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Explaining climate change science & rebutting global warming misinformation

Scientific skepticism is healthy. Scientists should always challenge themselves to improve their understanding. Yet this isn't what happens with climate change denial. Skeptics vigorously criticise any evidence that supports man-made global warming and yet embrace any argument, op-ed, blog or study that purports to refute global warming. This website gets skeptical about global warming skepticism. Do their arguments have any scientific basis? What does the peer reviewed scientific literature say?

 


PBL survey shows strong scientific consensus that global warming is largely driven by greenhouse gases

Posted on 5 August 2015 by Bart Verheggen

This is a guest post, republished from Bart Verheggen's blog My View on Climate Change.

As Michael Tobis rightly points out, the level of scientific consensus that you find “depends crucially on who you include as a scientist, what question you are asking, and how you go about asking it”. And on how you interpret the data. We argued that our survey results show a strong scientific consensus that global warming is predominantly caused by anthropogenic greenhouse gases. Others beg to differ. Recent differences of opinion are rooted in different interpretations of the data. Our interpretation is based on how we went about asking certain questions and what the responses indicate.

To quantify the level of agreement with a certain position, it makes most sense to look at the number of people as a fraction of those who answered the question. We asked respondents two questions about attribution of global warming (Q1 asking for a quantitative estimate and Q3 asking for a qualitative estimate; the complete set of survey questions is available here). However, as we wrote in the ES&T paper:

Undetermined responses (unknown, I do not know, other) were much more prevalent for Q1 (22%) than for Q3 (4%); presumably because the quantitative question (Q1) was considered more difficult to answer. This explanation was confirmed by the open comments under Q1 given by those with an undetermined answer: 100 out of 129 comments (78%) mentioned that this was a difficult question.

There are two ways of expressing the level of consensus, based on these data: as a fraction of the total number of respondents (including undetermined responses), or as a fraction of the number of respondents who gave a quantitative or qualitative judgment (excluding undetermined answers). The former estimate cannot exceed 78% based on Q1, since 22% of respondents gave an undetermined answer. A ratio expressed this way gives the appearance of a lower level of agreement. However, this is a consequence of the question being difficult to answer, due to the level of precision in the answer options, rather than it being a sign of less agreement.

Moreover, the results in terms of level of agreement based on Q1 and Q3 are mutually consistent with each other if the undetermined responses are omitted in calculating the ratio; they differ markedly when undetermined responses are included. In the supporting information we provided a table (reproduced below) with results for the level of agreement calculated either as a fraction of the total (i.e., including the undetermined answers) or as a fraction of those who expressed an opinion (i.e., excluding the undetermined answers), specified for different subgroups.

Verheggen et al - EST 2014 - Table S3

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The most influential climate change papers of all time

Posted on 4 August 2015 by Guest Author

This is a re-post from Roz Pidcock at Carbon Brief

Which of the many thousands of papers on climate change published each year in scientific journals are the most successful? Which ones have done the most to advance scientists' understanding, alter the course of climate change research, or inspire future generations?

On Wednesday, Carbon Brief will reveal the results of our analysis into which scientific papers on the topic of climate change are the most "cited". That means, how many times other scientists have mentioned them in their own published research. It's a pretty good measure of how much impact a paper has had in the science world.

But there are other ways to measure influence. Before we reveal the figures on the most-cited research, Carbon Brief has asked climate experts what they think are the most influential papers.

We asked all the coordinating lead authors, lead authors and review editors on the last Intergovernmental Panel on Climate Change (IPCC) report to nominate three papers from any time in history. This is the exact question we posed:

"What do you consider to be the three most influential papers in the field of climate change?"

As you might expect from a broad mix of physical scientists, economists, social scientists and policy experts, the nominations spanned a range of topics and historical periods, capturing some of the great climate pioneers and the very latest climate economics research.

Here's a link to our summary of who said what. But one paper clearly takes the top spot.

Winner: Manabe & Wetherald (1967)

With eight nominations, a seminal paper by Syukuro Manabe and Richard. T. Wetherald published in the Journal of the Atmospheric Sciences in 1967 tops the Carbon Brief poll as the IPCC scientists' top choice for the most influential climate change paper of all time.

Entitled, "Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity", the work was the first to represent the fundamental elements of the Earth's climate in a computer model, and to explore what doubling carbon dioxide (CO2) would do to global temperature.

Fig1  Manabe & Wetherald (1967), Journal of the Atmospheric Sciences

The Manabe & Wetherald paper is considered by many as a pioneering effort in the field of climate modelling, one that effectively opened the door to projecting future climate change. And the value of climate sensitivity is something climate scientists are still grappling with today.

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Statistics says the long-term global warming trend continues

Posted on 3 August 2015 by John Abraham

A new study has just been prepared for an upcoming climate meeting of the US Climate Variability and Predictability Program. This group has an annual summit and this year will have a special science session with papers and presentations devoted to the so-called “hiatus”. The “hiatus” has taken many meanings. In the popular press, it is often used to falsely claim that global warming stopped. As I’ve written many times, global warming has not stopped; the Earth has been continuing to gain energy because of human emissions of greenhouse gases.

In other cases, the “hiatus” refers to a reported slowdown in temperature increases. This too is not seen in the ocean data or in sea level rise. It is only seen in surface temperatures (temperatures of the surface of land and ocean regions). 

What my colleague and I wanted to know was, is this slowdown real or not? Specifically, we wanted to know whether it passed mathematical tests for statistical significance. My colleague, who is an expert is statistics, and operates a climate website, downloaded the surface temperature data from NASA and detrended it (removed the long term increase in temperatures). The difference between the red trendline and the black dots is called the residual. We wanted to increase the odds that we would find a “hiatus” by stopping our analysis in 2013 (omitted the hottest year on record, 2014).

fig 1

NASA temperature anomalies from Foster and Abraham, 2015.

If you plot the residual over this time period, it looks like the image below.

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7 comments


2015 SkS Weekly Digest #31

Posted on 2 August 2015 by John Hartz

Contents: SkS Highlights, Improving the Weekly Digest, Toon of the Week, Quote of the Week, They Said What?: GOP Presidential Hopefuls, SkS in the News, SkS Spotlights: Asset Owners Disclosure Project, Poster of the Week, Coming Soon on SkS, and 97 Hours of Consensus: Dr. Pietr Sans

SkS Highlights

Conspiracy theories about Skeptical Science by John Cook drew the highest number of comments of the aarticles posted on SkS during the past week. Coming in second and thrid respectively were: 

Improving the Weekly Digest

The all-volunteer SkS author team is engaged in finding ways to improve the Wekly Digest in order to make it more attractive and useful to all of our readers. We would like your input and continuing particpation in this effort. In this context:

  • If you were responsible for producing the Weekly Digest, what changes would you make to its syle and content? 

Toon of the Week

 2015 Toon 31

Quote of the Week

Savio Carvalho of Amnesty International (AI), which is part of the UNMG, told IPS the post-2015 agenda has become an aspirational text sans clear independent mechanisms for people to hold governments to account for implementation and follow-up.

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2015 SkS Weekly News Roundup #31D

Posted on 2 August 2015 by John Hartz

Climate models are even more accurate than you thought

Global climate models aren’t given nearly enough credit for their accurate global temperature change projections. As the 2014 IPCC report showed, observed global surface temperature changes have been within the range of climate model simulations.

Now a new study shows that the models were even more accurate than previously thought. In previous evaluations like the one done by the IPCC, climate model simulations of global surface air temperature were compared to global surface temperature observational records like HadCRUT4. However, over the oceans, HadCRUT4 uses sea surface temperatures rather than air temperatures.

Climate models are even more accurate than you thought by Dana Nuccitelli, Climate Consensus-the 97%, The Guardian, July 31, 2015


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Indonesian translation of The Debunking Handbook

Posted on 1 August 2015 by BaerbelW

The Debunking Handbook is now available in Indonesian. Many thanks to Herendraswari Kusumawardani who did this 10th(!) translation of the handbook.

Note to other translators:

If you'd like to translate the Debunking Handbook into another language, please contact us (select "Enquiry about translations" from the drop-down list) to ensure nobody else is already working on your language. Then download this Word document which has all the English text in one column and a blank column in which to place the translated text. Once complete, send us back the document and we'll insert the translated text into the existing design. The already available translations can be found on this page.

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2015 SkS Weekly News Roundup #31C

Posted on 1 August 2015 by John Hartz

Climate pressures lead to rise in 'new-age orphans' in India's delta

Eleven-year old Srijita Bhangi sits in the waiting room of the jetty boat that connects her island home in Khulna to the mainland Sundarbans, near India's border with Bangladesh.

After spending a few days with her elderly grandparents - an effort to lift her most recent spell of depression - she is travelling back to the school hostel where she has lived since her parents left two years ago to find work in a garment factory 1,000 kilometres (620 miles) away, in Tamil Nadu.

Since then she has seen them only once, and the school lodging has effectively become her new home.

Climate pressures lead to rise in 'new-age orphans' in India's delta by Aditya Ghosh, Thomson Reuters Foundation, July 30, 2015


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Climate models are even more accurate than you thought

Posted on 31 July 2015 by dana1981

Global climate models aren’t given nearly enough credit for their accurate global temperature change projections. As the 2014 IPCC report showed, observed global surface temperature changes have been within the range of climate model simulations.

Now a new study shows that the models were even more accurate than previously thought. In previous evaluations like the one done by the IPCC, climate model simulations of global surface air temperature were compared to global surface temperature observational records like HadCRUT4. However, over the oceans, HadCRUT4 uses sea surface temperatures rather than air temperatures.

diagram

A depiction of how global temperatures calculated from models use air temperatures above the ocean surface (right frame), while observations are based on the water temperature in the top few metres (left frame). Created by Kevin Cowtan.

Thus looking at modeled air temperatures and HadCRUT4 observations isn’t quite an apples-to-apples comparison for the oceans. As it turns out, sea surface temperatures haven’t been warming fast as marine air temperatures, so this comparison introduces a bias that makes the observations look cooler than the model simulations. In reality, the comparisons weren’t quite correct. As lead author Kevin Cowtan told me,

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9 comments


10 Things We Learnt From Reddit About Understanding Climate Change

Posted on 30 July 2015 by Guest Author

This is a re-post from DeSmogBlog by Kyla Mandel

Two professors of cognitive psychology – Stephan Lewandowsky, from the University of Bristol, and Klaus Oberauer, from the University of Zurich – did a Reddit AMA (ask me anything) this week.

The topic up for discussion was: “The conflict between our brains and our globe: How will we meet the challenges of the 21st century despite our cognitive limitations?”

Climate change was (unsurprisingly) brought up repeatedly. Here are 10 things we learnt about understanding climate change:

1. Climate change is a BIG problem

Let’s face it: even the most optimistic among us can be overwhelmed by the sheer scale of what it means to tackle climate change. How can we push past this barrier?

I think [this is] a core problem about climate change: Even people who are willing to accept the scientific evidence are paralysed by the enormity of the task,” Lewandowsky said.

If you scare people without offering a solution then they manage their fear by denying the problem. So, the most important thing is to reinforce that there are solutions and that little steps do add up to something in the end. The situation is serious, yes, but in my view it is not hopeless.”

But what about the notion that yes, climate change exists, but we don’t need to worry because we’ll find ways to 'live with it'?

Unfortunately, it’s not that easy. There are certain aspects of climate change that will affect us all and “transcend boundaries,” Lewandowsky answered. This includes sea-level rise, extreme weather events such as flooding and drought, along with the spread of vector-borne diseases and mass migration.

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3 comments


2015 SkS Weekly News Roundup #31B

Posted on 29 July 2015 by John Hartz

2015 Arctic melting season won't break records, but could wipe the 'recovery'

Following the post of my colleague, Dana Nuccitelli on misreporting of ice trends, this article is a timely guest post by Neven Acropolis who runs the Arctic Sea Ice blog. - John Abraham

After the record smashing 2012 melting season had ended, Arctic sea ice watchers awaited the following melting season with a mix of anticipation and apprehension. Anticipation, because the annual ebb and flow of Arctic sea ice is one of the most spectacular natural events on the planet, accentuated by the dramatic loss of the past 30 years. Apprehension, because further losses would bring the Arctic yet one step closer to virtually ice-free conditions, an iconic image entailing many unpredictable consequences.

But just as the previous record low reached in 2007 was followed by a short-lived rebound, the 2013 melting season proved to be sufficiently cold and cloudy to make up for the large amount of thin first year ice in the Arctic. When the following 2014 melting season was relatively cold again, with little wind to compact the ice and transport it to lower latitudes, extent and area numbers yet again ended up well above 2012 levels. Consequently, this year’s melting seasonstarted out with more volume and more multi-year ice.

2015 Arctic melting season won't break records, but could wipe the 'recovery' by Neven Acropolis, Climate Consensus-the 97%, The Guardian, July 29, 2015


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2015 Arctic melting season won't break records, but could wipe the 'recovery'

Posted on 29 July 2015 by Neven

After the record smashing 2012 melting season had ended, Arctic sea ice watchers awaited the following melting season with a mix of anticipation and apprehension. Anticipation, because the annual ebb and flow of Arctic sea ice is one of the most spectacular natural events on the planet, accentuated by the dramatic loss of the past 30 years. Apprehension, because further losses would bring the Arctic yet one step closer to virtually ice-free conditions, an iconic image entailing many unpredictable consequences.

sea ice concentration

Arctic sea ice concentration on July 26, 2015. Source: University of Bremen.

But just as the previous record low reached in 2007 was followed by a short-lived rebound, the 2013 melting season proved to be sufficiently cold and cloudy to make up for the large amount of thin first year ice in the Arctic. When the following 2014 melting season was relatively cold again, with little wind to compact the ice and transport it to lower latitudes, extent and area numbers yet again ended up well above 2012 levels. Consequently, this year’s melting seasonstarted out with more volume and more multi-year ice.

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10 comments


2015 SkS Weekly News Roundup #31A

Posted on 28 July 2015 by John Hartz

40 percent of adults on Earth have never heard of climate change

A major concern for climate activists is figuring out what drives the public’s beliefs about climate change. This information can help scientists better engage with the public and help activists understand what factors are likely to make people take climate change seriously as a threat.

Until now, most research into public attitudes on climate change have focused on Western nations, like the United States, Europe and Australia, leaving scientists with little knowledge of how much awareness there is about climate change in other parts of the world and how people feel about it. But a new study, published Monday in the journal Nature Climate Change, provides a more inclusive look at the issue, giving scientists greater insight into what factors are most likely to make people care about climate change — if they know it’s happening at all.

The study focused on two major questions: what factors most influence whether a person is aware of climate change and, for those that know it’s happening, what factors influence how big of a risk that person thinks it poses. The researchers found that, worldwide, education is the biggest predictor of climate change awareness. Major factors that affected a person’s risk perception included understanding that climate change is caused by humans — this was especially true in the Americas and Europe — and noticing local changes in temperature, a particularly high indicator in many countries in Africa and Asia.

40 percent of adults on Earth have never heard of climate change by Chelsea Harvey, Energy & Environment, Washington Post, July 27, 2015


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The Daily Mail and Telegraph get it wrong on Arctic sea ice, again

Posted on 28 July 2015 by dana1981

Cherry-picking is one of the five telltale techniques of climate change denial. By focusing on short-term blips in noisy data, those who want to maintain the status quo can distract from the long-term threats posed by climate change. Climate contrarians most frequently deploy this strategy using global temperature and Arctic sea ice data.

A recent study in Nature Geoscience concluded that, not surprisingly, there is a strong relationship between the summer temperatures in the Arctic (specifically the number of “melting degree days”), and the amount of sea ice that melts in a given year. 2013 happened to be a relatively cool year in the Arctic – the coolest since 2004. As a result, there was relatively little ice melt in 2013. The annual minimum Arctic sea ice extent and volume were their largest since at least 2009, or perhaps as far back as 2005, according to the data used in this new study.

The following figure from the paper is as clear as ice – while there was a short-term increase from 2012 to 2013, the Arctic has lost more than half its sea ice over the past three decades.

sea ice volume

PIOMAS model Arctic sea ice volume for autumn 1980–2014 (solid line) and spring 1981–2014 (dashed line). CryoSat-2 volume estimates (red stars) are plotted for 2010–2014.

The following video by programmer Andy Lee Robinson also illustrates the dramatic rate of sea ice decline over the past 35 years.

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2015 SkS Weekly News Roundup #30D

Posted on 27 July 2015 by John Hartz

5 bold and beautiful solar projects from around the world

China is building its largest solar plant covering 6,301 acres in the Gobi desert and with capacity to provide electricity to 1 million households.

This is just another record breaker for China. But there’s good reason.

In a recent Greenpeace East Asia investigation, we found that air pollution levels have improved in the first six months of 2015, though still remain below global and domestic standards. Once completed the new solar plant will cut standard coal use by 4.26 million tons every year, reducing emissions of carbon dioxide and sulfur dioxide by 896,000 tons and 8,080 tons, respectively, according to state-run Xinhua news agency.

It’s part of a global trend. Check out these other bold and beautiful solar projects from around the world. Which one is your favorite?

5 Bold and Beautiful Solar Projects From Around the World by Shuk-Wah Chung, Greenpeace East Asia, EcoWatch, July 24, 2015


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Conspiracy theories about Skeptical Science

Posted on 27 July 2015 by John Cook

There is a growing body of research linking climate science denial and conspiratorial thinking. While Stephan Lewandowsky's Moon Landing paper has attracted most of the attention, another important paper from Yale University has flown somewhat under the radar. This research found that when those who deny climate change are asked to name the first thing that came to mind regarding climate change, the most common type of response involved conspiracy theories.

Smith_conspiracy.jpg

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20 comments


2015 SkS Weekly Digest #30

Posted on 26 July 2015 by John Hartz

SkS Highlights

The importance of good climate communication: a recent Arctic example by John Mason attracted the highest number of comments of the articles posted on SkS during the past week. Global warming deniers are an endangered species by Dana drew the second highest number of comments. 

Quote of the Week

Climate deniers who claim that thousands of scientists are engaging in a global fraud are "one step way from a conspiracy theory" that is too fantastical to be even feasible, he added.

"Think about it. We have an administration that could not roll out a proper health care website. You think they can manage a global scientific conspiracy? They could not do it if they wanted to," said Titley*, who also holds a doctorate in meteorology. And he scoffed at the idea that scientists are deliberately lying about climate change just to obtain short-term research grants.

*David Titley, Ret. Rear Adm., U.S Navy 

Navy climate change expert sees opponents ignoring science by Brian Nearing, Times Union (Albany, NY), July 22, 2015 

Toon of the Week

2015 Toon 30 

Hat tip to I Heart Climate Scientists 

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2015 SkS Weekly News Roundup #30C

Posted on 25 July 2015 by John Hartz

A new climate-change danger zone?

w much does the climate have to change for it to be “dangerous”? This question has vexed scientists ever since the first climate models were developed, back in the nineteen-seventies. It was provisionally answered in 2009, though by politicians rather than scientists. According to an agreement known as the Copenhagen Accord, which was brokered by President Barack Obama, to avoid danger, the world needs “to hold the increase in global temperature below 2 degrees Celsius” (3.6 degrees Fahrenheit).

Now a group of climate modellers is arguing that the danger point is, in fact, a lot lower than that. In a paper set to appear online this week in Atmospheric Chemistry and Physics, the modellers, led by James Hansen, the former director of NASA’s Goddard Institute for Space Studies, warn that an increase of two degrees Celsius could still be enough to melt large portions of Antarctica, which, in turn, could result in several metres’ worth of sea-level rise in a matter of decades. What’s important about the paper from a layperson’s perspective—besides the fate of the world’s major coastal cities, many of which would be swamped if the oceans rose that high—is that it shows just how far from resolved, scientifically speaking, the question of danger levels remains. And this has important political implications, though it seems doubtful that politicians will heed them.

A new climate-change danger zone? by Elizabeth Kolbert, The New Yorker, July 23, 2015


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Scientific consensus and arguments from authority

Posted on 24 July 2015 by Guest Author

This is a re-post of Potholer's latest YouTube video

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2015 SkS Weekly News Roundup #30B

Posted on 23 July 2015 by John Hartz

Climate treaty's finances on shaky ground

Faith in the Green Climate Fund, the finance arm long believed to hold a key to achieving a global climate change accord in Paris in December, is beginning to wane.

The Green Climate Fund is supposed to be the primary distributor of tens of billions of dollars in climate aid to help the world's poorest countries deal with climate change caused primarily by the actions of others. It was designed to help heal the deep divisions between rich and poor nations that have long dimmed hopes for a meaningful global warming solution. 

But with just one more board meeting to go before the Paris climate talks begin, the money it has to work with is not close to what's needed, the $3 billion contribution from the United States is looking iffy, and the fund has partnered with several financial institutions that developing nations distrust. 

Climate Treaty's Finances on Shaky Ground by Elizabeth Douglass, InsideClimate News, July 20, 2015


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The importance of good climate communication: a recent Arctic example

Posted on 23 July 2015 by John Mason

Here's the abstract of a new paper in Nature Geoscience on Arctic sea-ice volume:

Changes in Arctic sea ice volume affect regional heat and freshwater budgets and patterns of atmospheric circulation at lower latitudes. Despite a well-documented decline in summer Arctic sea ice extent by about 40% since the late 1970s, it has been difficult to quantify trends in sea ice volume because detailed thickness observations have been lacking. Here we present an assessment of the changes in Northern Hemisphere sea ice thickness and volume using five years of CryoSat-2 measurements. Between autumn 2010 and 2012, there was a 14% reduction in Arctic sea ice volume, in keeping with the long-term decline in extent. However, we observe 33% and 25% more ice in autumn 2013 and 2014, respectively, relative to the 2010–2012 seasonal mean, which offset earlier losses. This increase was caused by the retention of thick sea ice northwest of Greenland during 2013 which, in turn, was associated with a 5% drop in the number of days on which melting occurred—conditions more typical of the late 1990s. In contrast, springtime Arctic sea ice volume has remained stable. The sharp increase in sea ice volume after just one cool summer suggests that Arctic sea ice may be more resilient than has been previously considered.

OK, let's pick this apart. Arctic sea-ice volume is the trickiest of the sea-ice variables to measure. Extent and area are by contrast straightforward. Volume depends on the survival of multi-year ice in any melt season. A pronounced melt season, like 2012, sees some of the multi-year ice lost. But if any of the ice that didn't melt in 2012 makes it through the 2013 season, you are going to get a volume increase. The authors state that they observed 33% more ice volume in autumn 2013 relative to the 2010-2012 mean. They go on to state that in 2014 there was 25% more ice volume relative to 2010-2012 – in other words it dropped again. That shows up on the following ice thickness distribution plot: the thickest ice is in red. Big red blob for 2013, much smaller one for 2014.

ice thickness map

Such observations are reasonably consistent with PIOMAS:

arctic sea ice volume - PIOMAS

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