dana

Check With Climate Scientists for Views on Climate by Kevin Trenberth

Measurements show Earth heating up, think tanks & newspapers disagree by MarkR

Climate change policy: Oil's tipping point has passed by John Hartz

New research from last week 4/2012 by Ari Jokimäki

The Latest Denialist Plea for Climate Change Inaction by Dana

Coming Soon

A list of articles that are in the SkS pipeline. Most of these articles, but not necessarily all, will be posted during the week.

Global Sea Level Rise: Pothole To Speed Bump? (Rob Painting)
New research from last week 5/2012 (Ari Jokimäki)
Volcanic Influence on the Little Ice Age (Dana)
Michaels Misrepresents Nordhaus and Scientific Evidence in General (Alex C)
Climate and Pollen (Robert Way)
The Year After McLean - A Review of 2011 Global Temperatures (Dana)
Monckton Misrepresents - The Neverending Story (Dana, Alex C, & Tom Curtis)
The Independence of Global Warming on Residence Time of CO2 (Dikran Marsupial)

SkS in the News

Carbon Brief re-posted MarkR's witty graphics from Measurements show Earth heating up, think tanks & newspapers disagree.

SkS Spotlights

CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia's national science agency and one of the largest and most diverse research agencies in the world. To access the CSIRO homepage, click here.

In June, 2011, CSIRO published, Climate Change: Science and Solutions for Australia. This book provided the latest scientific knowledge on a series of climate change topics relevant to Australia and the world. It drew on peer-reviewed literature contributed to by thousands of researchers. To access this free eBook, click here.

Michaels Misrepresents Nordhaus and Scientific Evidence in General

Thu, 9 Feb 2012 01:07:08 EST

The Wall Street Journal’s 27 January 2012 climate change op-ed came under harsh and swift criticism for being signed by only two climate scientists and fourteen other non-climate scientists, criticism most notably demonstrated by a group of 38 climate scientists in a response letter that the Journal has agreed to publish (to its credit). Apparently this strong show from experts in the field has not stopped Dr. Patrick Michaels, though, from nailing his colors to the mast at Forbes, and both promoting misrepresentation of the research of another scientist - Professor William Nordhaus - and misinforming the public on the consensus of evidence in climate science.

Michaels continuing the misrepresentation of Dr. William Nordhaus

Michaels starts his opinion piece by first contradicting another op-ed that appeared in the New York Times, written by Andrew Revkin. In his piece, Revkin cites an email exchange that he had with Sterling Professor of Economics at Yale University, Dr. William Nordhaus. For some quick background info, the Wall Street Journal op-ed stated:

A recent study of a wide variety of policy options by Yale economist William Nordhaus showed that nearly the highest benefit-to-cost ratio is achieved for a policy that allows 50 more years of economic growth unimpeded by greenhouse gas controls.

Nordhaus said in his exchange with Revkin,

The piece completely misrepresented my work. My work has long taken the view that policies to slow global warming would have net economic benefits, in the trillions of dollars of present value. […] I have advocated a carbon tax for many years as the best way to attack the issue.

Now one would think that a researcher would be aware of what his own research says. Michaels does not think so though, and goes on to explain how the WSJ op-ed authors know more about Nordhaus’ work than the man himself does, as is allegedly demonstrated in Nordhaus' book, A Question of Balance: Weighing the Options on Global Warming Policies. In his book, Nordhaus details the 2007 results of the DICE (Dynamic Integrated model of the Climate and Economy) model, which is an economic model that compares the costs of climate damages and mitigation policies, from the perspective of economic growth theory. He summarizes this in his first chapter:

In this approach, economies make investments in capital, education, and technologies, thereby abstaining from consumption today, in order to increase consumption in the future. The DICE model extends this approach by including the “natural capital” of the climate system as an additional kind of capital stock. By devoting output to investments in natural capital through emissions reductions, reducing consumption today, economies prevent economically harmful climate change and thereby increase consumption possibilities in the future. (p. 7)

The model ran a baseline scenario in which no action is taken, and projected present-value costs of such a course of (in)action. Nordhaus then had it run several more simulations, which are based around various climate policies that economies could work to implement.

Michaels cites the 16 signatories (who had responded to this accusation of misrepresentation themselves), who in turn cited Table 5.3 in Nordhaus’ book (p. 89), which gives the foregone costs from each policy (relative to the baseline scenario) and implementation costs, and a ratio between the two. In order, the policies with the highest benefits/costs ratios are:

Rank	Climate policy option	Ratio of Benefits (relative to baseline) to Costs
1	Kyoto without USA	6.00
2	Limit to 2.5*pre-industrial CO₂ (700 ppm)	2.43
3	"Optimal" (most efficient, optimistic)	2.42
4	50-year wait	2.38

The ratio is about 2% less than a general proposed carbon reduction plan (2.5xCO₂), so there's not much of a difference between 50-year wait and carbon pricing policies (aside from the Kyoto agreement w/o USA involvement - this will be covered below, but Nordhaus starts to express his own conclusions of the Kyoto agreement likely being inefficient on page 17). It is not this ratio, however, that is the most important bit of data concerning this issue. The ratios are very similar, but what about the money actually saved? I could spend $1 to save $3 down the road, but I would much rather spend $10 to save $30. Indeed, Nordhaus had actually commented on this important aspect of climate policy in the first chapter of his book:

The results of this book emphatically point to the importance of designing cost-effective policies and avoiding inefficient policies. The term “cost-effective” denotes an approach that achieves a given objective at minimum cost. (p. 17)

Nordhaus also, earlier, gives a sneak peak at the quantitative results of the model runs:

The efficient climate-change policy would be relatively inexpensive and would have a substantial impact on long-run climate change. The net present-value global benefit of the optimal policy is $3 trillion relative to no controls. This total involves $2 trillion of abatement costs and $5 trillion of reduced climatic damages. Note that even after the optimal policy has been taken, there will still be substantial residual damages from climate change, which we estimate to be $17 trillion.

[...]

We found that for most of the climatic-limits cases, the net value of the policy is close to that of the optimal case. (p. 15)

So, how much do the benefits actually outweigh the costs? Here is that list, derived from numbers in Figure 5.3, but also observable in terms of total cost of each plan in Table 5.1 (p. 83):

Rank	Climate policy option	Savings = Benefits - Costs [Trillions USD (2005)]
1	Limit to 2.5*pre-industrial CO₂ (700 ppm)	3.08
2	"Optimal"	3.07
3	Limit to 3˚C	3.02
4	Limit to 2.0*pre-industrial CO₂ (560 ppm)	2.67
5	50-year wait	2.14
...	...	...
10	Kyoto without USA	0.10

Not only did the 50-year wait option fall short of a given carbon pricing plan ratio-wise when it came to benefits v. costs, it falls in fifth place amongst the list of policy options in net savings, almost a full trillion dollars less in savings.

Nordhaus himself states in his book "[o]ur modeling results point to the importance of near-universal participation in programs to reduce greenhouse gases," (p. 19). While not being wrong about their statements about the near-ideal ratio of benefits-to-costs of a 50-year wait policy, the 16 signatories were very wrong about their interpretation and presentation of Nordhaus' results, even though the results were explicitly stated in the book. That is careless. That they would maintain that they correctly represented Nordhaus’ own conclusions, even after he himself insisted they did not, is entirely unacceptable in a meaningful scientific debate; and Michaels should should not have so willingly supported these claims without first double-checking their validity.

When in doubt, turn to experts

In addition to misreporting Nordhaus’ research, Michaels decided to attempt to address points brought up in Trenberth et al’s 38-signatory response letter. Dr. Trenberth analogized the commentary of the non-climate scientists in the WSJ op-ed on climate science issues to your dentist attempting to diagnose your heart condition. While both fields fall under the biomedical field of studies, neither is a specialist in the others’ field. This point is lost on Michaels though, who thinks that climate science can be generalized as “nothing more than applied physics.” While this denigration of the field only helps to elaborate on Trenberth’s analogy (cardiology and dentistry are, after all, both fields of medical study!), readers would be wary to not fall for this red herring. When faced with an issue, we consult experts in the relevant field; and when non-experts publish claims that greatly diverge from the consensus of evidence and experts in the field, we face those claims with high skepticism.

Climate sensitivity misinformation

Michaels goes on to defend Dr. Richard Lindzen’s views on low climate sensitivity from Trenberth’s likening to extreme views in other fields, such as the idea that AIDS is not caused by HIV or that smoking does not cause cancer (analogies which Michaels thinks make Trenberth as a dentist commenting on cardiology… even though the contrary to those views indeed are the positions of the experts in those fields). Climate sensitivity is the climate's temperature response to a given radiative forcing (˚C/W/m^2), and is typically expressed as the temperature response relative to the forcing from a doubling of CO₂ (2xCO₂). Lindzen has consistently promoted a low climate sensitviity, as low as <1˚C/2xCO₂. However, contrary to Michaels' assertion, the consensus of evidence does not support a low sensitivity, but instead the IPCC’s mean estimate of 3˚C/2xCO₂.

Figure 1: Distributions and ranges for climate sensitivity from different lines of evidence. The circle indicates the most likely value. The thin colored bars indicate very likely value (more than 90% probability). The thicker colored bars indicate likely values (more than 66% probability). Dashed lines indicate no robust constraint on an upper bound. The IPCC likely range (2 to 4.5°C) is indicated by the vertical blue shaded regions. Adapted from Knutti and Hegerl (2008).

We have additionally covered at SkS, on multiple occasions (such as here, here, and here), why Lindzen’s views on climate sensitivity are appropriately labeled “extreme.”

The Earth is still heating up

Michaels spreads further misinformation in his response to Trenberth’s claim that warming has not abated in the past decade (as was claimed in the original WSJ op-ed). Both Michaels and the 16 WSJ signatories make the mistake that many “skeptics” do, which is to focus on short term time spans and ignore the underlying trend: trying to walk down an up escalator.

Figure 2: Still Going Down the Up Escalator (NOAA NCDC Land-Ocean Data)

There are further problems with Michaels’ article on this issue, though.

Adding trends to data helps us see the trends

For starters, we actually do have surface temperature records, not just satellite data from which surface temperatures can be estimated. NASA’s GISTEMP is perhaps the most comprehensive of the surface records, as it includes regions excluded by others (such as the polar Arctic, which is left out in HadCRUT3 for instance; the polar Arctic is also not included in the satellite data), and using the time interval Michaels chose, since 1997 we have seen warming of ~0.16˚C. That’s simply not zero. Even when we apply a trend to the UAH satellite data over the 1997-present time period, which Michaels for some reason did not do, we see that the lower troposphere has warmed by about 0.145˚C, again not zero.

Accounting for variation

Furthermore, both the surface and troposphere temperature estimates are subject to the effects of exogenous factors – such as ENSO, or the solar cycle – that do not have a long term contribution to the temperature trend but which can affect short term data analysis (this is why it is generally not a good idea to pick small time frames when looking for trends). When these exogenous factors are accounted for, as Foster and Rahmstorf 2011 did, we see a continuation of the warming trend from the past several decades.

Figure 3: Foster and Rahmstorf (2011) - Figure 5 in-paper

Heat accumulating elsewhere, too

Of course, the planet is not only defined by the atmosphere. Energy has not only been accumulating in the atmosphere, but also in other heat sinks as well, namely the ocean. In fact, Trenberth et al note as much in their letter:

And computer models have recently shown that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean.

This aspect of the climatic system, however, goes unmentioned in Michaels’ article. We indeed have confirmation of such heat accumulation, especially of accumulation in the very deep ocean (1500 meters) as shown by von Schuckmann and Le Traon 2011.

Figure 4: von Schuckmann and Le Traon (2011) - Figure 5 (middle) in-paper

What we see in the spread of evidence is that the Earth continues to warm up, and that claims that the Earth has stopped warming since “year X” are without foundation.

The importance of addressing misinformation

The public deserves to be well informed of the accepted science in any field. Climate scientists like Trenberth et al perform a service to the public (not to mention the credibility of their own profession) by addressing misinformation as promulgated in the WSJ op-ed, and by standing up for the consensus of evidence. The consensus of evidence tells us that global warming is happening, that it is now almost entirely human-driven and that it will cost us down the road unless we start to take action now to address it. Just like we need our cardiologists to tell us when our heart is at risk, we need our climate scientists to step up and speak out. It is telling how Michaels feels about such confrontation from his concluding statement:

All of which goes to show that when climate scientists engage each other, the waste heat probably does contribute to an increment of global warming.

It’s not quite often that we hear from “skeptics” that climate scientists shouldn’t engage each other, or other people (it's shocking to think that such a statement came from a climate scientist in the first place). However, as long as “skeptics” continue to spread misinformation, especially when they are not experts in the field, that is exactly what they should expect and be prepared for. And as long as Dr. Michaels chooses to continue misinforming others himself - and more reprehensibly, to continue to misrepresent the research of other scientists - he too should expect to be called out by people paying attention.

Global Sea Level Rise: Pothole To Speed Bump?

Tue, 7 Feb 2012 02:48:19 EST

As indicated in a press release from the NASA Jet Propulsion Lab last year, short-term trends in global sea level rise are greatly affected by temporary exchanges of water mass between the land surface and ocean - creating 'potholes' and 'speed bumps' in the sea level record. This a consequence of changes in precipitation (rainfall & snow) resulting from the El Niño-Southern Oscillation (ENSO).

During La Niña the sea surface is cooler-than-normal and rainfall is concentrated over land, which leads to a temporary fall in global sea level. With El Niño the surface of the tropical Pacific Ocean becomes warmer-than-normal, and rainfall gets concentrated over the ocean. This, combined with the drainage of water from land, causes a temporary spike in global sea level.

ENSO is principally responsible for the large year-to-year fluctuations evident in the global sea level record, but neither of these two phenomena (El Niño/La Niña) alter the long-term sea level rise which results from the melting of land-based ice, and the thermal expansion of the oceans as they warm. They do, however, cause sufficient 'noise' to obscure the long-term sea level rise when viewed at short intervals.

In the last two years two back-to-back La Niña have temporarily lowered sea level, but La Niña appears to have weakened in recent months and accordingly we would expect an uptick in sea level rise as conditions move closer to neutral. A quick look at AVISO confirms this, see Figure 1.

Figure 1 - The reference mean sea level since January 1993 (left) is calculated after removing the annual and semi-annual signals. A 2-month filter is applied to the blue points, while a 6-month filter is used on the red curve. By applying the postglacial rebound correction (-0.3 mm/year), the rise in mean sea level has thus been estimated as 3.18 mm/year. Image from AVISO.

Rather than focusing on the potholes, as the skeptics do, one needs to consider the broader picture. That means factoring in the speed bumps too. See figure 2.

Figure 2 - University of Colorado global mean sea level data with a 12-month running average, and short-term declines. This animation does not include the latest sea level updates indicated in figure 1.

What happens to global sea level rise over the short-term will depend on which aspect of ENSO develops in the tropical Pacific this year. Whatever the case may be, global sea level rise will continue over the long-term because of the accelerating melt of land-based ice and continued warming of the oceans.

Still Going Down the Up Escalator

Fri, 3 Feb 2012 15:50:38 EST

The Escalator, originally created as a simple debunking to the myth "Global warming stopped in [insert date]", turned out to be a very popular graphic. Going Down the Up Escalator, Part 1 recently surpassed 20,000 pageviews, Part 2 has an additional 4,000+ views, and the graphic itself has been used countless times in other blogs and media articles. Due to its popularity, we have added a link to The Escalator in the right margin of the page, and it also has its own short URL, sks.to/escalator.

The popularity of the graphic is probably due to the fact that (1) it's a simple, stand-alone debunking of the "global warming stopped" myth, and (2) that particular myth has become so popular amongst climate denialists. As The Escalator clearly illustrates, it's easy to cherry pick convenient start and end points to obtain whatever short-term trend one desires, but the long-term human-caused global warming trend is quite clear underneath the short-term noise.

The original Escalator was based on the Berkeley Earth Surface Temperature (BEST) data, which incorporates more temperature station data than any other data set, but is limited to land-only data; additionally the record terminates in early 2010. We originally created the graphic in response to the specific myth that the BEST data showed that global warming had stopped.

It is interesting to apply the same analysis to a current global (land-ocean) temperature record to determine whether short term trends in the global data can be equally misleading. A global version of the Escalator graphic has therefore been prepared using the NOAA NCDC global (land and ocean combined) data through December 2011 (Figure 1).

Figure 1: Short-term cooling trends from Jan '70 to Nov '77, Nov '77 to Nov '86, Sep '87 to Nov '96, Mar '97 to Oct '02, and Oct '02 to Dec '11 (blue) vs. the 42-year warming trend (Jan '70 to Dec '11; red) using NOAA NCDC land-ocean data.

The Predictable Attacks

On 31 January 2012, John Cook emailed me about several recent uses of The Escalator, including an inquiry from Andrew Dessler, requesting to use it in one of his lectures. In the email, John suggested that the graphic had gained so much popularity, it would likely soon be the target of attacks from fake skeptics.

As if eavesdropping on our conversation, the first such attack on the escalator came the very next day, on 01 February 2012. The graphic had been publshed nearly 3 months earlier, and John predicted the fake skeptic response within a day's margin.

The Escalator was recently used by a number of sources in response to the denialist plea for climate inaction published in the Wall Street Journal, including Media Matters, Climate Crocks, Huffington Post, and Phil Plait at Discover Magazine's Bad Astronomy. Statistician William Briggs took issue with Phil Plait's use of the graphic. Specifically, he criticized the lack of error bars on the data used in The Escalator, making some rather wild claims about the uncertainty in the data.

"...the models that gave these dots tried to predict what the global temperature was. When we do see error bars, researchers often make the mistake of showing us the uncertainty of the model parameters, about which we do not care, we cannot see, and are not verifiable. Since the models were supposed to predict temperature, show us the error of the predictions.

I’ve done this (on different but similar data) and I find that the parameter uncertainty is plus or minus a tenth of degree or less. But the prediction uncertainty is (in data like this) anywhere from 0.1 to 0.5 degrees, plus or minus."

As tamino has pointed out, calculating an area-weighted average global temperature can hardly be considered a "prediction" and as he and Greg Laden both pointed out, BEST has provided the uncertainty range for their data, and it is quite small (see it graphically here and here). Plait has also responded to Briggs here.

The Escalating Global Warming Trend

Briggs takes his uncertainty inflation to the extreme, claiming that we can't even be certain the planet has warmed over the past 70 years.

"I don’t know what the prediction uncertainty is for Plait’s picture. Neither does he. I’d be willing to bet it’s large enough so that we can’t tell with certainty greater than 90% whether temperatures in the 1940s were cooler than in the 2000s."

It's difficult to ascertain what Briggs is talking about here. We're not using the current trend to predict (hindcast) the global temperature in 1940. We have temperature station measurements in 1940 to estimate the 1940 temperature, and data since then to estimate the warming trend. Once again, we're producing estimates, not predictions here.

Moreover, the further back in time we go and the more data we use, the smaller the uncertainty in the trend. For example, see this post by tamino, which shows that the global warming trend since 1975 is roughly 0.17 +/- 0.04°C per decade in data from NASA GISS (Figure 2). The shorter the timeframe, the larger the uncertainty in the trend. This is why it's unwise to focus on short timeframes, as the fake skeptics do in their "global warming stopped in [date]" assertions. As tamino's post linked above shows, when we limit ourselves to a decade's worth of data, the uncertainty in the trend grows to nearly +/- 0.2°C per decade (Figure 2).

Figure 2: The estimated global temperature trends through July 2011 (black dots-and-lines), upper and lower limits of the 95% confidence interval (black dashed lines), and the estimated trend since 1975 (red dashed line) using GISS land and ocean temperature data (created by tamino)

Foster and Rahmstorf (2011) also showed that when the influences of solar and volcanic activity and the El Niño Southern Oscillation are removed from the temperature data, the warming trend in the NCDC data shown in the updated Escalator is 0.175 +/- 0.012°C per decade. Quite simply, contrary to Briggs' claims, the warming trend is much larger than the uncertainty in the data. In fact, when applying the Foster and Rahmstorf methodology, the global warming trend in each of the major data sets is statistically significant since 2000, let alone 1940.

Ultimately Briggs completely misses the point of The Escalator.

"...just as the WSJ‘s scientists claim, we can’t say with any certainty that the temperatures have been increasing this past decade."

This is a strawman argument. The claim was not that we can say with certainty that surface temperatures have increased over the past decade (although global heat content has). The point is that focusing on temperatures over the past decade (as the fake skeptics constantly do) is pointless to begin with, and that we should be examining longer, statistically significant trends.

Briggs' post was of course hailed by the usual climate denial enablers (i.e. here and here), despite the rather obvious inflation of the data uncertainty, and utter lack of support for that inflation. Despite the fake skeptic struggles to go the wrong way down, The Escalator unfortunately continues ever-upward.

Check With Climate Scientists for Views on Climate

Thu, 2 Feb 2012 13:04:44 EST

In response to the latest denialist plea for climate inaction published in the Wall Street Journal (WSJ), the WSJ has published a response letter from a number of actual climate scientists, which is re-printed below.

Do you consult your dentist about your heart condition? In science, as in any area, reputations are based on knowledge and expertise in a field and on published, peer-reviewed work. If you need surgery, you want a highly experienced expert in the field who has done a large number of the proposed operations.

You published "No Need to Panic About Global Warming" (op-ed, Jan. 27) on climate change by the climate-science equivalent of dentists practicing cardiology. While accomplished in their own fields, most of these authors have no expertise in climate science. The few authors who have such expertise are known to have extreme views that are out of step with nearly every other climate expert. This happens in nearly every field of science. For example, there is a retrovirus expert who does not accept that HIV causes AIDS. And it is instructive to recall that a few scientists continued to state that smoking did not cause cancer, long after that was settled science.

Climate experts know that the long-term warming trend has not abated in the past decade. In fact, it was the warmest decade on record. Observations show unequivocally that our planet is getting hotter. And computer models have recently shown that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean. Such periods are a relatively common climate phenomenon, are consistent with our physical understanding of how the climate system works, and certainly do not invalidate our understanding of human-induced warming or the models used to simulate that warming.

Thus, climate experts also know what one of us, Kevin Trenberth, actually meant by the out-of-context, misrepresented quote used in the op-ed. Mr. Trenberth was lamenting the inadequacy of observing systems to fully monitor warming trends in the deep ocean and other aspects of the short-term variations that always occur, together with the long-term human-induced warming trend.

The National Academy of Sciences of the U.S. (set up by President Abraham Lincoln to advise on scientific issues), as well as major national academies of science around the world and every other authoritative body of scientists active in climate research have stated that the science is clear: The world is heating up and humans are primarily responsible. Impacts are already apparent and will increase. Reducing future impacts will require significant reductions in emissions of heat-trapping gases.

Research shows that more than 97% of scientists actively publishing in the field agree that climate change is real and human caused. It would be an act of recklessness for any political leader to disregard the weight of evidence and ignore the enormous risks that climate change clearly poses. In addition, there is very clear evidence that investing in the transition to a low-carbon economy will not only allow the world to avoid the worst risks of climate change, but could also drive decades of economic growth. Just what the doctor ordered.

Kevin Trenberth, Sc.D.

Distinguished Senior Scientist

Climate Analysis Section National Center for Atmospheric Research

La Jolla, Calif.

Kevin Trenberth, Sc.D, Distinguished Senior Scientist, Climate Analysis Section, National Center for Atmospheric Research

Richard Somerville, Ph.D., Distinguished Professor, Scripps Institution of Oceanography, University of California, San Diego

Katharine Hayhoe, Ph.D., Director, Climate Science Center, Texas Tech University

Rasmus Benestad, Ph.D., Senior Scientist, The Norwegian Meteorological Institute

Gerald Meehl, Ph.D., Senior Scientist, Climate and Global Dynamics Division, National Center for Atmospheric Research

Michael Oppenheimer, Ph.D., Professor of Geosciences; Director, Program in Science, Technology and Environmental Policy, Princeton University

Peter Gleick, Ph.D., co-founder and president, Pacific Institute for Studies in Development, Environment, and Security

Michael C. MacCracken, Ph.D., Chief Scientist, Climate Institute, Washington

Michael Mann, Ph.D., Director, Earth System Science Center, Pennsylvania State University

Steven Running, Ph.D., Professor, Director, Numerical Terradynamic Simulation Group, University of Montana

Robert Corell, Ph.D., Chair, Arctic Climate Impact Assessment; Principal, Global Environment Technology Foundation

Dennis Ojima, Ph.D., Professor, Senior Research Scientist, and Head of the Dept. of Interior's Climate Science Center at Colorado State University

Josh Willis, Ph.D., Climate Scientist, NASA's Jet Propulsion Laboratory

Matthew England, Ph.D., Professor, Joint Director of the Climate Change Research Centre, University of New South Wales, Australia

Ken Caldeira, Ph.D., Atmospheric Scientist, Dept. of Global Ecology, Carnegie Institution

Warren Washington, Ph.D., Senior Scientist, National Center for Atmospheric Research

Terry L. Root, Ph.D., Senior Fellow, Woods Institute for the Environment, Stanford University

David Karoly, Ph.D., ARC Federation Fellow and Professor, University of Melbourne, Australia

Jeffrey Kiehl, Ph.D., Senior Scientist, Climate and Global Dynamics Division, National Center for Atmospheric Research

Donald Wuebbles, Ph.D., Professor of Atmospheric Sciences, University of Illinois

Camille Parmesan, Ph.D., Professor of Biology, University of Texas; Professor of Global Change Biology, Marine Institute, University of Plymouth, UK

Simon Donner, Ph.D., Assistant Professor, Department of Geography, University of British Columbia, Canada

Barrett N. Rock, Ph.D., Professor, Complex Systems Research Center and Department of Natural Resources, University of New Hampshire

David Griggs, Ph.D., Professor and Director, Monash Sustainability Institute, Monash University, Australia

Roger N. Jones, Ph.D., Professor, Professorial Research Fellow, Centre for Strategic Economic Studies, Victoria University, Australia

William L. Chameides, Ph.D., Dean and Professor, School of the Environment, Duke University

Gary Yohe, Ph.D., Professor, Economics and Environmental Studies, Wesleyan University, CT

Robert Watson, Ph.D., Chief Scientific Advisor to the UK Department of Environment, Food and Rural Affairs; Chair of Environmental Sciences, University of East Anglia

Steven Sherwood, Ph.D., Director, Climate Change Research Centre, University of New South Wales, Sydney, Australia

Chris Rapley, Ph.D., Professor of Climate Science, University College London, UK

Joan Kleypas, Ph.D., Scientist, Climate and Global Dynamics Division, National Center for Atmospheric Research

James J. McCarthy, Ph.D., Professor of Biological Oceanography, Harvard University

Stefan Rahmstorf, Ph.D., Professor of Physics of the Oceans, Potsdam University, Germany

Julia Cole, Ph.D., Professor, Geosciences and Atmospheric Sciences, University of Arizona

William H. Schlesinger, Ph.D., President, Cary Institute of Ecosystem Studies

Jonathan Overpeck, Ph.D., Professor of Geosciences and Atmospheric Sciences, University of Arizona

Eric Rignot, Ph.D., Senior Research Scientist, NASA's Jet Propulsion Laboratory; Professor of Earth System Science, University of California, Irvine

Wolfgang Cramer, Professor of Global Ecology, Mediterranean Institute for Biodiversity and Ecology, CNRS, Aix-en-Provence, France

Volcanic Influence on the Little Ice Age

Wed, 8 Feb 2012 01:33:40 EST

The causes and even start and duration of the Little Ice Age (LIA), a global cooling event of approximately 0.5°C over several centuries ending in the late 19th Century, has been a challenge for climate scientists to pin down, with many possible contributing factors. A very interesting new paper by Miller et al. (2012) seeks to answer these questions by simulating the climate response to a number of large volcanic eruptions during the LIA timeframe. As the authors note, the challenge lies not only in determining the cause of the LIA, but when the event even started:

"...the natural radiative forcings are either weak or, in the case of explosive volcanism, shortlived [Robock, 2000], thus requiring substantial internal feedback. The LIA is particularly enigmatic. Despite extensive historical documentation and a wide array of proxy records that define climate change during the past millennium [Mann et al., 2008], there is no clear consensus on the timing, duration, or controlling mechanisms of the LIA."

A similar paper, Anderson et al. (2008), was previously discussed here.

The Data

Miller et al. used precisely-dated records of ice-cap growth from Arctic Canada and Iceland in their attempt to assess the timing and duration of the LIA. The ice caps exhibit little or now flow, and thus preserve rooted tundra vegetation that was alive at the time of ice-cap expansion. This enabled the scientists to use carbon dating on the vegetation. This process accurately dates the time when snowline dropped below the vegetation altitude, killing the plants, and remained on average below that site until the summer warmth of recent decades. The locations from which Miller et al. gathered vegetation samples are illustrated in Figure 1.

Figure 1: Arctic Canada sites with recently exposed entombed plants dated younger than 800 AD (circles) and older than 800 AD (triangles); Hvítárvatn, Iceland (square); Greenland temperature borehole site and sea ice record on the North Iceland shelf (round).

LIA Begins

The Miller et al. probability distribution function (PDF) and large number of vegetation klll dates toward the end of the 13th Century suggest that the LIA may have been triggered at this time, which is generally earlier than the LIA was previously thought to have begun.

"Discrete peaks in the composite PDF define widespread abrupt summer cooling events that resulted in a persistent snowline depression, allowing the expansion of ice caps over sites that did not subsequently become ice-free until the most recent decade. The cluster of kill-dates between 1275 and 1300 AD, following 300 years with few kill dates, defines an abrupt summer temperature decrease in the late 13th Century."

Figure 2, particularly frames b and c, illustrate the ice-cap growth at the end of the 13th Century, coinciding with an increase in atmospheric aerosols due to a period of high volcanic activity caused by four closely-spaced volcanic eruptions.

"The PDF [probability distribution function] peak defining abrupt LIA cooling 1275–1300 AD coincides with an interval of four large stratospheric sulfur loadings from explosive volcanism following a multi-centennial warm interval, during which complete revegetation of deglaciated sites would have fully reset the radiocarbon clock (Figure 2c)."

Figure 2: (a) Total solar irradiance (VSK [Schmidt et al., 2011]). (b) Global stratospheric sulfate aerosol loadings [Gao et al., 2008]. (c) Ice cap expansion dates based on a composite of 94 Arctic Canada calibrated 14C PDFs. (d) 30-year running mean varve thickness in Hvítárvatn sediment core HVT03-2 [Larsen et al., 2011]. (e) Arctic Ocean sea ice recorded in a sediment core on the north Iceland shelf [Massé et al., 2008]; heavy sea ice years correlate with anomalously cold summers across Iceland. (f) Temperature anomalies over southern Greenland (wrt 1881–1980 AD mean) from the borehole temperature inversion at DYE-3 [Dahl-Jensen et al., 1998].

The peaks shown in Figure 2c define widespread abrupt summer cooling events that resulted in a persistent snowline depression, allowing the expansion of ice caps over sites that did not subsequently become ice-free until recent years.

Feedbacks

A difficulty in attributing the LIA cooling to volcanic eruptions is that aerosols have a short residence time in the atmosphere, generally being washed out after just a year or two. If spaced relatively close together, volcanic eruptions can have a cooling effect over the span of a few decades, but the LIA was a much longer event.

"Decadally paced eruptions may produce greater cooling than a single large eruption if the recurrence interval is shorter than the upper ocean temperature relaxation time of decades [Schneider et al., 2009]. This may explain multidecadal cold episodes, but many Canadian sites that became ice-covered ~1275 AD and ~1450 AD, following episodes of strong explosive volcanism, remained continuously ice-covered until the most recent decade (Figure 2c)."

Thus in order to explain a long-term cooling like the LIA, the volcanic eruptions must trigger certain feedback effects in order to extend their impact on the climate. Miller et al. ran transient climate model simulations and believe they have identified some of these possible feedbacks.

First, the reduced incoming solar radiation due to the volcanic aerosols blocking sunlight allowed Arctic ice to expand. The Arctic ice expansion increases the overall reflectivity (albedo) of the Earth, causing it to cool further. The increase in Arctic sea ice in the north Atlantic Ocean also bring more cold and fresh water to the region, impacting the ocean circulation.

"...increased southward sea ice export following the eruptions led to freshening and vertical stratification of the North Atlantic subpolar gyre, reducing open ocean convection and thus weakening the Atlantic meridional overturning circulation."

Miller et al. concluded that these feedbacks were sufficient to sustain a LIA cooling for centuries. Their theory is supported by reconstructions of sea ice around Iceland, where sea ice does not form, and only appears when there is a large export of sea ice from the Arctic Ocean.

"Sea ice was rarely present on the North Iceland shelf from 800 AD until the late 13th Century, when an abrupt rise in sea-ice proxies suggests a rapid increase in Arctic Ocean sea ice export, followed by another increase ~1450 AD, after which sea ice was continuously present until the 20th Century [Massé et al., 2008] (Figures 1 and 2e). The increase in sea ice north of Iceland at the start of the LIA, and its persistence throughout the LIA, supports our modeling experiments suggesting explosive volcanism and associated feedbacks resulted in a self-sustaining expanded sea-ice state beginning 1275–1300 AD."

Summary

Miller et al. suggest that a period of anomalously high volcanic activity at the end of the 13th Century could have triggered Arctic sea ice and ocean circulation feedbacks sufficient to cause the centuries-long cooling associated with the LIA. The authors conclude by noting that while the decline in solar activity associated with the Maunder Minimum in the 17th Century contributed to the LIA cooling, a decline in solar irradiance is not necessary to explain the initial triggering of the LIA cooling.

"The coincidence of repeated explosive volcanism with centuries of lower-than-modern solar irradiance (Figure 2a) [Schmidt et al., 2011] indicates that volcanic impacts were likely reinforced by external forcing [Mann et al., 2009], but that an explanation of the LIA does not require a solar trigger."

However, it's also worth noting that it took four closely-spaced large volcanic eruptions to trigger these feedbacks and LIA cooling. In most cases, the effects of volcanic eruptions on the global temperature are limited to a timespan of a few years.

Additionally, while the data supporting the volcanic trigger of the LIA in the paper are fairly convincing, the modeling suggesting that the associated feedbacks are sufficient to sustain cold temperatures for several centuries is less conclusive. In another paper, Zhang et al. (2011), only two simulations out of four show the proposed feedback. In an interview with Science magainze regarding this paper, NASA climate scientist Gavin Schmidt agreed that too few model runs have been performed to conclusively demonstrate that the cooling feedbacks sustained the LIA by themselves.

"I think it is likely that the abrupt start to the Little Ice Age in the late 13th century is volcanic in origin...I'm far less convinced that this is the cause of the subsequent centuries of climate change."

New research from last week 5/2012

Tue, 7 Feb 2012 21:57:59 EST

Scientists are telling about whats and whys:

Ozone has weekly lows and highs.
Range shifts up north for butterflies.
Cloud height tells us about falling skies.
Open up Bering strait and the seesaw dies.
Earthquakes cool groundwater unless it's lies.
In the age of dinosaurs there were not much ice,
but it was volcanism that started the age of little ice.
Knowledge of pressure driven tsunamis makes us wise.
Northern hemisphere is warming at a rate that is surprise.
Does the India's DTR increase disturb the production of rice?
For climate permafrost carbon feedback is another warming slice.

Yet another weekly paper batch, oh, isn't that nice...

Permafrost carbon feedback amplifies global warming

Estimating the near-surface permafrost-carbon feedback on global warming - von Deimling et al. (2012) [FULL TEXT]

Abstract: "Thawing of permafrost and the associated release of carbon constitutes a positive feedback in the climate system, elevating the effect of anthropogenic GHG emissions on global-mean temperatures. Multiple factors have hindered the quantification of this feedback, which was not included in climate carbon-cycle models which participated in recent model intercomparisons (such as the Coupled Carbon Cycle Climate Model Intercomparison Project – C⁴MIP) . There are considerable uncertainties in the rate and extent of permafrost thaw, the hydrological and vegetation response to permafrost thaw, the decomposition timescales of freshly thawed organic material, the proportion of soil carbon that might be emitted as carbon dioxide via aerobic decomposition or as methane via anaerobic decomposition, and in the magnitude of the high latitude amplification of global warming that will drive permafrost degradation. Additionally, there are extensive and poorly characterized regional heterogeneities in soil properties, carbon content, and hydrology. Here, we couple a new permafrost module to a reduced complexity carbon-cycle climate model, which allows us to perform a large ensemble of simulations. The ensemble is designed to span the uncertainties listed above and thereby the results provide an estimate of the potential strength of the feedback from newly thawed permafrost carbon. For the high CO₂ concentration scenario (RCP8.5), 33–114 GtC (giga tons of Carbon) are released by 2100 (68 % uncertainty range). This leads to an additional warming of 0.04–0.23 °C. Though projected 21st century permafrost carbon emissions are relatively modest, ongoing permafrost thaw and slow but steady soil carbon decomposition means that, by 2300, about half of the potentially vulnerable permafrost carbon stock in the upper 3 m of soil layer (600–1000 GtC) could be released as CO₂, with an extra 1–4 % being released as methane. Our results also suggest that mitigation action in line with the lower scenario RCP3-PD could contain Arctic temperature increase sufficiently that thawing of the permafrost area is limited to 9–23 % and the permafrost-carbon induced temperature increase does not exceed 0.04–0.16 °C by 2300."

Citation: Schneider von Deimling, T., Meinshausen, M., Levermann, A., Huber, V., Frieler, K., Lawrence, D. M., and Brovkin, V.: Estimating the near-surface permafrost-carbon feedback on global warming, Biogeosciences, 9, 649-665, doi:10.5194/bg-9-649-2012, 2012.

New NH temperature reconstruction shows current rate of warming largest in last 1200 years

Northern Hemisphere temperature patterns in the last 12 centuries - Ljungqvist et al. (2012) [FULL TEXT]

Abstract: "We analyse the spatio-temporal patterns of temperature variability over Northern Hemisphere land areas, on centennial time-scales, for the last 12 centuries using an unprecedentedly large network of temperature-sensitive proxy records. Geographically widespread positive temperature anomalies are observed from the 9th to 11th centuries, similar in extent and magnitude to the 20th century mean. A dominance of widespread negative anomalies is observed from the 16th to 18th centuries. Though we find the amplitude and spatial extent of the 20th century warming is within the range of natural variability over the last 12 centuries, we also find that the rate of warming from the 19th to the 20th century is unprecedented in the context of the last 1200 yr. The positive Northern Hemisphere temperature change from the 19th to the 20th century is clearly the largest between any two consecutive centuries in the past 12 centuries. These results remain robust even after removing a significant number of proxies in various tests of robustness showing that the choice of proxies has no particular influence on the overall conclusions of this study."

Citation: Ljungqvist, F. C., Krusic, P. J., Brattström, G., and Sundqvist, H. S.: Northern Hemisphere temperature patterns in the last 12 centuries, Clim. Past, 8, 227-249, doi:10.5194/cp-8-227-2012, 2012.

Less population variability in butterfly range-edge due to poleward range shifts

Reduced variability in range-edge butterfly populations over three decades of climate warming - Oliver et al. (2012)

Abstract: "Populations at the high latitude edge of species’ geographic ranges are thought to show larger interannual population fluctuations, with subsequent higher local extinction risk, than those within the ‘core’ climatic range. As climate envelopes shift northwards under climate warming, however, we would expect populations to show dampened variability. We test this hypothesis using annual abundance indices from 19 butterfly species across 79 British monitoring sites between 1976 and 2009, a period of climatic warming. We found that populations in the latter (warmer) half of the recording period show reduced interannual population variability. Species with more southerly European distributions showed the greatest dampening in population variability over time. Our results suggest that increases in population variability occur towards climatic range boundaries. British sites, previously existing at the margins of suitable climate space, now appear to fall closer to the core climatic range for many butterfly species."

Citation: Tom H. Oliver, David B. Roy, Tom Brereton, Jeremy A. Thomas, Global Change Biology, DOI: 10.1111/j.1365-2486.2012.02659.x.

Pacific-Atlantic seesaw seems to work only when Bering strait is closed

The Pacific-Atlantic seesaw and the Bering Strait - Hu et al. (2012)

Abstract: "Paleo proxy data and previous modeling studies both indicate that the massive discharge of icebergs into the North Atlantic may have led to a (nearly) collapsed Atlantic meridional overturning circulation (AMOC), resulting in a seesaw-like climate change between the North Pacific and North Atlantic, with a warming in the former and a cooling in the latter. Here by using a fully coupled climate model, we show that this Pacific-Atlantic seesaw associated with changes of the AMOC can only occur when the Bering Strait is closed. As this strait is closed, the oceanic communication between the North Pacific and Atlantic is cut off. When AMOC collapses, the North Atlantic becomes cooler, but the North Pacific becomes warmer due to the buildup of the Pacific meridional overturning circulation which transports more warm and salty subtropical water into the North Pacific, leading to seesaw-like climate changes in the two ocean basins."

Citation: Hu, A., G. A. Meehl, W. Han, A. Abe-Ouchi, C. Morrill, Y. Okazaki, and M. O. Chikamoto (2012), The Pacific-Atlantic seesaw and the Bering Strait, Geophys. Res. Lett., 39, L03702, doi:10.1029/2011GL050567.

Global cloud height decreased between 2000 and 2010

Global cloud height fluctuations measured by MISR on Terra from 2000 to 2010 - Davies & Molloy (2012)

Abstract: "Self-consistent stereo measurements by the Multiangle Imaging SpectroRadiometer (MISR) on the Terra satellite yield a decrease in global effective cloud height over the decade from March 2000 to February 2010. The linear trend is −44 ± 22 m/decade and the interannual annual difference is −31 ± 11 m between the first and last years of the decade. The annual mean height is measured with a sampling error of 8 m, which is less than the observed interannual fluctuation in global cloud height for most years. A maximum departure from the 10-year mean, of −80 ± 8 m, is observed towards the end of 2007. These height anomalies correlate well with the changes in the Southern Oscillation Index, with the effective height increasing over Indonesia and decreasing over the Central Pacific during the La Niña phase of the oscillation. After examining the net influence of Central Pacific/Indonesia heights on the global mean anomaly, we conclude that the integrated effects from outside these regions dominate the global mean height anomalies, confirming the existence of significant teleconnections."

Citation: Davies, R. and M. Molloy (2012), Global cloud height fluctuations measured by MISR on Terra from 2000 to 2010, Geophys. Res. Lett., 39, L03701, doi:10.1029/2011GL050506.

Not much polar ice during Jurassic and Cretaceous periods

Warm Middle Jurassic–Early Cretaceous high-latitude sea-surface temperatures from the Southern Ocean - Jenkyns et al. (2012) [FULL TEXT]

Abstract: "Although a division of the Phanerozoic climatic modes of the Earth into "greenhouse" and "icehouse" phases is widely accepted, whether or not polar ice developed during the relatively warm Jurassic and Cretaceous Periods is still under debate. In particular, there is a range of isotopic and biotic evidence that favours the concept of discrete "cold snaps", marked particularly by migration of certain biota towards lower latitudes. Extension of the use of the palaeotemperature proxy TEX₈₆ back to the Middle Jurassic indicates that relatively warm sea-surface conditions (26–30 °C) existed from this interval (∼160 Ma) to the Early Cretaceous (∼115 Ma) in the Southern Ocean, with a general warming trend through the Late Jurassic followed by a general cooling trend through the Early Cretaceous. The lowest sea-surface temperatures are recorded from around the Callovian–Oxfordian boundary, an interval identified in Europe as relatively cool, but do not fall below 25 °C. The early Aptian Oceanic Anoxic Event, identified on the basis of published biostratigraphy, total organic carbon and carbon-isotope stratigraphy, records an interval with the lowest, albeit fluctuating Early Cretaceous palaeotemperatures (∼26 °C), recalling similar phenomena recorded from Europe and the tropical Pacific Ocean. Extant belemnite δ¹⁸O data, assuming an isotopic composition of waters inhabited by these fossils of −1‰ SMOW, give palaeotemperatures throughout the Upper Jurassic–Lower Cretaceous interval that are consistently lower by ∼14 °C than does TEX₈₆ and the molluscs likely record conditions below the thermocline. The long-term, warm climatic conditions indicated by the TEX₈₆ data would only be compatible with the existence of continental ice if appreciable areas of high altitude existed on Antarctica, and/or in other polar regions, during the Mesozoic Era."

Citation: Jenkyns, H. C., Schouten-Huibers, L., Schouten, S., and Sinninghe Damsté, J. S.: Warm Middle Jurassic–Early Cretaceous high-latitude sea-surface temperatures from the Southern Ocean, Clim. Past, 8, 215-226, doi:10.5194/cp-8-215-2012, 2012.

Earthquakes decrease groundwater temperature

Transient change in groundwater temperature after earthquakes - Wang et al. (2012)

Abstract: "Postseismic decrease in groundwater temperature was documented on the upper rim of a large alluvial fan near the epicenter of the 1999 M_w 7.5 Chi-Chi earthquake (Taiwan). We use a model of coupled heat transport and groundwater flow, constrained by documented water-level changes, to interpret this change. We show that groundwater temperature is sensitive to earthquake-induced flow and the observed temperature decrease may be explained by increased groundwater discharge due to earthquake-enhanced vertical permeability. The result implies that heat flow near active mountain fronts may be lowered by recurrent earthquakes."

Citation: Chi-yuen Wang, Michael Manga, Chung-Ho Wang and Chieh-Hung Chen, Geology, v. 40 no. 2 p. 119-122, doi: 10.1130/G32565.1.

Meteorological tsunamis driven by atmospheric pressure disturbances

Northern Adriatic meteorological tsunamis: Observations, link to the atmosphere, and predictability - Šepić et al. (2012)

Abstract: "A total of 16 events of tsunami-like sea level oscillations are documented in the northern Adriatic between 1955 and 2010. These oscillations, recorded at the long-term operating Rovinj tide gauge, are characterized by wave heights of up to 60 cm, periods of 20 to 150 min, and duration of 1 to 48 h. The sea level oscillations are found to be coincident with pronounced atmospheric pressure disturbances characterized by a 2–4 hPa air pressure change over 10 min. Convective activity is recognized as the most likely source of atmospheric pressure disturbances. Analysis of propagation speed and direction of the atmospheric pressure disturbances indicates that the sea level oscillations were generated and enhanced via the Proudman resonance over a wide and shallow northern Adriatic shelf. Typical conditions under which pronounced air pressure disturbances occur include an air pressure surface minimum centered over the northern Adriatic, a temperature front at a height of approximately 850 hPa, and a strong southwesterly jet stream with wind speeds reaching 20–30 m/s at a height of approximately 500 hPa over the northern Adriatic. Based on these parameters, a possibility for forecasting tsunami-like sea level oscillations from synoptic conditions is discussed. It appears that under favorable synoptic conditions sea level oscillations are more likely to occur than to not. However, no reliable conclusion on strength of an event can be reached from synoptic conditions only."

Citation: Šepić, J., I. Vilibić, and N. Strelec Mahović (2012), Northern Adriatic meteorological tsunamis: Observations, link to the atmosphere, and predictability, J. Geophys. Res., 117, C02002, doi:10.1029/2011JC007608.

Searching for causes of ozone weekend effect in California

Airborne and ground-based observations of a weekend effect in ozone, precursors, and oxidation products in the California South Coast Air Basin - Pollack et al. (2012)

Abstract: "Airborne and ground-based measurements during the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May/June 2010 show a weekend effect in ozone in the South Coast Air Basin (SoCAB) consistent with previous observations. The well-known and much-studied weekend ozone effect has been attributed to weekend reductions in nitrogen oxide (NO_x = NO + NO₂) emissions, which affect ozone levels via two processes: (1) reduced ozone loss by titration and (2) enhanced photochemical production of ozone due to an increased ratio of non-methane volatile organic compounds (VOCs) to NO_x. In accord with previous assessments, the 2010 airborne and ground-based data show an average decrease in NO_x of 46 ± 11% and 34 ± 4%, respectively, and an average increase in VOC/NO_x ratio of 48 ± 8% and 43 ± 22%, respectively, on weekends. This work extends current understanding of the weekend ozone effect in the SoCAB by identifying its major causes and quantifying their relative importance from the available CalNex data. Increased weekend production of a VOC-NO_x oxidation product, peroxyacetyl nitrate, compared to a radical termination product, nitric acid, indicates a significant contribution from increased photochemical production on weekends. Weekday-to-weekend differences in the products of NO_x oxidation show 45 ± 13% and 42 ± 12% more extensive photochemical processing and, when compared with odd oxygen (O_x = O₃ + NO₂), 51 ± 14% and 22 ± 17% greater ozone production efficiency on weekends in the airborne and ground-based data, respectively, indicating that both contribute to higher weekend ozone levels in the SoCAB."

Citation: Pollack, I. B., et al. (2012), Airborne and ground-based observations of a weekend effect in ozone, precursors, and oxidation products in the California South Coast Air Basin, J. Geophys. Res., 117, D00V05, doi:10.1029/2011JD016772.

Volcanism drove Northern Hemisphere to Little Ice Age

Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks - Miller et al. (2012)

Abstract: "Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century-scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required."

Citation: Miller, G. H., et al. (2012), Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophys. Res. Lett., 39, L02708, doi:10.1029/2011GL050168.

Diurnal temperature range has increased in India

Variations in diurnal temperature range over India: Under global warming scenario - Rai et al. (2012)

Abstract: "Annual, seasonal, and monthly trends in surface air temperature were examined over India during the period 1901–2003. Besides this, annual and seasonal trends were also scrutinized in view of global warming concerns during the 2 non-global (1901–1909 and 1946–1975) and global (1910–1945 and 1976–2003) warming periods as defined by Intergovernmental Panel on Climate Change. A significant increasing trend of 0.743, 0.224, 0.484, and 0.52°C (100 yr)⁻¹ has been observed in maximum (T_max), minimum (T_min), mean (T_mean) temperatures, and diurnal temperature range (DTR; T_max − T_min), respectively during the period 1901–2003. The annual temperatures (T_mean, T_min, and T_max) show a cooling (warming) tendency during the non-global (global) warming periods, apart from the second non-global warming period of T_max. The seasonal trends in T_min and T_mean also show similar behavior; whereas, T_max shows warming in all sub-periods, excluding the first non-global warming period of the pre-monsoon and monsoon. Seasonal analysis depicts that, both post-monsoon and winter seasons are getting warmer with regard to T_max and T_min. During the analysis as well as in non-global and global warming periods, annual DTR has increased. DTR increases in all seasons, with the largest increase in winter and the smallest in post-monsoon; whereas monthly analysis reveals that all the months, except March, October, and November are contributing significantly to the annual increase of DTR. The partial correlation analysis reveals that the total cloud cover along with the secondary factors like precipitation and soil-moisture are responsible for increase in DTR over India during the period 1948–2003."

Citation: Rai, A., M. K. Joshi, and A. C. Pandey (2012), Variations in diurnal temperature range over India: Under global warming scenario, J. Geophys. Res., 117, D02114, doi:10.1029/2011JD016697.

CLASSIC OF THE WEEK: Callendar (1938)

The artificial production of carbon dioxide and its influence on temperature - Callendar (1938) [FULL TEXT]

Abstract: "By fuel combustion man has added about 150,000 million tons of carbon dioxide to the air during the past half century. The author estimates from the best available data that approximately three quarters of this has remained in the atmosphere. The radiation absorption coefficients of carbon dioxide and water vapour are used to show the effect of carbon dioxide on “sky radiation.” From this the increase in mean temperature, due to the artificial production of carbon dioxide, is estimated to be at the rate of 0.003°C. per year at the present time. The temperature observations at 200 meteorological stations are used to show that world temperatures have actually increased at an average rate of 0.005°C. per year during the past half century."

Citation: G. S. Callendar, Quarterly Journal of the Royal Meteorological Society, Volume 64, Issue 275, pages 223–240, April 1938, DOI: 10.1002/qj.49706427503.

This is a cross-post from AGW Observer. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. At least some of these are also retweeted in Skeptical Science Twitter page. Here's the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

Cool climate papers 2011

Sat, 4 Feb 2012 19:28:20 EST

The Skeptical Science audience largely were not monitoring my new research of last week feature during last year (this is painfully obvious from the visitor counts of my blog), so I think a glimpse of that might be in order. One of the points highlighting some selected papers of last week is to show that climate science is cool. Therefore I decided to make a selection of cool climate papers of last year. While I'm browsing through new climate related science and looking at certain research paper, I frequently think that this is cool. Below you can see some of the studies from last year I thought were cool. There is one paper for each week and I have subjectively decided which is the coolest paper of that week. I won't listen to complaints but you are welcome to show your own selections.

I should note that in some occasions these studies show results that are not very nice, so I'm not suggesting that those results are cool, but that the science of the study is cool. Sometimes I had to leave out some very cool studies because there were some other study in the same week I wanted to include. I would also like to note that generally all science is cool but these are kind of papers that highlight it.

Week 1: Jezek et al. used radar measurements to study Jakobshavn Glacier sliding in Greenland.

Week 2: Bar-Or et al. note that it is actually quite difficult to find cloud-free pixels from MODIS data.

Week 3: Pongratz et al. show that historic wars and epidemics did not have strong enough effect to Earth's carbon cycle so that they would be detected in ice core carbon dioxide records.

Week 4: Bernier et al. estimated the climate impact of black spruce forest turning to lichen-spruce woodlands in North-America.

Week 5: Kucharski et al. model simulations suggest that Atlantic warming causes eastern tropical Pacific to cool.

Week 6: Turtle et al. have observed that even if Titan, the moon of Saturn, has very weird weather system, it seems to have seasonal changes, which seem to occur in the tropospheric methane clouds.

Week 7: Yamano et al. found that Japan temperate area corals are expanding polewards at high speed - 14 km per year.

Week 8: Roquet et al. have equipped elephant seals with data loggers to measure ocean temperature and salinity.

Week 9: Therrell & Trotter analysed the weather and climate information in native american pictographic winter calendars.

Week 10: Schweger et al. studied why Holocene forests differ from those of previous interglacials and suggest that one important factor that wasn't present in previous interglacials is mankind burning stuff.

Week 11: D’Arrigo et al. studied NAO and ENSO reconstructions back in time and suggested that the anomalously cold winter 1783-1784 was not caused by the erution of volcano Laki, but that it was caused by similar combination of NAO-ENSO phases that made winter 2009-2010 so severe in some places of Northern Hemisphere. By the way, a recent study showed that eruption plume of Laki probably didn't reach stratosphere and therefore probably didn't cause the cold winter 1783-1784.

Week 12: Bokhorst et al. used infrared heating lamps and soil warming cables to simulate week-long extreme winter warming events in sub-arctic heathland to find out that winter warming events cause considerable plant damage by melting insulating snow.

Week 13: Kosintsev et al. used intestinal contents of a baby mammoth to reconstruct the environment where this mammoth called Lyuba lived over 40000 years ago.

Week 14: Webb et al. noted that grapes in Australian vineyards are attaining maturity earlier than before, so this must be one of the positive sides of global warming.

Week 15: Ding et al. suggest based on observational data that West Antarctic warming actually originates from central tropical Pacific.

Week 16: Caccianiga et al. studied ecosystems on the surface of glacier.

Week 17: Retallack studied fossil preservation through ages and argued that GHG-driven climate changes might help in fossil preservation. So, it seems that at least we leave lot of study material for future generations.

Week 18: Anderson reviewed the evidence on how important celebrities are in climate change communication.

Week 19: De Boeck & Verbeeck showed that while climate affects drought conditions, drought also affects climate.

Week 20: Rea et al. suggest that Earth's climate doesn't have a stationary state to which it returns after climate events.

Week 21: Roy & Peltier studied Earth's rotation parameters and suggested that global warming has affected Earth's rotation.

Week 22: Csank et al. made a tree ring based climate reconstruction that covers 250 years of Early Pliocene (4-5 millions of years ago).

Week 23: Lee & Sohn showed that dust events in Mongolia have increased and that they "appear to be caused by degraded surface vegetation and reduced soil moisture associated with intensified drought conditions".

Week 24: Mims et al. showed an alternative for those who think that water vapor measurements from those expensive satellite projects are not to be trusted - you can simply point a cheap IR thermometer to the sky and measure away.

Week 25: Kourtev et al. studied bacteria in cumulus clouds and found that: "Cloud water bacterial communities appeared to be dominated by members of the cyanobacteria, proteobacteria, actinobacteria and firmicutes".

Week 26: Park et al. note that in future warm climate there will still be cold surges and that living things that have adapted to the warmer climate will suffer from the cold surges.

Week 27: Ballenger et al. reviewed the evidence to see if Younger Dryas climate chenge affected mankind of that time and find that there are significant cultural changes that coincide with the YD event.

Week 28: Camuffo & Bertolin present earliest temperature observations in the world - the Medici network (1654-1670).

Week 29: Kurtén et al. show that when a burst of methane is emitted to the atmosphere, it is not enough to just calculate its radiative forcing, but you also need to consider the feedbacks relating to the methane chemistry in the atmosphere.

Week 30: Jeong et al. suggest that future greening in the circumpolar high-latitude regions amplifies surface warming in the growing season because there will be more absorption of sunlight.

Week 31: Pleijel & Uddling found that wheat grain yield might or might not increase with elevated carbon dioxide but there will be less protein in wheat grain at any case.

Week 32: Muto et al. made borehole firn temperature measurements in East Antarctica and found a warming trend.

Week 33: Wanner et al. studied Holocene temperature and precipitation records and found no clear cyclicity in climate events and also that the events behaved spatially differently.

Week 34: Gao et al. found many reasons why the surface area of Lake Chad has decreased by more than 90%.

Week 35: Guirguis et al. showed that in climate appearances can be deceiving. They reported that last two winters were anomalously warm in Northern Hemisphere even if the cold events in some parts gained headline space.

Week 36: Gatebe et al. used airborne radiation measurements to show that ship wakes can increase ocean reflectance by more than 100%. They also calculated that the cooling effect from increased reflectance from ship wakes globally would be about 0.14 milliwatts per square meter.

Week 37: Arrigo & van Dijken showed another example of things you can do with satellites by measuring daily changes in Arctic Ocean phytoplankton. It seems that as soon as ocean gets free of ice, phytoplankton primary production increases.

Week 38: Diamond et al. suggested that tropical ants have lower warming tolerances than temperate ants despite greater increases in temperature at higher latitudes.

Week 39: Wik et al. spent some time counting gas bubbles in an Arctic lake ice and while studying the results they decided it might not tell much about the methane flux of the lake.

Week 40: VanCuren studied how albedo modification by building cool roofs would affect climate.

Week 41: Matuszko studied the effect of clouds on solar radiation and found that the greatest amount of solar radiation can be detected on Earth's surface when sky is partly cloudy.

Week 42: Haywood et al. note that while water vapor is strong greenhouse gas, it also causes dimming to sunlight.

Week 43: Inauen et al. found that glacier forefield plants increase their root biomass and decrease their above-ground biomass when carbon dioxide concentration increases.

Week 44: Macnab & Barber study shows that fish might be in for some bad times because it seems that fish parasites grow faster in warmer water.

Week 45: Attanasio et al. use Granger causality analysis to global temperature and get clear signal from greenhouse gases while getting no signal from natural forcing.

Week 46: Fyfe et al. show that climate model predicts decadal temperature trends skillfully.

Week 47: Rautiainen et al. show that the devil is in the details and make an analysis (with spectral measurements and such) the albedo of Scots pine shoots.

Week 48: Nesje et al. have studied ancient reindeer hunting artefacts, which is cool by itself, but these particular ones were recovered when ice in southern Norway, that had covered them for hundreds of years, melted. The artefacts were then used to gain information of past climate.

Week 49: Graven & Gruber determine radiocarbon emissions from nuclear power industry and estimate how they affect atmospheric radiocarbon concentration globally.

Week 50: Svensson et al. use new methodology and reveal previously unseen annual layers from Eemian interglacial in Greenland NGRIP ice core.

Week 51: Junkermann et al. demonstrate that technologies cleaning up coal power plant emissions might come with side effects to the climate, especially regionally.

Week 52: Chen et al. have made a tree ring reconstruction of temperatures back to 1850 in southeast China. Yes, I know that this doesn't sound particularly cool but these are winter temperatures they reconstructed.

2012 SkS Weekly Digest #4

Mon, 30 Jan 2012 05:43:18 EST

SkS Highlights

John Cook's post, The National Center for Science Education defends climate science in high schools started the week off with bang, generating nearly 100 comments to date. Cook followed with the Debunking Handbook: update and feedback. Dana added to his "fact checking" posts with Patrick Michaels Continues to Distort Hansen 1988, Part 1 and Part 2.

Toon of the Week

Issue of the Week

How long have you been a reader of SkS? How did you become aware of its existence? How many times a week do you visit the site?

What issues would you like to discuss in future editions of the Weekly Digest?

The Week in Review

A complete listing of the articles posted on SkS during the past week.

David Archibald Exaggerates the Solar Influence on Future Climate Change by Dana

Bilal Bomani, Cutting Edge Biofuels from NASA by Rob Honeycutt

Katharine Hayhoe, Intent to Intimidate by Rob Honeycutt

Public talk: Global Warming - The Full Picture by John Cook

New temperature record for the Arctic in 2011 by Neven

NASA scientists expect more rapid global warming in the very near future (part 1) by Rob Painting

Patrick Michaels Continues to Distort Hansen 1988, Part 2 by Dana

New research from last week 3/2012 by Ari Jokimäki

Patrick Michaels Continues to Distort Hansen 1988, Part 1 by Dana

Debunking Handbook: update and feedback by John Cook

The National Center for Science Education defends climate science in high schools by John Cook

Coming Soon

A list of articles that are in the SkS pipeline. Most of these articles, but not necessarily all, will be posted during the week

Examining the Latest Climate Denialist Plea for Inaction (Dana)
New research from last week 4/2012 (Ari Jokimäki)
Measurements show Earth heating up, think tanks & newspapers disagree (MarkR)
Climate change policy: Oil's tipping point has passed (John H)
The Year After McLean - A Review of 2011 Global Temperatures (Dana)
Major Study of Ocean Acidification Helps Scientists Evaluate Effects of Atmospheric Carbon Dioxide on Marine Life (John Hartz)
Greenhouse Effect Basics: Warm Earth, Cold Atmosphere (Tom Curtis)
Glaciers have retreated worldwide (MarkR)
RW Wood and the Greenhouse Effect (Eli Rabbett)

SkS in the News

A Comprehensive Review of the Causes of Global Warming was re-posted by Triple Pundit.

Arctic methane outgassing on the E Siberian Shelf was re-posted by TreeHugger.

Rob Painting also guest posted NASA scientists expect more rapid global warming in the very near future (part 1) on Planetsave.

SkS Spotlights

The Climate and Carbon Science component of the US Lawrence Livermore National Laboratory (LLNL) is a fantastic resource for SkS readers to tap into.

The Climate and Carbon Science Mission:

In keeping with its mission to "enhance the energy and environmental security of the nation" LLNL promotes the many climate and carbon science research and development efforts that are described on these pages. These efforts involve teams of both environmental and computer scientists, as well as diverse support personnel, who work together to achieve scientific and technical innovations directed toward pressing national and international problems in these fields.

Click here to access the home page of the LLNL's Climate and Science initiative.

Measurements show Earth heating up, think tanks & newspapers disagree

Thu, 2 Feb 2012 01:20:22 EST

The Global Warming Policy Foundation (GWPF) is a British political think tank that attacks climate science. Its commentary is often regurgitated by journalists at newspapers with similar political opinions on climate science such as the Daily Mail, Express and Telegraph (whose consulting science editor is a GWPF adviser).

The Daily Mail recently published an article covering two bits of science news. One is that the UK Met Office and their partners are updating their global temperature data and including more measurements from Russia and around the Arctic. The data aren't publicly available yet, but graphs from a Met Office presentation suggest that 2005 and 2010 could be warmer than the previous record holder (1998), bringing the British data into agreement with NASA and the National Climatic Data Centre.

The other bit of science news is research on how the Sun is expected to cool down slightly in the coming decades. "The likely reduction in the warming by 2100 is found to be between 0.06 and 0.1K" (Jones, Lockwood & Stott, 2012), much less than the 0.17 C warming per decade measured since the 1970s (1 K is the same size as 1 degree Celsius).

Gareth Jones, the climate science expert who led the Met Office research said "this research shows that the most likely change in the Sun's output will not have a big impact on global temperatures or do much to slow the warming we expect from greenhouse gases."

The Daily Mail's interpretation is the opposite of what the scientists reported, and dutifully parrots GWPF talking points. The article claims we're possibly heading for a "mini ice age", that there has been "no warming for 15 years" and quotes the GWPF's Benny Peiser's prophecies of doom for climate models.

The data the Global Warming Policy Foundation won't want you to see

In the past 15 years the upper 700 metres of the ocean have gained the amount of heat that would be released by around 1 billion Hiroshima bombs exploding. Hundreds of billions of tons of ice have melted, and needed millions of Hiroshima bombs worth of energy to do so. The deeper oceans have also warmed up and all of these things lead to rising sea levels which satellites see clearly over the past 15 years. The GWPF and Daily Mail simply ignore this data when making their "15 years" claim.

Figure 1 - Earth's heat content based on Church et al, 2011. Graph by crossing out data ignored by the Global Warming Policy Foundation. If you work for the GWPF, do not UNDER ANY CIRCUMSTANCES look at the data outside of the circled area and if you are a journalist who supports the GWPF, do not UNDER ANY CIRCUMSTANCES let your readership know about the crossed-out data.

Figure 2 - Suggested second page of the Global Warming Policy Foundation's Guide to Global Warming. Data that disagree with the political opinions of the GWPF have been crossed out. Look at the stuff inside the black circle, DO NOT LOOK AT ANYTHING ELSE.

Their claim is based on atmospheric temperatures measured by thermometers and satellites, because over the past 15 years the warming in Earth's oceans and ice is obvious.

At Skeptical Science we've explained before why short term trends in atmospheric temperatures are not good indicators for global warming, as the atmosphere is very sensitive to natural cycles and is constantly swapping heat with ice and the oceans. This makes them a 'skeptics'' favourite for cherry picking. The Skeptical Science explanation is based on peer reviewed science done by climate scientists and statisticians (Santer et al, 2011; Foster & Rahmstorf, 2011).

You need to look at all of the data rather than ignoring (or in some cases, deleting) most of it. However, in this case it appears that even with ignoring most data because it disagrees with their opinion, it's a swing and a miss from the think tank as both satellites and thermometer measurements show warming.

Figure 3 - Annual measurements of temperature changes from NASA thermometer data, and monthly measurements from UAH satellite data along with least-squares trendlines showing warming. Starting the trend in 1998 reduces the size of the warming trend, but it is still warming. NASA data used as British data is currently being updated and latest version is not available online. Measurements of air temperature for the past 15 years were the data specially selected by the GWPF think tank and the Daily Mail's journalist to try and persuade people that global warming has stopped.

The Met Office responds and lessons for the media

The newspaper article has an air of credibility thanks to hiding its selective data-blindness and favourable interviewing of some of the small portion of climate 'skeptic' scientists. It sticks very strongly to the think tank script, the same script as is repeated by think tank mouthpieces from Australia to the US.

Published, peer reviewed science says that the Sun is likely to cool down slightly, but that the effect will cancel less than 3% of the global warming expected by 2100 on our current path. Think tanks and journalists want to tell you that global warming isn't a problem so they selectively quote the science to get an air of credibility but then don't report what the scientists who did the work say.

They want to give the impression that most climate scientists are wrong so they selectively quote numbers because the vast majority of data disagree with their opinions. The Met Office explained just how their results were manipulated by the media, in a response that starts (emphasis added):

Today the Mail on Sunday published a story written by David Rose entitled “Forget global warming – it’s Cycle 25 we need to worry about”.

This article includes numerous errors in the reporting of published peer reviewed science undertaken by the Met Office Hadley Centre and for Mr. Rose to suggest that the latest global temperatures available show no warming in the last 15 years is entirely misleading.

Science journalists who want to try to impartially and accurately report on science, informing their readership about the wonders of scientific endeavour, should not rely on the wild statements of politically motivated think tanks. Sound-bite 'science' is not proper skeptical science.

Climate change policy: Oil's tipping point has passed

Wed, 1 Feb 2012 01:24:41 EST

This is a reprint of a news release written by Sandra Hines and posted on the website of the University of Washington on Jan 26, 2012.

Stop wrangling over global warming and instead reduce fossil-fuel use for the sake of the global economy.

That’s the message from two scientists, one from the University of Washington and one from the University of Oxford in the United Kingdom, who say in the current issue of the journal Nature (Jan. 26) that the economic pain of a flattening oil supply will trump the environment as a reason to curb the use of fossil fuels.

“Given our fossil-fuel dependent economies, this is more urgent and has a shorter time frame than global climate change,” says James W. Murray, UW professor of oceanography, who wrote the Nature commentary with David King, director of Oxford’s Smith School of Enterprise and the Environment.

The “tipping point” for oil supply appears to have occurred around 2005, says Murray, who compared world crude oil production with world prices going back to 1998. Before 2005, supply of regular crude oil was elastic and increased in response to price increases. Since then, production appears to have hit a wall at 75 million barrels per day in spite of price increases of 15 percent each year.

“As a result, prices swing wildly in response to small changes in demand,” the co-authors wrote. “Others have remarked on this step change in the economies of oil around the year 2005, but the point needs to be lodged more firmly in the minds of policy makers.”

J Murray, U of Washington/D King, U of Oxford/Nature

Source: US Energy Information Administration Annual Energy Outlook 2011

For those who argue that oil reserves have been increasing, that more crude oil will be available in the future, the co-authors wrote: “The true volume of global proved reserves is clouded by secrecy; forecasts by state oil companies are not audited and appear to be exaggerated. More importantly, reserves often take 6 - 10 years to drill and develop before they become part of the supply, by which time older fields have become depleted.” Production at oil fields around the world is declining between 4.5 percent and 6.7 percent per year, they wrote.

“For the economy, it’s production that matters, not how much oil might be in the ground,” Murray says. In the U.S., for example, production as a percentage of total reserves went from 9 percent to 6 percent in the last 30 years.

“We’ve already gotten the easy oil, the oil that can be produced cheaply,” he says. “It used to be we’d drill a well and the oil would flow out, now we have to go through all these complicated and expensive procedures to produce the oil.”

The same is true of alternative sources such as tar sands or “fracking” for shale gas, Murray says, where supplies may be exaggerated and production is expensive. Take the promise of shale gas and oil: A New York Times investigative piece last June reported that “the gas may not be as easy and cheap to extract from shale formations deep underground as the companies are saying, according to hundreds of industry e-mails and internal documents and an analysis of data from thousands of wells.”

Production at shale gas wells can drop 60 to 90 percent in the first year of operation, according to a world expert on shale gas who was one of the sources for the commentary piece. Murray and King built their commentary using data and information from more than 15 international and U.S. government reports, peer-reviewed journal articles, reports from groups such as the National Research Council and Brookings Institution and association findings.

Stagnant oil supplies and volatile prices take a toll on the world economy. Of the 11 recessions in the U.S. since World War II, ten were preceded by a spike in oil prices, the commentary noted.

“Historically, there has been a tight link between oil production and global economic growth,” the co-authors wrote. “If oil production can’t grow, the implication is that the economy can’t grow either.”

Calculations from the International Monetary Fund, for example, say that to achieve a 4 percent growth in the global economy in the next five years, oil production must increase about 3 percent a year.

“Yet to achieve that will require either an heroic increase in oil production, ... increased efficiency of oil use, more energy-efficient growth or rapid substitution of other fuel sources,” according to the commentary.

“Economists and politicians continually debate policies that will lead to a return to economic growth. But because they have failed to recognize that the high price of energy is a central problem, they haven’t identified the necessary solutions: weaning society off fossil fuel.”

The commentary concludes: “This will be a decades-long transformation and we need to start immediately. Emphasizing the short-term economic imperative from oil prices must be enough to push governments into action now.”

Reference:

Nature Commentary: “Climate policy: Oil's tipping point has passed”, James Murray1 & David King

Nature, Volume 481, Pages: 433–435, 26 January 2012, doi:10.1038/481433a

The Latest Denialist Plea for Climate Change Inaction

Tue, 31 Jan 2012 05:42:14 EST

As they tend to do from time to time in an effort to distract from the climate science consensus, a group of scientists who are also climate "skeptics" have published an opinion-editorial (op-ed), trying to make the case against taking action to address climate change. As usual, the article is little more than a regurgitation of a number of climate myths we have debunked at Skeptical Science.

The signatories of this newest letter are also worth noting for their lack of noteworthiness. Although the climate denialist blogs have labeled them "luminaries" and "prominent scientists", the list is actually quite underwhelming. In fact, it only includes four scientists who have actually published climate research in peer-reviewed journals, and only two who have published climate research in the past three decades. Nearly half of the list (at least 7 of 16) have received fossil fuel industry funding, and the list also includes an economist, a physician, a chemist, an aerospace engineer, and an astronaut/politician. These are apparently the best and brightest the climate denialists can come up with these days?

Claude Allegre, former director of the Institute for the Study of the Earth, University of Paris
J. Scott Armstrong, cofounder of the Journal of Forecasting and the International Journal of Forecasting;
Jan Breslow, head of the Laboratory of Biochemical Genetics and Metabolism, Rockefeller University;
Roger Cohen, fellow, American Physical Society;
Edward David, member, National Academy of Engineering and National Academy of Sciences;
William Happer, professor of physics, Princeton;
Michael Kelly, professor of technology, University of Cambridge, U.K.;
William Kininmonth, former head of climate research at the Australian Bureau of Meteorology;
Richard Lindzen, professor of atmospheric sciences, MIT;
James McGrath, professor of chemistry, Virginia Technical University;
Rodney Nichols, former president and CEO of the New York Academy of Sciences;
Burt Rutan, aerospace engineer, designer of Voyager and SpaceShipOne;
Harrison H. Schmitt, Apollo 17 astronaut and former U.S. senator;
Nir Shaviv, professor of astrophysics, Hebrew University, Jerusalem;
Henk Tennekes, former director, Royal Dutch Meteorological Service;
Antonio Zichichi, president of the World Federation of Scientists, Geneva.

red - no climate science publications, member of at least one climate denialist group - GWPF (advisory board), George C. Marshall Institute (board of directors or roundtable speakers), Australian Climate Science Coalition (advisory panel), Heartland Institute (board of directors), and/or ExxonMobil

blue - published climate science research

orange - both a member of a climate denialist group and has published climate science research

black - no climate science publications or climate denialist group membership

Shaviv has published some research on galactic cosmic rays, and Kininmonth and Tennekes published a couple of climate-related papers in the 1970s (although most of Tennekes' research as been in aeronautics). Lindzen is the only climate scientist of note on the entire list, and is mainly noteworthy for his history of being wrong on climate issues.

The lack of expertise and numerous conflicts of interest aside, let's evaluate their arguments on their own merits (or more accurately, lack thereof).

Denying the Consensus

The op-ed begins with the wholly unsupported assertion that:

"...a large and growing number of distinguished scientists and engineers do not agree that drastic actions on global warming are needed."

The fact that only 16 scientists and engineers signed this letter casts serious doubt on this assertion. The fake skeptics were able to get ~100 signatories on a similar letter 5 years ago - this seems more like a small and dwindling number of fake skeptics. It's also worth noting that 255 National Academy of Science members (truly prominent scientists) signed an opposite letter, urging action to address climate change.

"We urge our policy-makers and the public to move forward immediately to address the causes of climate change, including the un-restrained burning of fossil fuels."

Moreover, why should we care what these few self-proclaimed "distinguished scientists and engineers" think we should do about climate change? If I need heart surgery, I'm not going to allow a dentist to perform it, even if it's the best dentist in the world. Virtually all of the climate science experts agree that actions to address global warming are needed. Their informed opinions are the ones we should heed when it comes to climate science, not those of astronauts and physicians.

Gish Gallop of Fake Facts

After making a number of unsubstantiated and false assertions about the "growing number" of climate "skeptics," the letter then lays out what they see as the evidence supporting their fake skepticism. In reality, it's the same sort of Gish Gallop we've come to expect from climate denialists.

Global Warming Continues

The first myth in the article is the well-worn "global warming stopped in [insert year]". In this case, the fake skeptics have inserted "the last 10 years." This myth is easily debunked with the escalator graphic (Figure 1).

Figure 1: BEST land-only surface temperature data (green) with linear trends applied to the timeframes 1973 to 1980, 1980 to 1988, 1988 to 1995, 1995 to 2001, 1998 to 2005, 2002 to 2010 (blue), and 1973 to 2010 (red).

Not-So-Missing Heat

The second myth is that Kevin Trenberth's quote-mined comment "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't" is an admission that global warming stopped. In reality, the quote simply referred to the fact that while the planet is warming, we do not have adequate global monitoring to determine where all the heat is going. However, recent research by Loeb et al. (2012) has concluded that there may no longer be any "missing heat," so this particular myth really has no leg to stand on.

Positive Feedbacks

The denialist op-ed continues to confuse the issue by claiming

"...the warming is only missing if one believes computer models where so-called feedbacks involving water vapor and clouds greatly amplify the small effect of CO2."

Aside from continuing to misunderstand that the "missing heat" is about having an inadequate global climate observational network (mainly because we don't have good measurements of deep ocean heat), observational data have demonstrated that water vapor, and likely clouds, are indeed positive feedbacks.

Earth Has Warmed as Expected

The fake skeptics then repeat one of Lindzen's favorite myths, that the Earth has warmed less than predicted by the IPCC. This is simply untrue - in fact, the IPCC climate predictions have been amongst the most accurate thus far, much better than Lindzen and his fellow fake skeptics have done (Figure 2).

Figure 2: Various global temperature projections vs. observations

CO2 is a Pollutant and Not Necessarily Beneficial for Plants

The op-ed then repeats the old "CO2 isn't a pollutant" myth. In reality, because its emissions endanger public health and welfare through its impacts on climate change, by definition CO2 is a pollutant according to the US Clean Air Act.

They couple this with the grossly oversimplistic "CO2 is plant food" myth. While it's true that in a controlled setting like a greenhouse, increased CO2 levels will generally improve plant growth, the global climate is not so simple. Increasing CO2 in the climate also changes temperatures, precipitation, drought and flood frequencies, and a number of other factors which impact plant growth.

The global increase of CO2 is a grand biological experiment, with countless complications that make the net effect of this increase very difficult to predict with any appreciable level of detail. To gloss over these complexities with the simplistic "CO2 is plant food" argument is an insult to the readers' intelligence. It also ignores the other adverse impacts of increasing CO2, like ocean acidification. Apparently these "concerned scientists" don't think very highly of their audience.

Follow the Money Indeed

Just when we thought the op-ed letter couldn't get worse, these fake skeptics have the gall to suggest that we "follow the money," because climate "alarmism" supposedly brings bountiful research funding, "an excuse for governments to raise taxes", "big donations" for environmental groups, and other similar tinfoil-hattery. Considering that at least 43% of the letter's signatories have received money from the fossil fuel industry, being given large sums of money just for being climate "skeptics" and publishing error-riddled nonsense like this op-ed, the sheer nerve it must have taken to make this "follow the money" argument is astounding. Do follow their advice: research the signatories of this letter and follow their money trail, which leads straight to the fossil fuel industry.

CO2 Limits Will Help the Economy

The "concerned scientists" then follow with the myth that CO2 limits will harm the economy. This particular myth is primarily based on ignoring the fact that failing to reduce greenhouse gas emissions will have a tremendous cost, much greater than the cost of action (Figure 3). Relative to the alternative (inaction and trying to adapt to the damaging consequnces of climate change), CO2 limits will help the economy. This is why there is a consensus among economists with expertise in climate that we should put a price on carbon emissions (Figure 4).

Figure 3: Approximate costs of climate action (green) and inaction (red) in 2100 and 2200. Sources: German Institute for Economic Research and Watkiss et al. 2005

Figure 4: New York University survey results of economists with climate expertise when asked under what circumstances the USA should reduce its emissions

The article references work by economist William Nordhaus to try and justify climate inaction. When we actually listen to what Nordhaus has to say, the picture looks very different:

"We’ve got to get together as a community of nations and impose restraints on greenhouse gas emissions and raise carbon prices. If not, we will be in one of those gloomy scenarios."

Although he tends to be quite conservative about the costs of climate change relative to other economists, Nordhaus still supports putting a price on carbon emissions. Nordhaus not appreciate his name being invoked to justify foolish calls for climate inaction, telling Andrew Revkin:

"The piece completely misrepresented my work. My work has long taken the view that policies to slow global warming would have net economic benefits, in the trillion of dollars of present value. This is true going back to work in the early 1990s (MIT Press, Yale Press, Science, PNAS, among others). I have advocated a carbon tax for many years as the best way to attack the issue. I can only assume they either completely ignorant of the economics on the issue or are willfully misstating my findings."

Is this the Best Climate "Skeptics" Can Do?

If we boil down this op-ed to its basics, we're left with a letter signed by only two scientists with peer-reviewed climate research publications in the past three decades, which exhibits a serious lack of understanding of basic climate concepts, and which simply regurgitates a Gish Gallop of long-worn climate myths. The letter claims that climate "skepticism" is growing, and yet only has 16 signatories, at least 43% of which have received funding from the fossil fuel industry, and not one single new argument which hasn't been long-debunked.

If this is the best today's climate fake skeptics can do, perhaps, as Patrick Michaels suggests, they are losing the battle. We can only hope that this is the case.

David Archibald Exaggerates the Solar Influence on Future Climate Change

Sun, 29 Jan 2012 12:03:33 EST

David Archibald is a climate "skeptic" who has been CEO of multiple oil and mineral exploration companies operating in Australia, and currently is part of the scientific advisory panel for the Australian Climate Science Coalition (ACSC) - a group of Australian fake skeptics which also includes Bob Carter, John McLean, David Evans, and Ian Plimer. Archibald is a major proponent of the "it's the sun" myth, and from time to time will publish a paper in Energy&Environment (the controversial journal which publishes "skeptic" research which is too erroneous to meet the standards in standard peer-reviewed journals), claiming that a decline in solar activity will lead to substantial cooling over the next few decades.

In this post we'll examine one such paper, Archibald (2009), in which Archibald claims that certain regions of the planet will cool 2.2°C over solar cycle 24, which began in December 2008, and is expected to be a relatively weak cycle (Figure 1).

Figure 1: Smoothed monthly sunspot number over the second half of solar cycle 23 and beginning of cycle 24 (blue) and the predicted values over the rest of cycle 24 (red) (NOAA).

However, as fellow ACSC member John McLean did with the influence of La Niña, David Archibald has grossly overestimated the solar influence on global temperature.

The Claim

As we at SkS have previously noted, Archibald has a history of focusing on data from individual surface temperature stations such as Perth, Australia or Bridgeport, Washington. In his 2009 paper, Archibald similarly focused on temperature data from a single temperature station in Hanover, New Hampshire:

"If the month of minimum for the Solar Cycle 23 to 24 transition is July 2009, this would make Solar Cycle 23 over thirteen years long. This in turn would mean that it would be 3.2 years longer than Solar Cycle 22, and imply that the annual average temperature of Hanover, New Hampshire will be 2.2° C cooler during Solar Cycle 24 than it had been on average over Solar Cycle 23."

In this quote, Archibald repeats the myth that solar cycle length determines global temperatures - a quite unphysical argument which is based on correlation rather than causation - and specifically focuses on the temperature data from a single station.

Hanover, New Hampshire

The temperature data for Hanover are available via NASA GISS. The average temperature in Hanover over solar cycle 23, which began in May 1996 and ended in December 2008, was 7.9°C. Thus if Archibald is correct, over solar cycle 24, the temperature in Hanover should cool to 5.7°C. In fact, Archibald's prediction is based on the average temperature over the entire solar cycle, so his prediction is actually that the average temperature in Hanover from approximately 2009 through 2020 will be 5.7°C.

Thus far we are more than a quarter of the way into cycle 24, and Archibald's prediction is not looking good (Figure 2). And remember that we're currently headed upwards toward the solar cycle maximum (expected in 2013 or 2014), so any dramatic solar-caused cooling will have to happen in the second half of the solar cycle.

Figure 2: GISS temperature record for Hanover, New Hampshire (1895 through 2008, black), GISS Hanover data for solar cycle 24 (2009 through 2011, green), and an example of how Hanover temperatures would have to change for Archibald's prediction to be accurate (blue).

As with John McLean's failed temperature prediction, a simple cursory glance at the data is all that's necessary to conclude that Archibald's prediction has no basis in reality. However, we haven't yet seen the worst of Archibald's predictions.

Mid-Latitude Temperatures

In the abstract of his paper, Archibald extends the claim much further yet:

"As at late 2008, the progression of the current 23/24 solar minimum indicates that a severe cool period is now inevitable, similar to that of the Dalton Minimum. A decline in average annual temperature of 2.2° C is here predicted for the mid-latitude regions over Solar Cycle 24."

"Mid-latitude regions" refers to the area betwen latitudes of approximately 24° and 64° in both the northern and southern hemispheres, which accounts for nearly half of the Earth's surface. Such a large area exhibits much less temperature variability, on average, than a single station like Hanover, New Hampshire. Thus Archibald's prediction in this case becomes even worse yet (Figure 3).

Figure 3: Mid-latitude (24 to 64°S and 24 to 64°N) GISS land-ocean temperature (black) vs. Archibald's prediction (blue).

The middle latitudes warmed approximately 0.77°C over the past 115 years, and Archibald has predicted that they will cool 2.2°C over the next 10 years. This prediction clearly has no basis in reality.

Manufacturing Controversy

A prediction of 2.2°C cooling for Hanover, New Hampshire may be unrealistic, but it also is of little consequence. However, 2.2°C cooling for nearly half the planet, or even the entire planet, would be quite noteworthy, to say the least. Towards the end of the paper, Archibald fuels speculation about such a possibility:

"Based on our understanding of the interaction of solar and terrestrial processes, the following projections are made for a number of climate-related physical processes:"

[...]

"Temperature Decline Solar Cycle 24: 2.2° C"

In this case, Archibald does not specify the geographic region to which his prediction applies, and it can easily be construed (or misconstrued) as referring to the planet as a whole. In fact, when the prediction inevitably fails, Archibald will undoubtedly claim that his assertion of 2.2°C cooling for "mid-latitude regions" was only intended to apply to very isolated regions like Hanover, New Hampshire.

However, imprecise assertions like "mid-latitude regions" and the unspecified "Temperature Decline" will allow fake skeptics to add David Archibald to the list of "scientists" who are "predicting global cooling," even though his research does not support this claim. In fact, 2.2°C is nearly half the average global temperature change during the transition between glacial and interglacial periods. If Archibald were predicting such a massive temperature change over a period on the order of a decade, he would deserve to be laughed out of the room.

Realistic Solar Influence

In reality, solar activity is generally quite stable. On a global scale, the sun has only contributed to less than 40% (0.3°C) of the observed global warming over the past century, and less than 15% (0.1°C) over the past 50 years, according to peer-reviewed global warming attribution research (Figure 4).

Figure 4: Solar contribution to global warming according to Meehl et al. 2004 (M04, blue), Stone et al. 2007 (S07, red), Lean and Rind 2008 (LR08, green), and Huber and Knutti 2011 (HK11, purple).

According to Fuelner and Rahmstorf (2010), even a grand solar minimum would cause no more than a 0.3°C cooling of average global surface temperatures. A recent study by Jones et al. (2012) concluded that similar to Archibald's assumption, solar activity will fall to levels similar to the Dalton Minimum during the 21st century, but unlike Archibald, found that this would only result in a minimal cooling effect of approximately 0.08°C on the average global surface temperature.

"...the likely reduction in the warming by 2100 is found to be between 0.06 and 0.1K, a very small fraction of the projected anthropogenic warming."

Bear in mind that according to various solar reconstructions (summarized in Jones et al. 2012), total solar irradiance (TSI) today is only between 1 and 2.5 Watts per square meter (W/m2) higher than during the Maunder Minimum, which was the period with the lowest solar activity in the past several centuries. The change since the Dalton Minimum is even smaller. The solar radiative forcing is estimated by multiplying the change in TSI by 0.25 and 0.7, to account for the sphericity and albdeo (reflectivity) of the Earth.

Thus the radiative forcing caused by a change in TSI from today's levels to Maunder Minimum levels would only cause a radiative forcing of 0.17 to 0.44 W/m2. This is the equivalent forcing to an increase of atmospheric CO2 from today's level of 390 parts per million (ppm) to between and 400 and 420 ppm - between 5 and 15 years of CO2 emissions at today's rates. A Dalton Minimum would correspond to just a few years of human CO2 emissions, and at most a couple tenths of a degree cooling of the average global surface temperature - a factor of 10 less than Archibald's claimed 2.2°C.

In short, Archibald has either dramatically overestimated the solar influence on global temperatures, or has worded his paper so poorly that his discussion of Hanover, New Hampshire temperatures can be misconstrued as referring to mid-latitude or global average temperatures. This sort of shoddy work is undoubtedly why Archibald was forced to settle for publication in Energy&Environment. The sun is simply not going to save us from the rapid global warming we have in store on our current emissions path.

Major Study of Ocean Acidification Helps Scientists Evaluate Effects of Atmospheric Carbon Dioxide on Marine Life

Mon, 6 Feb 2012 03:38:08 EST

This is a reprint of a news release posted (Jan 23, 2012) on the website of the University of California Santa Barbara.

Might a penguin's next meal be affected by the exhaust from your tailpipe? The answer may be yes, when you add your exhaust fumes to the total amount of carbon dioxide lofted into the atmosphere by humans since the industrial revolution. One-third of that carbon dioxide is absorbed by the world's oceans, making them more acidic and affecting marine life.

A UC Santa Barbara marine scientist and a team of 18 other researchers have reported results of the broadest worldwide study of ocean acidification to date. Acidification is known to be a direct result of the increasing amount of greenhouse gas emissions. The scientists used sensors developed at Scripps Institution of Oceanography at UC San Diego to measure the acidity of 15 ocean locations, including seawater in the Antarctic, and in temperate and tropical waters.

The image shows a SeaFET pH sensor deployed underneath approximately 12 feet of sea ice in McMurdo Sound, Ross Island, Antarctica, in Oct. 2010. Scientists use these sensors to identify the natural dynamics of ocean pH in order to better understand how marine organisms may be impacted by climate change. The black object is the sensor, which is anchored to the ocean bottom using weights. Along the ocean bottom, worms and sea stars are visible.
Credit: Rob Robbins

As oceans become more acidic, with a lower pH, marine organisms are stressed and entire ecosystems are affected, according to the scientists. Gretchen E. Hofmann, an eco-physiologist and professor in UCSB's Department of Ecology, Evolution & Marine Biology, is lead author of the recent article in PLoS ONE that describes the research.

"We were able to illustrate how parts of the world's oceans currently have different pH, and thus how they might respond to climate changes in the future," said Hofmann. "The sensors allowed us to capture that." The sensors recorded at least 30 days of continuous pH values in each area of the study.

UCSB graduate student Emily Rivest positions a SeaFET pH sensor in a coral reef off the island of Moorea, in French Polynesia. The large cement posts once held up a pier that toppled over the reef; one of the fallen posts provides an anchor for the sensor. The grey bottle is used to collect seawater samples for chemical analyses that augment the pH data. The reefs surrounding the island of Moorea are home to UCSB's Coral Reef Long-Term Ecological Research site (MCR LTER).
Credit: Anderson Mayfield

Since the beginning of the industrial revolution, human activities have accelerated the release of carbon dioxide into the atmosphere as carbon dioxide mixes with water. The two molecules combine to become carbonic acid, making seawater more acidic. As billions of molecules combine and go through this process, the overall pH of the oceans decreases, causing ocean acidification.

Acidification limits the amount of carbonate forms that are needed by marine invertebrates, such as coral, urchins, snails, and shellfish, to make their skeletons. As the concentration of carbonates decreases in acidified water, it is harder to make a shell. And, the structures of some organisms may dissolve when water chemistry becomes too unfavorable.

"The emerging pH data from sensors allows us to design lab experiments that have a present-day environmental context," said Hofmann. "The experiments will allow us to see how organisms are adapted now, and how they might respond to climate change in the future."

The video shows a SeaFET pH sensor deployed in the Ross Sea underneath approximately 12 feet of sea ice at Cape Evans, Antarctica. Scientists use these sensors to identify the natural dynamics of ocean pH in order to better understand how marine organisms may be impacted by climate change. Credit: Courtesy BRAVO134M

In this video, diver Steve Rupp visits a UCSB SeaFET sensor in very deep water under ice near McMurdo station, Antarctica. Credit: Courtesy BRAVO134M

Hofmann researched the Antarctic, where she has worked extensively, as well as an area of coral reefs around the South Pacific island of Moorea, where UCSB has a Long-Term Ecological Research (LTER) project. She also studied the coastal waters of Santa Barbara, in conjunction with UCSB's Santa Barbara Coastal LTER. The research team provided 30 days of pH data from other ocean areas around the world.

The researchers found that, in some places such as Antarctica and the Line Islands of the South Pacific, the range of pH variance is much more limited than in areas of the California coast that are subject to large vertical movements of water, known as upwellings. In some of the study areas, the researchers found that the decrease in seawater pH being caused by greenhouse gas emissions is still within the bounds of natural pH fluctuation. Other areas already experience daily acidity levels that scientists had expected would only be reached at the end of this century.

"This study is important for identifying the complexity of the ocean acidification problem around the globe," said co-author Jennifer Smith, a marine biologist with Scripps. "Our data show such huge variability in seawater pH, both within and across marine ecosystems, making global predictions of the impacts of ocean acidification a big challenge."

Todd Martz, a marine chemistry researcher at Scripps, developed the sensor. "When I arrived at Scripps, we re-engineered my prototype design, and since then I have not been able to keep up with all of the requests for sensors," said Martz. "Because every sensor used in this study was built at Scripps, I was in a unique position to assimilate a number of datasets, collected independently by researchers who otherwise would not have been in communication with each other. Each time someone deployed a sensor, they would send me the data, and eventually it became clear that a synthesis should be done to cross-compare this diverse collection of measurements." Hoffman worked with Martz to put together the research team to create that synthesis.

The team noted that the Scripps sensors, called "SeaFET" and "SeapHOx," allow researchers to continuously and autonomously monitor pH from remote parts of the world, providing important baselines from which scientists can monitor future changes caused by ocean acidification.

Despite surveying 15 different ocean regions, the authors noted that they only made observations on coastal surface oceans, and that more study is needed in deeper ocean regions farther away from land.

Hofmann is the director of the Center for the Study of Ocean Acidification and Ocean Change, a UC multi-campus initiative. Hofmann participated in writing a report on ocean acidification while on the National Research Council's Ocean Acidification Committee, and she is currently participating as a lead author on the National Climate Assessment. Hofmann is a member of the National Science Foundation's Office of Polar Programs Advisory Panel, and she is an Aldo Leopold Fellow.

In addition to Hofmann, Martz, and Smith, co-authors include Emily B. Rivest and Pauline Yu of UCSB; Uwe Send, Lisa Levin, Yuichiro Takeshita, Nichole N. Price, Brittany Peterson, and Christina A. Frieder of Scripps; Paul Matson and Kenneth Johnson of the Monterey Bay Aquarium Research Institute; Fiorenza Micheli and Kristy Kroeker of Stanford University; Adina Paytan and Elizabeth Derse Crook of UC Santa Cruz; and Maria Cristina Gambi of Stazione Zoologica Anton Dohrn in Naples, Italy.

Funding for instrument development and related field work came from several sources, including the National Science Foundation, the David and Lucile Packard Foundation, the University of California, the Gordon and Betty Moore Foundation, the Nature Conservancy, the WWW Foundation, Scott and Karin Wilson, the Rhodes family, and NOAA.

NASA scientists expect more rapid global warming in the very near future (part 2)

Sun, 5 Feb 2012 19:00:08 EST

In part 1 we saw that NASA scientists James Hansen, Reto Ruedy, Makiko Sato and Kwok-Wai Ken Lo from the Goddard Institute for Space Studies (GISS) have released an analysis of global temperature in 2011, and looked at future prospects. Reviewing the evidence, the authors concluded that rapid global warming is likely in the next few years. This is not a new phenomenon, but simply a reflection of natural variability, cool (La Niña) and warm (El Niño) phases which still exert a temporary cooling/warming influence on global surface temperatures even in the presence of a persistent global warming trend.

In part 2 we'll see that seasonal extreme warm anomalies in 2009-2011 are well above the 1951-1980 base period typically used in GISTEMP analyses - indicative of global warming's role in heatwaves. That measuring of manmade aerosols (pollution particles that reflect sunlight) is still highly problematic, and significantly, that the current warming phase of the 11-year solar cycle is likely to have a noticable warming effect on the climate over the next 3-5 years.

Figure 1 -Solar irradiance from composite satellite-based time series. Data sources: For 1976/01/05 to 2011/02/02 Physikalisch Meteorologisches Observatorium Davos, World Radiation Center and for 2011/02/03 to 2012/01/11 University of Colorado Solar Radiation & Climate Experiment. The circled area is (roughly) the solar energy already absorbed by the ocean and yet to manifest itself in global temperatures i.e - warming already committed.

Damn statistics

As detailed in the SkS post on the freak 2010 Moscow heatwave, global temperatures follow what is called a Gaussian or normal distribution. That is, if you plot temperature along two axes their frequency or density (vertical axis) and how far these temperature measurements deviate from the mean or average (horizontal axis), will tend to be clustered around the mean. These observations or values resemble a bell-shaped curve. See figure 2.

Figure 2 - illustration of a Normal/Gaussian distribution

Not all climate-related phenomena follow this Gaussian distribution, but a number of studies show that surface temperatures do. Intuitively this makes sense, because although surface temperatures can exhibit large swings from time to time they generally don't deviate much from the average throughout the year.

Because of the shape of this distribution, one can mathematically determine the spread of the values. This is known as the 68-95-99.7, three-sigma, or empirical rule, where the percentage of a particluar value declines as one moves further away from the mean. 68.2% of all values are within one standard deviation of the mean, 95.4% within two standard deviations, and 99.7% within 3 standard deviations. See figure 3, and note the greek symbol is sigma representing a standard deviation.

Figure 3 - Gaussian distribution with standard deviations.

With a warming climate the mean temperature begins to slowly climb too, so the bell-shaped curve creeps to the right in the warming direction (figure 4). As it does so, you can see how it affects the measurements at the extremes - warm extreme temperatures become more common place, and cold extremes less common. A shifting mean (as in warming global temperatures) leads to large changes at the extremes.

Fig 4 - illustration of gaussian distribution with a shifting mean.

Seasonal mean temperature anomalies

The authors look at the seasonal anomalies for both June-August (figure 5), the Northern Hemisphere summer, and December-February (figure 6), the Northern Hemisphere winter, for not only 2011, but 2009 and 2010 also. These anomalies (changes from a baseline temperature) are compared to the base period of 1951-1980 in the GISTEMP temperature series - which is the typical base period for GISS.

They compare the surface temperature anomalies in two ways, firstly by plotting the anomalies in °C (figures 5a and 6a), and secondly by plotting them in units of the standard deviation (5b and 6b).

Figure 5 - June-August surface temperature anomalies in 2009-2011 in units of °C (a), and in units of the local standard deviation of local seasonal-mean temperature (b).

In 2010 the monster summer Moscow heatwave is readily visible (circled), as is the summer heatwave covering Texas, Oklahoma and Northern Mexico in 2011 (also circled). Looking at the global temperature in the form of standard deviations is very revealing. Those dark brown areas in 5(b) are 3 standard deviations (3 sigma) or larger (refer figure 3) - very rare extremely warm episodes. These June-to-August extreme warm events in the base period (1951-1980) were a few tenths of one percent, however by 2009 they rose to 7%, 13% in 2010 and 9% in 2011.

This greater-than-tenfold increase in the warm extremes led the authors to state:

"Increased occurrence of such extreme anomalies as a result of global warming, by more than a factor of 10, implies that we can attribute such recent extreme anomalies, including that in Texas and Oklahoma, to global warming"

To appreciate this one only has to look at figure 4, where the slowly shifting mean (global warming) causes a dramatic increase in extreme warm events (heatwaves).

Figure 6. December-February surface temperature anomalies 2009-2011 in units of °C (a), and in units of the local standard deviation of local seasonal-mean temperature(b).

For December-February, the cold winters in the USA and Europe in 2010 and 2011 are very evident in figure 6a (°C anomalies), however once again looking at them in the form of standard deviations gives a better indication of the overall picture. The great majority of these cold events were only minus 1 standard deviation (-1 sigma) away from the mean (light blue). 2010 & 2011 were cold in these regions even by 1951-1980 standards (the baseline), but because they mostly fall within minus one standard deviation (see figure 3), it was a level of cold that occurred reasonably often back then.

Temperature extremes over these years is basically in line with what is expected under global warming - an increase in extremely warm episodes and a decline in extremely cold ones. Indeed looking at the 3 years (2009-2011) only one small region of the tropical ocean in 2011 exceeds minus three standard deviations (-3 sigma), whereas warm extremes (+3 standard deviations) occur with regularity in each year.

The Arctic Oscillation

The Arctic Oscillation (AO) Index is a record summarizing the state of the Arctic weather. Winds that circle the Arctic keep the cold bottled up there, rather like a closed fridge door. When these winds weaken the potential exists for cold Arctic air to escape and get pushed further south. This is simlar to leaving the fridge door open - the cold air escapes.

The AO has no predictive power, as stated earlier it is just a record of the weather there. But looking at the AO index is revealing in that it demonstrates both the long-term trend and just how extreme the 2009-2010 and 2010-2011 Arctic weather was. The long-term trend (Figure 7) has been one of a more positive AO (stronger zonal winds around the Arctic), which indicates less likelihood of cold outbreaks, but the two winters in question were extreme departures from this trend. 2009-2010 was the strongest negative anomaly (weak zonal winds) in over a century of recordkeeping.

Fig 7. Arctic Oscillation (AO) index. Negative values indicates high pressure in the polar region and thus a tendency for weak zonal winds that facilitate cold air outbreaks to middle latitudes. Blue line is the monthly mean and red line is the 60-month (5-year) running mean.

The authors state:

"Although there has been speculation about possible effects of reduced Arctic sea ice on outbreaks of Arctic air, Fig.(7) provides little support for that hypothesis. Several years had low sea ice cover in the past decade, yet most of those years were warm at middle latitude winters by 1951-1980 standards. Given the fact that winters are much "noisier" (greater natural variability) than summers, the past two unusually cool winters in the United States and Europe do not alter the expectation that middle latitude winters will tend to become warmer as global warming continues."

The Solar Cycle

Small fluctuations in the sun's output occur over a roughly 11-year cycle (peak-to-peak) and vary by as much as 0.25 watts per square metre(W/m2). This may sound sound small, but it's rather substantial when compared to Earth's energy imbalance - that is: the difference between energy (heat) entering and leaving Earth's atmosphere - the global warming-caused imbalance.

The NASA analysis has this imbalance at 0.58±0.15 W/m2 (Hansen 2011), whereas Loeb (2012) has it at 0.50±0.43W/m2. Either way the solar cycle-induced change in energy received from the sun (0.25 W/m2) is large compared to Earth's energy imbalance.

Because of the ocean's thermal inertia (it takes a long time to warm up), global temperature change caused by the sun's variabilty lags solar irradiance by about 18 months. The 'trough' in the solar cycle (figure 1) was therefore still exerting a cooling influence on surface temperatures in 2011. However this is expected to quickly change to a warming effect over the next 3-5 years because the sun is on its ascent to the peak of the next cycle. As circled in figure 1 - extra sunlight has gone into the oceans in the last 18 months. This warming is a 'train that has already left the station' so-to-speak, and will soon manifest itself in global temperature.

Aerosols

These are tiny airborne manmade particles of pollution which reflect sunlight back out to space before it can warm the Earth's surface. The cooling effect from this aerosol forcing is thought to be about half that of greenhouse gases, but in the opposing (cooling) direction.

SkS has looked at another study (Kaufmann [2011]) which suggested an increase in aerosol forcing (greater cooling) due to the rapid industrialization in China in the last decade, however we don't have any direct and accurate global observations yet to support this. A satellite that was launched in 2011 was to be the first to make accurate measurements of this global aerosol effect, but it crashed into the ocean shortly after lift off.

This leads the authors to lament that aerosols are practically unmeasured on a global scale, and the authors regard them as a 'wild card'.

A warm near-term future

To sum up:

Global warming is a small but persistent trend that has significant impacts upon the Earth's climate.

2011 was the 9th warmest year in the GISTEMP global temperature series. 9 out of the 10 warmest years ocurred in the 21st century. The exception being 1998 - warmed by the largest El Niño in a century.

A more than tenfold increase in extreme warm events, has the authors state that we can attribute the monster 2010 Moscow summer heatwave, and the 2011 Oklahoma/Texas heatwave, to global warming.

The cold winters of 2009-2010 and 2010-2011 in the USA and Europe took place while the rest of the Northern Hemisphere (and planet) was anomalously warm. See also Guirguis (2011).

This NASA analysis highlights that the recent lull in surface temperatures is simply the result of natural variability superimposed upon the global warming trend - the cool phase of a cool/warm oscillation.

This natural variability is large enough to disguise the global warming trend when viewed over short intervals. See SkS post: Going down the up escalator.

Due to a combination of the warm phase of the solar cycle and an overdue switch to El Niño - when the ocean gives up a lot of heat to the atmosphere, near-future warming is expected.

The authors finish off their analysis by stating:

"We conclude that the slowdown of warming is likely to prove illusory, with more rapid warming appearing over the next few years."