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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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dana1981

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.

Publications

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


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.

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17 comments


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

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12 comments


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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3 comments


Global warming denial rears its ugly head around the world, in English

Posted on 18 August 2014 by dana1981 &

As people’s understanding of climate science grows, among both experts and non-experts alike, we become more accepting of the fact that humans are the driving force behind global warming. That’s because the evidence supporting human-caused global warming is overwhelming; hence rejection of that reality is usually based on an incomplete understanding of the scientific evidence.

In Australia, Prime Minister Tony Abbott’s chief business adviser Maurice Newman offered a prime example of global warming denial last week. Writing in The Australian, Newman suggested that we’re headed for a period of global cooling due to declining solar activity and related influences from galactic cosmic rays, calling mainstream climate science “a religion.”

As Graham Readfearn showed in his fact check of The Australian opinion piece, Newman got the science badly wrong in almost every way imaginable. Scientific research has consistently shown that a grand solar minimum would barely make a dent in human-caused global warming, and that galactic cosmic rays do not exert a significant influence on the Earth’s climate. To argue otherwise, Newman relied on selective cherry picking of some research, and a misinterpretation of other studies.

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38 comments


New study finds fringe global warming contrarians get disproportionate media attention

Posted on 12 August 2014 by dana1981 &

A new study led by Bart Verheggen surveyed 1,868 scientists studying various aspects of climate change, asking them several questions mainly focused on what’s causing global warming. They survey also asked the respondents,

How frequently have you featured in the media regarding your views on climate change?

The answers to this question reflect whether the media is really fair and balanced on the subject of global warming. A truly balanced media would give equally proportional attention and coverage to climate scientists in the mainstream and on the fringes. For example, if 20% of contrarian climate scientists reported frequent media attention, a fair and balanced media would also give frequent coverage to 20% of mainstream climate scientists.

Instead, fringe contrarian climate scientists reported that they receive frequent media coverage twice as often as mainstream climate scientists.

Self-reported frequency of media coverage for respondents in different categories, segregated by their answer regarding the qualitative contribution of greenhouse gases to global warming. Self-reported frequency of media coverage for respondents in different categories, segregated by their answer regarding the qualitative contribution of greenhouse gases to global warming. Source: Environmental Science & Technology (Verheggen et al. 2014)

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8 comments


Facts can convince conservatives about global warming – sometimes

Posted on 7 August 2014 by dana1981 &

While there’s a 97% consensus among climate science experts and their research that humans are causing climate change, only about 67% of Americans believe global warming is even happening, including 25% of Tea Party members and 61% of other Republicans. Only about half of Americans realize that humans are causing global warming.

Social scientists have been investigating this disconnect between the evidence and expert consensus, and public opinion. Is it caused by information deficit and misinformation surplus, political and ideological biases, or some combination of these factors?

There’s one school of thought among social scientists that information just doesn’t matter – in fact, it might even be polarizing. In essence, liberals feel as though they’re on Team ‘global warming is a problem caused by humans’ while conservatives identify with Team ‘no it’s not.’ Some social scientists believe this cultural identity is so strong that scientific evidence, facts, and information can’t break through it. A 2012 study led by Yale’s Dan Kahan seemed to support this idea, finding that conservatives who are more scientifically literate are less worried about global warming.

However, that study looked at general science literacy. A new paper led by Sophie Guy, published in the European Journal of Social Psychology, looks at climate-specific knowledge and ideology. The authors conducted a survey of a national sample of 335 Australians and tested their climate knowledge by asking them to correctly identify factors that are and aren’t causing the rise in atmospheric greenhouse gases (for example, deforestation, automobiles, pesticides, and ozone depletion). They also asked participants, “How much do you feel you know about climate change?,” about their climate-related beliefs, and their ideology. The authors concluded,

...[climate] knowledge dampened the negative influence of individualist ideology on belief in climate change.

Individualists favor small government and self-sufficiency, in line with the libertarian wing of the Republican Party. Individualists were less likely than communitarians (those who think interdependence is an important part of society, i.e. “it takes a village”) to believe that climate change is happening. However, individualists with high climate-specific knowledge were significantly more likely to accept the climate is changing than those with low climate knowledge.

Interaction between specific knowledge and individualism on belief that climate change is occurring. Interaction between specific knowledge and individualism on belief that climate change is occurring. Photograph: European Journal of Social Psychology, Guy et al. (2014)

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19 comments


Sen Whitehouse Schools Sen Inhofe about Global Warming on the Senate Floor

Posted on 31 July 2014 by dana1981 &

Senator Sheldon Whitehouse (D-RI) throws down an epic schooling of Senator James Inhofe (R-OK) on global warming after Inhofe blocked a resolution from Senator Amy Klobuchar (D-MN) simply acknowledging that global warming exists and poses a threat to the interests of the United States.  Whitehouse makes several points that seem to originate from Skeptical Science, like The Escalator steps.  Well worth taking 7 minutes to watch - hat tip to Phil Plait at Bad Astronomy.

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13 comments


Nigel Lawson suggests he's not a skeptic, proceeds to deny global warming

Posted on 28 July 2014 by dana1981 &

Nigel Lawson is the chairman of the Global Warming Policy Foundation; a political group that regularly releases selective scientific reports about climate change. The organization consistently tries to argue that concerns about global warming – concerns that are based on the full body of scientific evidence – are overblown, which would imply that there's less urgency to solve the climate problem.

In a recent interview with The Independent, Lawson implied that he doesn't consider himself "a climate-change sceptic," but immediately proceeded to deny that the planet is warming, and reject mainstream scientific estimates of the climate sensitivity to the increased greenhouse effect.

There is no global warming to speak of going on at the moment. If you look at the Met Office statistics, that's quite clear. But there could be, there clearly could. If it does happen, there would be a much slower process than the alarmists pretend.

The first statement is untrue on several levels. First, even the Met Office HadCRUT4 estimates of global surface temperatures show we're still in the midst of a warming trend (you can easily check the data for yourself with this tool). Second, the Met Office estimates have a known cool bias due to a lack of coverage in the Arctic, and estimates correcting for that bias show an even larger surface warming trend.

Third and most importantly, the atmosphere only accounts for about 2% of the warming of the planet as a whole. Over 90% of global warming goes into heating the oceans. Studies that account for the warming of the entire global climate have found that it continues unabated. In fact, the planet has built up heat at a rate equivalent to 4 Hiroshima atomic bomb detonations per second over the past 15 years.

Land, atmosphere, and ice heating (red), 0-700 meter ocean heat content (OHC) increase (light blue), 700-2,000 meter OHC increase (dark blue).  From Nuccitelli et al. (2012) Land, atmosphere, and ice heating (red), 0-700 meter ocean heat content (OHC) increase (light blue), 700-2,000 meter OHC increase (dark blue). From Nuccitelli et al. (2012)

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21 comments


Climate models accurately predicted global warming when reflecting natural ocean cycles

Posted on 21 July 2014 by dana1981 &

Predicting global surface temperature changes in the short-term is a challenge for climate models. Temperature changes over periods of a decade or two can be dominated by influences from ocean cycles like El Niño and La Niña. During El Niño phases, the oceans absorb less heat, leaving more to warm the atmosphere, and the opposite is true during a La Niña.

We can't yet predict ahead of time how these cycles will change. The good news is that it doesn't matter from a big picture climate perspective, because over the long-term, temperature influences from El Niño and La Niña events cancel each other out. However, when we examine how climate model projections have performed over the past 15 years or so, those natural cycles make a big difference.

A new paper led by James Risbey just out in Nature Climate Change takes a clever approach to evaluating how accurate climate model temperature predictions have been while getting around the noise caused by natural cycles. The authors used a large set of simulations from 18 different climate models (from CMIP5). They looked at each 15-year period since the 1950s, and compared how accurately each model simulation had represented El Niño and La Niña conditions during those 15 years, using the trends in what's known as the Niño3.4 index.

Each individual climate model run has a random representation of these natural ocean cycles, so for every 15-year period, some of those simulations will have accurately represented the actual El Niño conditions just by chance. The study authors compared the simulations that were correctly synchronized with the ocean cycles (blue data in the left frame below) and the most out-of-sync (grey data in the right frame) to the observed global surface temperature changes (red) for each 15-year period.

The red dots on the thin red line correspond to the 15-year observed trends for each 15-year period.  The blue dots show the 15-year average trends from only those CMIP5 runs in each 15-year period where the model Niño3.4 trend is close to the observed Niño3.4 trend. The grey dots show the average 15-year trends for only the models with the worst correspondence to the observed Niño3.4 trend.  The size of the dots are proportional to the number of models selected.  The envelopes represent 2.5–97.5 percentile loess-smoothed fits to the models and data. Red: 15-year observed trends for each period. Blue: 15-year average trends from CMIP5 runs where the model Niño3.4 trend is close to observations. Grey: average 15-year trends for only the models with the worst correspondence to the Niño3.4 trend. The sizes of the dots are proportional to the number of models selected. From Nature Climate Change

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68 comments


Rupert Murdoch doesn't understand climate change basics, and that's a problem

Posted on 14 July 2014 by dana1981 &

Rupert Murdoch has a vast media empire. In the UK, his News Corp assets include The Times and The Sun. In the USA, he has Fox News, The New York Post, and The Wall Street Journal. In Australia, he's got The Australian and a multitude of local newspapers.

Many of Murdoch's news outlets are also among the worst when it comes to getting climate science wrong and disseminating climate myths and misinformation. Inaccurate media coverage is in turn the primary reason why the public is so misinformed about global warming.

In a recent Sky News interview, Rupert Murdoch expressed his own views about global warming and climate change.

Murdoch's most inaccurate statement was,

In terms of the world's temperature going up, the worst, the most alarmist things have said ... 3°C in 100 years. At the very most one of those will come from man-made, be man-made.

In reality, the worst case scenario considered by the 2014 IPCC report projects about 4°C global surface warming over the next century (on top of the nearly 1°C that we've already caused). All of that 4°C warming would be human-caused. The best case scenario would involve about 1°C global surface warming over the next century, and that's if we take serious action to reduce carbon pollution.

IPCC AR5 projected global average surface temperature changes in a high emissions scenario (RCP8.5; red) and low emissions scenario (RCP2.6; blue). IPCC AR5 projected global average surface temperature changes in a high emissions scenario (RCP8.5; red) and low emissions scenario (RCP2.6; blue).

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43 comments



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