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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Dana Nuccitelli is an environmental scientist at a private environmental consulting firm in the Sacramento, California area. He has a Bachelor's Degree in astrophysics from the University of California at Berkeley, and a Master's Degree in physics from the University of California at Davis. He has been researching climate science, economics, and solutions as a hobby since 2006, and has contributed to Skeptical Science since September, 2010.  He also blogs at The GuardianFollow him on Twitter.


Nuccitelli, D., Way, R., Painting, R., Church, J., & Cook, J. (2012). Comment on ocean heat content and Earth's radiation imbalance. II. Relation to climate shifts. Physics Letters A.

Cook, J., Nuccitelli, D., Green, S.A., Richardson, M., Winkler, B., Painting, R., Way, R., Jacobs, P., & Skuce, A. (2013). Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters, 8(2), 024024+.

Cook, J., Nuccitelli, D., Skuce, A., Way, R., Jacobs, P., Painting, R., Honeycutt, R., Green, S.A. (2014). Reply to Comment on ‘Quantifying the consensus on anthropogenic global warming in the scientific literature: a Reanalysis’. Energy Policy. DOI: 10.1016/j.enpol.2014.06.002

Benestad, R. E., Hygen, H. O., Dorland, R. V., Cook, J., & Nuccitelli, D. (2013). Agnotology: learning from mistakes. Earth System Dynamics Discussions, 4(1), 451-505.

Nuccitelli, D. A., Abraham, J. P., Benestad, R. E., & Mandia, S. A. (2013). Comment on: Akasofu, S.-I. On the Present Halting of Global Warming. Climate 2013, 1, 4–11. Climate, 1(2), 76-83.

Nuccitelli, D., Richter, M. J., & McCall, B. J. (2005). A search for interstellar carbon-60. In IAU Symposium (Vol. 235, p. 236P).

Encrenaz, T., Bézard, B., Greathouse, T., Holmes, S., Richter, M., Nuccitelli, D., & Forget, F. et al. (2006, February). Ground-based high-resolution IR spectroscopy of Mars: H2O and H2O2 mapping, search for CH4, and determination of CO2 isotopic ratios. In Second Workshop on Mars Atmosphere Modelling and Observations, held February.


Recent blog posts

Republican politicians aren't climate scientists or responsible leaders

Posted on 28 October 2014 by dana1981 &

Republican Senate Minority Leader Mitch McConnell is hoping to become the Senate Majority Leader after the forthcoming election on November 4th, although despite hailing from conservative Kentucky, McConnell is in a very tight race. The Cincinnati Enquirer editorial board recently had a long discussion with McConnell and tried to pin him down on the subject of global warming.

McConnell wouldn’t directly answer whether he believes in climate change.

Enquirer’s editorial board volleyed several questions about what it would take to convince him of climate change. He turned the subject every time to jobs. McConnell said he believes imposing regulations to reduce greenhouse gases blamed for climate change would only hurt America and not mitigate what other countries, such as China, are doing...

“We can debate this forever,” McConnell said. “George Will had a column in the last year or so pointing out that in the 70s, we were concerned the ice age was coming. I’m not a scientist. I’m interested in protecting Kentucky’s economy.”

Leaving aside McConnell’s reference to the 1970s ice age myth, the cop-out about not being a scientist is a strange and dangerous one.



2014 Arctic sea ice extent - 6th lowest in millennia

Posted on 23 October 2014 by dana1981 &

The National Snow and Ice Data Center has reported that this year we saw the 6th-lowest minimum Arctic sea ice extent on record. Research has shown that most of the long-term decline in sea ice, or the “death spiral” as it’s come to be known, is due to human-caused global warming.

Natural factors play a role in the extent of the Arctic sea ice as well, especially changes in weather conditions on a year-to-year basis. For example, 2012 shattered the previous record low Arctic sea ice extent because on top of the human influences, the weather conditions were ripe for a dramatic decline that year. In 2013 and 2014, weather conditions were closer to normal, so they didn’t break the 2012 record. As a result, the usual suspects have declared that Arctic sea ice is now “expanded” compared to 2 years ago.

The flaw in that argument is illustrated in this animated graphic I created.

sea ice escalator

September Arctic sea ice extent data since 1980 from the National Snow and Ice Data Center (blue diamonds).  "Recovery" years, meaning years when the sea ice extent is greater than the previous year, are highlighted in red to mock the repeated cynical claims of climate change "skeptics" that global warming has somehow stopped.



Dinner with global warming contrarians, disaster for dessert

Posted on 13 October 2014 by dana1981 &

Twelve climate scientists and contrarians recently had dinner together in the UK, which for some reason received media attention. While everyone should be free to have dinner with whomever they like, the problem with this particular event was that the ensuing media coverage made the contrarians seem downright reasonable. For example, the article about the dinner stated,

“...the insults slung around online only hinder the process of rational scientific debate.”

Yet one of the contrarians attending the dinner was Anthony Watts, who runs a blog that regularly insults climate scientists and climate realists. In fact, just a few days after the dinner, Watts was already taunting Ben Santer, one of the world’s most highly respected climate scientists, who had previously treated Watts with courtesy and respect. The article also quoted Watts as saying,

We’ve been at odds so long, it is time to present science together,

Climate contrarians are already free to present science at climate conferences. For example, the annual American Geophysical Union (AGU) fall meeting is the largest gathering of climate scientists presenting and discussing their research. Every year, the vast majority of scientific research presented at the AGU conference and others like it (about 97% or so) is consistent with the expert consensus on human-caused global warming. Contrarians don’t present science there because they have so little science to present.

The Mail on Sunday’s David Rose also attended the dinner. His latest climate article focused on the slight increase in Arctic sea ice as compared to the record low of two years ago (and of course on Al Gore), while ignoring the fact that the Arctic has lost about 70% of its total volume of sea ice over the past three decades.



GWPF funder Lord Leach – relying on unreliable sources of global warming information

Posted on 8 October 2014 by dana1981 &

DeSmog UK has found that libertarian banker Lord Leach is a likely funder of the anti-climate political advocacy group Global Warming Policy Foundation (GWPF). In May of 2009, Lord Leach gave a long speech in Parliament detailing his beliefs about global warming.

The speech was full of inaccuracies, myths, and misinformation. Known as a Gish Gallop, the sheer number of false claims in the speech would require tremendous effort to debunk. Most telling were the sources that Lord Leach relied upon to support his statements. For example,

Probably the best climatologist in the world is Professor Lindzen and another good one is Professor Singer.

While Richard Lindzen is a climate scientist, he’s also the climate scientist who’s been the wrongest, longest. Throughout his climate science career, Lindzen consistently took positions that were contrary to the climate science mainstream. For example, Lindzen claimed that global warming over the 20th century was minimal, that humans have an insignificant impact on global temperatures, and that water vapor will act to dampen global warming. All of these claims and many more have proven to be completely wrong. In another contrarian position, Lindzen has disputed the link between secondhand smoke and lung cancer.



Global warming: a battle for evangelical Christian hearts and minds

Posted on 2 October 2014 by dana1981 &

The Cornwall Alliance for the Stewardship of Creation is a conservative evangelical Christian public policy group that promotes a free-market approach to protecting the environment. The organization recently published a list of ten reasons it opposes policies to reduce carbon pollution and slow global warming, purportedly to protect the poor. As the first point on the list illustrates, the group essentially believes that the Earth’s climate will be able to correct any damage done by humans.

1. As the product of infinitely wise design, omnipotent creation, and faithful sustaining (Genesis 1:1–31; 8:21–22), Earth is robust, resilient, self-regulating, and self-correcting.

The group includes climate scientist Roy Spencer and professor of geography David Legates. Spencer’s research is among the 2–3% of peer-reviewed climate papers disputing that humans are the main cause of global warming. He has often argued that climate policies will harm the poor, and has not been shy in making political and free market statements, having gone as far as to make comments about “global warming Nazis.” Legates is known for disputing the 97% expert consensus on human-caused global warming.

The Cornwall Alliance has tried to use scientific arguments to support its religious beliefs about the resiliency of the global climate, claiming,

3. While human addition of greenhouse gases, particularly carbon dioxide (CO2), to the atmosphere may slightly raise atmospheric temperatures, observational studies indicate that the climate system responds more in ways that suppress than in ways that amplify CO2’s effect on temperature, implying a relatively small and benign rather than large and dangerous warming effect.



The Wall Street Journal downplays global warming risks once again

Posted on 22 September 2014 by dana1981 &

As has become the norm for media outlets owned by Rupert Murdoch, just before a half million people participated in the People’s Climate March around the world, The Wall Street Journal published an opinion piece downplaying the risks and threats posed by human-caused global warming. The editorial was written by Steven Koonin, a respected computational physicist who claims to have engaged in “Detailed technical discussions during the past year with leading climate scientists,” but who is himself not a climate scientist.

Koonin did admit that the climate is changing and humans are largely responsible, and noted,

There is well-justified prudence in accelerating the development of low-emissions technologies and in cost-effective energy-efficiency measures.

This is a step in the right direction. Unfortunately, Koonin’s editorial focused almost exclusively on the remaining uncertainties in climate science. Ironically, he stated,



50 Canadian climate researchers speak out in support of the People's Climate March

Posted on 20 September 2014 by dana1981 &

The Canadian government is hell-bent on exploiting the Alberta tar sands to the fullest extent possible, even at the expense of the global climate. Canada simply cannot meet its carbon pollution reduction pledges if it continues to expand tar sands operations.

While the American government has finally begun to take the threat of climate change seriously and do something about it, the Canadian government has merely played lip service to the problem. 50 Canadian climate researchers have reached the point where they feel the need to speak out, using the People’s Climate March on September 21st as a catalyst to call for action. To that end, they penned the following letter.



The 97% v the 3% – just how much global warming are humans causing?

Posted on 15 September 2014 by dana1981 &

A pair of climate scientists recently had a dispute regarding how much global warming humans are responsible for. Gavin Schmidt from Nasa represented the consensus of 96–97% of climate experts in arguing that humans have been the dominant cause of global warming since 1950, while Judith Curry from Georgia Tech represented the opinions of 2–4% of climate experts that we could be responsible for less than half of that warming.

Curry is to be the featured speaker on this subject at a National Press Club event tomorrow hosted by the Marshall Institute; a right-wing thinktank that has spread misinformation about the dangers of smoking, ozone depletion, acid rain, DDT, and now climate change. She may also discuss the subject at an event next week hosted by the fossil fuel-funded right-wing think tank Texas Public Policy Foundation (TPPF).

The exchange between Schmidt and Curry can be read on RealClimate – a blog run by climate scientists. The discrepancy in both the quantity and quality of the supporting evidence used by each scientist was one of the most telling aspects of their debate.

For his part, Schmidt referenced the most recent IPCC report. The IPCC summarises the latest and greatest climate science research, so there is no better single source. The figure below from the IPCC report illustrates why 96–97% of climate science experts and peer-reviewed research agree that humans are the main cause of global warming.

The black bar indicates the amount of global surface warming observed from 1951 to 2010. The green bar shows the amount of warming caused by human greenhouse gas emissions during that time. The yellow is the influence from other human effects (mainly cooling from human sulfate aerosol emissions, which scatter sunlight), and the orange is the combined human effect. Below those are the contributions from external natural factors (mainly the sun and volcanoes) and from natural internal variability (mainly ocean cycles), while the whiskers show the uncertainty range for each.

IPCC AR5 Figure 10.5: Assessed likely ranges (whiskers) and their mid-points (bars) for attributable warming trends over the 1951–2010 period due to well-mixed greenhouse gases, other anthropogenic forcings (OA), natural forcings (NAT), combined anthropogenic forcings (ANT) and internal variability. The HadCRUT4 observations are shown in black with the 5 to 95% uncertainty range due to observational uncertainty in this record. IPCC AR5 figure 10.5: Likely ranges (whiskers) and their mid-points (bars) for attributable warming trends over the 1951–2010 period due to greenhouse gases, other anthropogenic forcings (OA), natural forcings (NAT), combined anthropogenic forcings (ANT) and internal variability. The HadCRUT4 observations are shown in black.



Fire and water – how global warming is making weather more extreme and costing us money

Posted on 2 September 2014 by dana1981 &

Connecting the dots between human-caused global warming and specific extreme weather events has been a challenge for climate scientists, but recent research has made significant advances in this area. Links have been found between some very damaging extreme weather events and climate change.

For example, research has shown that a “dipole” has formed in the atmosphere over North America, with a high pressure ridge off the west coast, and a low pressure trough over the central and eastern portion of the continent.

Departure of the November 2013 – January 2014 250 hPa geopotential height from the normal climatology. Departure of the November 2013 – January 2014 250 hPa geopotential height from the normal climatology. Source: Wang et al. (2014), Geophysical Research Letters Photograph: Wang et al. (2014), Geophysical Research Letters

These sorts of pressure ridges in the atmosphere are linked to “waves” in the jet stream. Research has shown that when these jet stream waves form, they’re accompanied by more intense extreme weather. The high pressure zone off the west coast or North America has been termed the “Ridiculously Resilient Ridge” due to its persistence over the past two years. It’s been the main cause of California’s intense drought by pushing rain storms around the state.

California drought as of 26 August 2014.  58% of the state is in 'exceptional drought' conditions. California drought as of 26 August 2014. 58% of the state is in ‘exceptional drought’ conditions. Source: United States Drought Monitor



Unpacking unpaused global warming – climate models got it right

Posted on 25 August 2014 by dana1981 &

Although the global climate has continued to build up heat at an incredibly rapid rate, there has been a keen focus among climate contrarians and in the media on the slowdown of the warming at the Earth’s surface. The slowdown is in fact a double cherry pick – it focuses only on the 2% of global warming that heats the atmosphere (over 90% heats the oceans), and it only considers the past 10–15 years. Nevertheless, because there was so much attention paid to the surface warming slowdown, the latest IPCC report addressed it specifically, saying,

The long-term climate model simulations show a trend in global-mean surface temperature from 1951 to 2012 that agrees with the observed trend (very high confidence). There are, however, differences between simulated and observed trends over periods as short as 10 to 15 years (e.g., 1998 to 2012).

From 1998 through 2012, the Met Office estimated that global surface temperatures had warmed by about 0.06°C, whereas the average climate model projection put the value at closer to 0.3°C. This apparent discrepancy only represented a tiny fraction of overall global warming, and over a short enough period of time that the internal noise of the climate system could be having a significant influence, but it was nevertheless a challenge for climate scientists to explain the precise causes of the difference.



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