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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.

Dana has been researching climate science, economics, and solutions since 2006, and has contributed to Skeptical Science since September, 2010.  He also blogs at The Guardian, and is the author of Climatology versus Pseudoscience.  He has published climate-related papers on various subjects, from the build-up of heat in the Earth's climate system to the expert consensus on human-caused global warming.

Follow 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

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.
Abraham, J., Cook, J., Fasullo, J., Jacobs, P., Mandia, S., & Nuccitelli, D. (2014). Review of the consensus and asymmetric quality of research on human-induced climate changeCosmopolis2014(1), 3-18.

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., 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

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.



Global warming deniers are an endangered species

Posted on 22 July 2015 by dana1981 &

At the end of this year there will be a critically important international climate change conference in Paris. At this conference, nations will attempt to reach an agreement to reduce greenhouse gas emissions and slow global warming.

Over the past few months there’s been a flood of big climate-related news, most of which will help build support and pressure for a strong agreement to curb global warming at the Paris conference. The political and social climate is shifting, and those in denial about human-caused climate change are struggling to adapt.

Scientific research underscores climate risks

John Abraham recently reported on two separate studies published in Nature andNature Climate Change, both of which found that global warming is intensifying several types of extreme weather. California is in the midst of a drought unprecedented in over a millennium, a heat wave is killing thousands of people in India and Pakistan, another has been baking Europe, and it seems as though half of North America is on fire.



No, the sun isn't going to save us from global warming

Posted on 16 July 2015 by dana1981 &

Some zombie myths just won’t die. In fact, I debunked this one two years ago at The Guardian

To sum up, a number of scientific studies have asked the question, ‘if the sun were to enter another extended quiet phase (a grand solar minimum), how would that impact global surface temperatures?’. Every study agrees, it would cause no more than 0.3°C cooling, which would only be enough to temporarily offset about a decade’s worth of human-caused global warming.


The global mean temperature difference is shown for the time period 1900 to 2100 for the IPCC A2 emissions scenario. The red line shows predicted temperature change for the current level of solar activity, the blue line shows predicted temperature change for solar activity at the much lower level of the Maunder Minimum, and the black line shows observed temperatures through 2010. Adapted from Feulner & Rahmstorf (2010).

Denial101x lecture debunking the ‘impending mini ice age’ myth by Dana Nuccitelli 

Solar activity is actually quite stable. That’s a good thing for us on Earth, because without big swings in the amount of energy reaching the planet from the sun, our climate is likewise generally quite stable. That’s allowed us to build big immobile cities and farms, with the confidence that the climate and weather will be pretty consistent in those areas. It’s allowed human civilization to develop over the past 10,000 years. Though with human-caused global warming in the process of destabilizing the climate, we’re putting that civilization under serious stress.



Climate denial linked to conspiratorial thinking in new study

Posted on 8 July 2015 by dana1981 &

A new study has examined the comments on climate science-denying blogs and found strong evidence of widespread conspiratorial thinking. The study looks at the comments made in response to a previous paper linking science denial and conspiracy theories.

Motivated rejection of science

Three years ago, social scientists Lewandowsky, Oberauer, and Gignac published a paper in the journal Psychological Science titled NASA Faked the Moon Landing—Therefore, (Climate) Science Is a Hoax: An Anatomy of the Motivated Rejection of Science

The paper detailed the evidence the scientists found that, using survey data provided by visitors to climate blogs, those exhibiting conspiratorial thinking are more likely to be skeptical of scientists’ conclusions about vaccinations, genetically modified foods, and climate change. This result was replicated in a follow-up study using a representative U.S. sample that obtained the same resultlinking conspiratorial thinking to climate denial.

Of course science denial and conspiracies go hand in hand

This shouldn’t be a terribly shocking result. When confronted with inconvenient science, those in denial often reject the evidence by accusing the experts of fraud or conspiracies. We saw a perfect example of this behavior just a few weeks ago. When scientists at NOAA published a paper finding that there was no ‘pause’ in global warming, one of the most common responses from those in denial involved the conspiratorial accusation that the scientists had somehow fudged the data at the behest of the Obama administration.



New study warns of dangerous climate change risks to the Earth’s oceans

Posted on 2 July 2015 by dana1981 &

A new paper just published in Science summarizes the projected impacts of climate change on the world’s oceans, and consequently on humans and our economy. The study concludes that global warming beyond the international limit of 2°C above pre-industrial temperatures would pose serious threats to marine ecosystems and their millions of human dependents. It builds on the consensus science published by the Intergovernmental Panel on Climate Change last year. The study concludes,

Ocean changes associated with a 2°C warming of global surface temperature carries high risks of impacts and should not be exceeded.


Regional changes in the physical system and associated risks for natural and human-managed systems. Source: Science; Gattuso et al. (2015) modified from IPCC WGII AR5 (2014).



Video: scientists simulate the climate of The Hobbit's Middle Earth

Posted on 17 June 2015 by dana1981 &

Dan Lunt is a climate scientist at the University of Bristol, and also a tremendous fan of J. R. R. Tolkien’s books. He was able to stitch together enough information to create a model of the fictional world of Middle Earth and simulate its climate.

As part of the Denial101x course, John Cook interviewed Lunt and discussed the process of simulating the climate of Middle Earth. The interview revealed some interesting tidbits. For example, as discussed in Part 2 below, parts of New Zealand, near where the movie was filmed, have a similar climate to that of The Shire. Los Angeles and Alice Springs, Australia share a climate similar to that of Mordor.

 The climate of Middle Earth interview, Part 1.

 The climate of Middle Earth interview, Part 2.

 The climate of Middle Earth interview, Part 3.

I also inquired whether Lunt might consider simulating the climate in the fictional world of Game of Thrones. 



What you need to know about the NOAA global warming faux pause paper

Posted on 8 June 2015 by dana1981 &

Last week, a paper out of NOAA concluded that contrary to the popular myth, there’s been no pause in global warming. The study made headlines across the world, including widely-read Guardian stories by John Abraham and Karl Mathiesen. In fact, there may have been information overload associated with the paper, but the key points are relatively straightforward and important.

1. Rapid Global Warming Continues

Arguments about short-term temperature changes only deal with the Earth’s surface temperatures, which account for just 1–2% of the overall warming of the planet. More than 90% of that heat goes into the oceans, and as my colleagues and I noted in a paper published 3 years ago, if anything that warming is accelerating, building up heat at a rate faster than 4 atomic bomb detonations per second.

If you carefully cherry pick start and end dates, you can find a period around 1998–2012 during which the warming of surface temperatures slowed a bit due to temporary natural cooling factors (like more La Niñas), just like it sped up a bit during the 1990s due to temporary natural warming factors (like more El Niños). But these are just wiggles on top of the long-term human-caused global warming trend. As Michael Mann put it,

there never was any “pause” or “hiatus” in global warming. There is evidence, however, for a modest, temporary slowdown in surface warming through the early part of this decade.

2. The Surface Warming Slowdown is Probably Over

This is a tough pill to swallow for those who have misused the short-term slowdown in global surface warming to argue against climate policies, but it’s likely over. 2014 was the hottest year on record, and 2015 looks likely to break the record again.



Research downplaying impending global warming is overturned

Posted on 3 June 2015 by dana1981 &

A new paper just published in Science Bulletin by Mark RichardsonZeke HausfatherDana NuccitelliKen Rice, and John Abraham shows that mainstream climate models simulate global temperature observations much better than the “irreducibly simple climate model” of Christopher MoncktonWillie SoonDavid Legates, and William Briggs.

When the Monckton paper was published in the Chinese journal Science Bulletinthis January, it was covered by conservative media outlets like the Daily Mail,Breitbart and World Net Daily, which used it to manufacture doubt about the dangers associated with human-caused global warming. The ideologically-appealing but scientifically incorrect message from the paper was essentially, ‘climate models are running hot, the climate is insensitive to the increasing greenhouse effect, and thus future global warming will be minimal and nothing to worry about.’

However, our team identified numerous glaring fundamental errors in the Monckton paper. The first was in the very premise of the paper itself, claiming that global climate models are “running hot.” In reality, as I show in my bookClimatology versus Pseudoscience, mainstream climate models have done a good job at projecting the observed changes in the global surface temperature.

While temperature measurements have been toward the lower of the range of model projections in recent years, there’s been a tremendous body of scientific research investigating the various contributors to the slowdown in global surface warming. This research, which was entirely ignored by Monckton and his colleagues, is summarized by Kevin Cowtan in week 5 of the Denial101x course.

 Kevin Cowtan’s Denial101x lecture



Memo to Jeb Bush: denying human-caused global warming is ignorant

Posted on 27 May 2015 by dana1981 &

In a campaign event last week, Republican presidential frontrunner Jeb Bush exhibited Stage 2 climate denial, saying (video available here),

Look, first of all, the climate is changing. I don’t think the science is clear what percentage is man-made and what percentage is natural. It’s convoluted. And for the people to say the science is decided on, this is just really arrogant, to be honest with you. It’s this intellectual arrogance that now you can’t even have a conversation about it.

The Politics

Unfortunately, denial of human-caused global warming may be a prerequisite for any viable Republican presidential candidate. Conservative and Tea Party Republicans are the one group of American voters among whom Stage 2 climate denial is the majority position, but they’re also the group that most reliably votes in GOP primary elections. 

In American politics, a candidate first has to win a primary election before reaching the national ballot. For Republicans, that means appealing to conservatives. It’s not clear that a Republican presidential candidate can accept climate science and run a viable primary campaign.

The Science

Nevertheless, the scientific evidence supporting human-caused global warming is just as strong as the evidence linking smoking and lung cancer. Last year, the IPCC stated with 95% confidence that humans are the main cause of the global warming that’s occurred since 1950. Their best estimate is that we’re responsible for about 100% of the warming during the past six decades.

Gavin Schmidt, Director of the NASA Goddard Institute for Space Studies, put together this graph showing what’s known as the probability density function of the human contribution to global warming since 1950, based on the IPCC report.


The probability density function for the fraction of warming attributable to human activity (derived from Fig. 10.5 in IPCC AR5). The bulk of the probability is far to the right of the “50%” line, and the peak is around 110%. Created by Gavin Schmidt.



Congress manufactures doubt and denial in climate change hearing

Posted on 21 May 2015 by dana1981 &

US Congress periodically holds hearings on issues related to climate change. Because the subject has become a partisan one in America, they generally follow a predictable pattern – Democrats invite science and policy expert witnesses who agree with the expert consensus on human-caused global warming and the need to address it, and Republicans invite witnesses who disagree.

John Christy at the University of Alabama at Huntsville is one of the fewer than 3% of climate scientists who publishes research suggesting that humans aren’t the primary cause of the current global warming. He’s thus become one of Republicans’ favorite expert witnesses.

Last week, the Committee on Natural Resources held a hearing to discuss draft guidance by the the President’s Council on Environmental Quality to include carbon pollution and the effects of climate change in the consideration of environmental impacts of federal projects, as part of the National Environmental Policy Act (NEPA) review process. Needless to say, the Republicans on the committee don’t like the idea, as is clear from the hearing highlights and lowlights in the video below.

 Highlights and lowlights from the May 13, 2015 Committee on Natural Resources NEPA hearing.

Christy Manufactures Doubt on Model Accuracy

Given that the hearing was ostensibly about environmental policy, most of the witnesses were policy experts. John Christy was the lone climate scientist invited to testify. His testimony focused on manufacturing doubt about the accuracy of climate models, climate change impacts, and about individual American projects’ contributions to global warming. On the accuracy of climate models, Christy played rather fast and loose with the facts, saying in his written testimony (emphasis added),



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