Blog Archive

Friday, February 12, 2016

Peter Sinclair video: Paris Climate Agreement - A Good Start

by Peter Sinclair, Yale Climate Communications, February 10, 2016

I was at the American Geophysical Union Fall Meeting in San Francisco when news of the Paris agreement came through, so had the chance to collect fresh reactions from some of the best climate experts on the planet.

Generally, hopeful reactions, mixed with a warning.  And, Jeff Goodell of Rolling Stone on the difference between “should” and “shall.”


John Abraham: The gutting of CSIRO climate change research is a big mistake

To be able to adapt to climate change, we need scientists to project how the climate will change

Australian Prime Minister Malcolm Turnbull arrives to announce his Innovation Statement at the Discovery Centre at the CSIRO in Canberra on Monday, Dec. 7, 2015.
Australian Prime Minister Malcolm Turnbull arrives to announce his Innovation [really?] Statement at the Discovery Centre at the CSIRO in Canberra on Monday, December 7, 2015. Photograph: Mick Tsikas/AAP

by John Abraham, "Climate Consensus - The 97%," The Guardian, February 10, 2016

Last week, surprise news shocked the world’s scientific community. One of the most prestigious and productive scientific organizations is slashing hundreds of jobs, many related to climate change research. The organization, the Commonwealth Scientific and Industrial Research Organization (CSIRO for short) is simply put, one of the best in the world. It rivals well-known groups like NASA, NOAA, and the Hadley Centre for its contributions to climate science.
What does CSIRO do that is so special? Many things. For instance, they are world leaders in measuring what is happening to the planet. Their research includes ocean-going vessels and other instrumentation that measure the chemistry and temperature of the ocean: they help track where human-emitted carbon dioxide is going, how heat is building up in the oceans, and what is happening with the general health of the ocean biosystem.
CSIRO is also a modeling superpower. Their climate models form the backbone of our understanding of what changes have happened and what changes will happen because of human greenhouse gases.
But they also have deepened our knowledge about extreme weather. They’ve provided insights regarding how droughts, heat waves, and floods will change in the future.
All of these contributions are important not only for the understanding that they provide but also because this knowledge helps us plan for the future. If you want to know what we can do to mitigate or adapt to climate change, you need this information.
But according to CSIRO chief executive, Larry Marshall, CSIRO should shift focus. Here is the key statement he made last week:

Our climate models are among the best in the world and our measurements honed those models to prove global climate change. That question has been answered, and the new question is what do we do about it, and how can we find solutions for the climate we will be living with?
Are you kidding me? What kind of backward logic is this? From the reports I’ve read, something like 350 positions will be cut from CSIRO with the heaviest cuts (over 100) coming from the climate research groups. How can you predict how to adapt if you don’t know what you are going to adapt to? This doesn’t make sense. 
Sure, I have colleagues at CSIRO (who I also consider friends). Sure I don’t want them to lose their jobs. But, the real reason this foolish move upsets me is that it forces decision-makers to fly with blinders on as they make decisions for our future. How fast will the planet warm? What will the impacts be? How will it change weather patterns? How will those weather patterns affect the Earth’s biological systems? All of these questions and more will be harder to answer after these cuts. 
Australia is a small country (by population). Yet, it has punched far above its weight class in research. To think that this treasure of a research organization will be gutted is just shocking.
This story has gotten a lot of press in Australia such as here and here. It is also covered in international venues such as here and petitions such as here and here. Let’s hope this move is reversed before it is too late. 

Thursday, February 4, 2016

India's rice revolution

In a village in India's poorest state, Bihar, farmers are growing world record amounts of rice – with no GM, and no herbicide. Is this one solution to world food shortages? 

Sumant Kumar
Sumant Kumar photographed in Darveshpura, Bihar, India. Photograph: Chiara Goia for Observer Food Monthly

by John Vidal, The Guardian, February 16, 2013

Sumant Kumar was overjoyed when he harvested his rice last year. There had been good rains in his village of Darveshpura in north-east India and he knew he could improve on the four or five tonnes per hectare that he usually managed. But every stalk he cut on his paddy field near the bank of the Sakri river seemed to weigh heavier than usual, every grain of rice was bigger and when his crop was weighed on the old village scales, even Kumar was shocked.

This was not six or even 10 or 20 tonnes. Kumar, a shy young farmer in Nalanda district of India's poorest state Bihar, had – using only farmyard manure and without any herbicides – grown an astonishing 22.4 tonnes of rice on one hectare of land. This was a world record and with rice the staple food of more than half the world's population of seven billion, big news.
It beat not just the 19.4 tonnes achieved by the "father of rice," the Chinese agricultural scientist Yuan Longping, but the World Bank-funded scientists at the International Rice Research Institute in the Philippines, and anything achieved by the biggest European and American seed and GM companies. And it was not just Sumant Kumar. Krishna, Nitish, Sanjay and Bijay, his friends and rivals in Darveshpura, all recorded over 17 tonnes, and many others in the villages around claimed to have more than doubled their usual yields.
The villagers, at the mercy of erratic weather and used to going without food in bad years, celebrated. But the Bihar state agricultural universities didn't believe them at first, while India's leading rice scientists muttered about freak results. The Nalanda farmers were accused of cheating. Only when the state's head of agriculture, a rice farmer himself, came to the village with his own men and personally verified Sumant's crop, was the record confirmed.
A tool used to harvest rice
A tool used to harvest rice. Photograph: Chiara Goia
The rhythm of Nalanda village life was shattered. Here bullocks still pull ploughs as they have always done, their dung is still dried on the walls of houses and used to cook food. Electricity has still not reached most people. Sumant became a local hero, mentioned in the Indian parliament and asked to attend conferences. The state's chief minister came to Darveshpura to congratulate him, and the village was rewarded with electric power, a bank and a new concrete bridge.
That might have been the end of the story had Sumant's friend Nitish not smashed the world record for growing potatoes six months later. Shortly after Ravindra Kumar, a small farmer from a nearby Bihari village, broke the Indian record for growing wheat. Darveshpura became known as India's "miracle village", Nalanda became famous and teams of scientists, development groups, farmers, civil servants and politicians all descended to discover its secret.
When I meet the young farmers, all in their early 30s, they still seem slightly dazed by their fame. They've become unlikely heroes in a state where nearly half the families live below the Indian poverty line and 93% of the 100 million population depend on growing rice and potatoes. Nitish Kumar speaks quietly of his success and says he is determined to improve on the record. "In previous years, farming has not been very profitable," he says. "Now I realise that it can be. My whole life has changed. I can send my children to school and spend more on health. My income has increased a lot."
What happened in Darveshpura has divided scientists and is exciting governments and development experts. Tests on the soil show it is particularly rich in silicon but the reason for the "super yields" is entirely down to a method of growing crops called System of Rice (or root) Intensification (SRI). It has dramatically increased yields with wheat, potatoes, sugar cane, yams, tomatoes, garlic, aubergine and many other crops and is being hailed as one of the most significant developments of the past 50 years for the world's 500 million small-scale farmers and the two billion people who depend on them.
People work on a rice field in Bihar
People work on a rice field in Bihar. Photograph: Chiara Goia
Instead of planting three-week-old rice seedlings in clumps of three or four in waterlogged fields, as rice farmers around the world traditionally do, the Darveshpura farmers carefully nurture only half as many seeds, and then transplant the young plants into fields, one by one, when much younger. Additionally, they space them at 25cm intervals in a grid pattern, keep the soil much drier and carefully weed around the plants to allow air to their roots. The premise that "less is more" was taught by Rajiv Kumar, a young Bihar state government extension worker who had been trained in turn by Anil Verma of a small Indian NGO called Pran (Preservation and
Proliferation of Rural Resources and Nature), which has introduced the SRI method to hundreds of villages in the past three years.
While the "green revolution" that averted Indian famine in the 1970s relied on improved crop varieties, expensive pesticides and chemical fertilisers, SRI appears to offer a long-term, sustainable future for no extra cost. With more than one in seven of the global population going hungry and demand for rice expected to outstrip supply within 20 years, it appears to offer real hope. Even a 30% increase in the yields of the world's small farmers would go a long way to alleviating poverty.
"Farmers use less seeds, less water and less chemicals but they get more without having to invest more. This is revolutionary," said Dr Surendra Chaurassa from Bihar's agriculture ministry. "I did not believe it to start with, but now I think it can potentially change the way everyone farms. I would want every state to promote it. If we get 30-40% increase in yields, that is more than enough to recommend it."
The results in Bihar have exceeded Chaurassa's hopes. Sudama Mahto, an agriculture officer in Nalanda, says a small investment in training a few hundred people to teach SRI methods has resulted in a 45% increase in the region's yields. Veerapandi Arumugam, the former agriculture minister of Tamil Nadu state, hailed the system as "revolutionising" farming.
SRI's origins go back to the 1980s in Madagascar where Henri de Laulanie, a French Jesuit priest and agronomist, observed how villagers grew rice in the uplands. He developed the method but it was an American, professor Norman Uphoff, director of the International Institute for Food, Agriculture and Development at Cornell University, who was largely responsible for spreading the word about De Laulanie's work.
Given $15m by an anonymous billionaire to research sustainable development, Uphoff went to Madagascar in 1983 and saw the success of SRI for himself: farmers whose previous yields averaged two tonnes per hectare were harvesting eight tonnes. In 1997 he started to actively promote SRI in Asia, where more than 600 million people are malnourished.
"It is a set of ideas, the absolute opposite to the first green revolution [of the 60s] which said that you had to change the genes and the soil nutrients to improve yields. That came at a tremendous ecological cost," says Uphoff. "Agriculture in the 21st century must be practised differently. Land and water resources are becoming scarcer, of poorer quality, or less reliable. Climatic conditions are in many places more adverse. SRI offers millions of disadvantaged households far better opportunities. Nobody is benefiting from this except the farmers; there are no patents, royalties or licensing fees."
Rice seeds
Rice seeds. Photograph: Chiara Goia
For 40 years now, says Uphoff, science has been obsessed with improving seeds and using artificial fertilisers: "It's been genes, genes, genes. There has never been talk of managing crops. Corporations say 'we will breed you a better plant' and breeders work hard to get 5-10% increase in yields. We have tried to make agriculture an industrial enterprise and have forgotten its biological roots."
Not everyone agrees. Some scientists complain there is not enough peer-reviewed evidence around SRI and that it is impossible to get such returns. "SRI is a set of management practices and nothing else, many of which have been known for a long time and are best recommended practice," says Achim Dobermann, deputy director for research at the International Rice Research Institute. "Scientifically speaking I don't believe there is any miracle. When people independently have evaluated SRI principles then the result has usually been quite different from what has been reported on farm evaluations conducted by NGOs and others who are promoting it. Most scientists have had difficulty replicating the observations."
Dominic Glover, a British researcher working with Wageningen University in the Netherlands, has spent years analysing the introduction of GM crops in developing countries. He is now following how SRI is being adopted in India and believes there has been a "turf war."
"There are experts in their fields defending their knowledge," he says. "But in many areas, growers have tried SRI methods and abandoned them. People are unwilling to investigate this. SRI is good for small farmers who rely on their own families for labour, but not necessarily for larger operations. Rather than any magical theory, it is good husbandry, skill and attention which results in the super yields. Clearly in certain circumstances, it is an efficient resource for farmers. But it is labour intensive and nobody has come up with the technology to transplant single seedlings yet."
But some larger farmers in Bihar say it is not labour intensive and can actually reduce time spent in fields. "When a farmer does SRI the first time, yes it is more labour intensive," says Santosh Kumar, who grows 15 hectares of rice and vegetables in Nalanda. "Then it gets easier and new innovations are taking place now."
In its early days, SRI was dismissed or vilified by donors and scientists but in the past few years it has gained credibility. Uphoff estimates there are now 4-5 million farmers using SRI worldwide, with governments in China, India, Indonesia, Cambodia, Sri Lanka and Vietnam promoting it.

Sumant, Nitish and as many as 100,000 other SRI farmers in Bihar are now preparing their next rice crop. It's back-breaking work transplanting the young rice shoots from the nursery beds to the paddy fields but buoyed by recognition and results, their confidence and optimism in the future is sky high.
Last month Nobel prize-winning economist Joseph Stiglitz visited Nalanda district and recognised the potential of this kind of organic farming, telling the villagers they were "better than scientists". "It was amazing to see their success in organic farming," said Stiglitz, who called for more research. "Agriculture scientists from across the world should visit and learn and be inspired by them."
A man winnows rice in Satgharwa village
A man winnows rice in Satgharwa village. Photograph: Chiara Goia
Bihar, from being India's poorest state, is now at the centre of what is being called a "new green grassroots revolution" with farming villages, research groups and NGOs all beginning to experiment with different crops using SRI. The state will invest $50m in SRI next year but western governments and foundations are holding back, preferring to invest in hi-tech research. The agronomist Anil Verma does not understand why: "The farmers know SRI works, but help is needed to train them. We know it works differently in different soils but the principles are solid," he says. "The biggest problem we have is that people want to do it but we do not have enough trainers.
"If any scientist or a company came up with a technology that almost guaranteed a 50% increase in yields at no extra cost they would get a Nobel prize. But when young Biharian farmers do that they get nothing. I only want to see the poor farmers have enough to eat."

Saturday, January 30, 2016

Climate Science Legal Defense Fund Celebrates its Four-Year Anniversary

by Jeff Masters, WunderBlog, January 28, 2016

Whenever scientific research uncovers truths that threaten the profits of large and powerful corporations, those companies--and the politicians these corporations' money help elect -- inevitably fight back by attacking the scientists. As I discussed in detail in my 2009 blog post, "The Manufactured Doubt Industry and the Hacked Email Controversy," we've seen this behavior most clearly with the tobacco industry, but manufacturers of chlorofluorocarbons, asbestos, benzene, beryllium, chromium, MTBE, perchlorates, phthalates, and a slew of many other toxic chemicals have all waged elaborate campaigns to attack the scientific findings and the scientists that threatened their profits. These attacks often take the form of legal action, which government or university-funded scientists do not have the resources to combat. Such attacks against climate scientists have been particularly pernicious and numerous in recent years, and multiple climate scientists are currently involved in litigation in state and federal courts across the United States. 

The Climate Science Legal Defense Fund (CSLDF) was created to help these climate scientists fight back. CSLDF works to help raise funds for scientists’ legal defenses, serves as a resource in finding pro bono legal representation, and provides support during difficult litigation proceedings as well as when legal action is threatened. I'm proud to say that I'm a founding board member of the charity, and this week marks the four-year anniversary of their official debut. Over that time, they’ve helped nearly a hundred researchers across the country, from Arizona to Virginia. 

In celebration of their birthday, they’ve launched a new website at The new site explains their history, details their initial work defending Dr. Michael Mann, and describes their current projects. I hope you will consider making a donation to this worthy cause in the future. 

Figure 1. Screen shot of the new website at

To learn more about the well-funded attacks on climate science and climate scientists by the fossil fuel industry, my fellow CSLDF board member, Noami Oreskes, has co-authored the excellent book, Merchants of Doubt, which has also been made into a fascinating documentary (available on Netflix.)

Sunday, January 17, 2016

Ben Santer & Carl Mears: A Response to Ted Cruz's “Data or Dogma?” hearing

by Benjamin D. Santer (Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, CA) and Carl Mears (Remote Sensing Systems, Santa Rosa, CA), Skeptical Science, January 17, 2016

[PDF available here:]

On December 8, 2015, Senator Ted Cruz – the chairman of the Senate subcommittee on Space, Science, and Competitiveness – convened a hearing entitled “Data or Dogma?” The stated purpose of this event was to promote “…open inquiry in the debate over the magnitude of human impact on Earth’s climate” (ref. 1). In the course of the hearing, the chairman and several expert witnesses claimed that satellite temperature data falsify both “apocalyptic models” and findings of human effects on climate by “alarmist” scientists. Such accusations are serious but baseless. The hearing was more political theatrics than a deep dive into climate science.  
Satellite-derived temperature data were a key item of evidence at the hearing. One of the witnesses [a] for the majority side of the Senate subcommittee showed the changes (over roughly the last 35 years) in satellite- and weather-balloon-based measurements of the temperature of the mid-troposphere (TMT), a layer of the atmosphere extending from the Earth’s surface to roughly 18 km (ref. 2). Satellite TMT measurements are available from late 1978 to present. Observed TMT data were compared with TMT estimates from a large number of model simulations. This comparison was ‘Exhibit A’ for the majority side of the subcommittee.
Senator Cruz used Exhibit A as the underpinning for the following chain of arguments: (1) Satellite TMT data do not show any significant warming over the last 18 years, and are more reliable than temperature measurements at Earth’s surface; (2) The apparent “pause” in tropospheric warming is independently corroborated by weather balloon temperatures; (3) Climate models show pronounced TMT increases over the “pause” period; and (4) The mismatch between modeled and observed tropospheric warming in the early 21st century has only one possible explanation – computer models are a factor of three too sensitive to human-caused changes in greenhouse gases (GHGs). Based on this chain of reasoning, Senator Cruz concluded that satellite data falsify all climate models, that the planet is not warming, and that humans do not impact climate.
This logic is wrong. First, satellites do not provide direct measurements of atmospheric temperature: they are not thermometers in space. The satellite TMT data plotted in Exhibit A were obtained from so-called Microwave Sounding Units (MSUs), which measure the microwave emissions of oxygen molecules from broad atmospheric layers (refs. 24)[b]. Converting this information to estimates of temperature trends has substantial uncertainties [c]. The major uncertainties arise because the satellite TMT record is based on measurements made by over 10 different satellites, most of which experience orbital decay (ref. 5) and orbital drift (refs. 68) over their lifetimes. These orbital changes affect the measurements of microwave emissions, primarily due to gradual shifts in the time of day at which measurements are made. As the scientific literature clearly documents, the adjustments for such shifts in measurement time are large [d], and involve many subjective decisions (refs. 24, 68). Further adjustments to the raw data are necessary for drifts in the on-board calibration of the microwave measurements (refs. 9, 10), and for the transition between earlier and more sophisticated versions of the MSU[e].
In navigating through this large labyrinth of necessary adjustments to the raw data, different plausible adjustment choices lead to a wide range of satellite TMT trends (refs. 210). This uncertainty has been extensively studied in the scientific literature, but was completely ignored in the discussion of Exhibit A by Senator Cruz and by witnesses for the majority side of the subcommittee (refs. 215). The majority side was also silent on the history of satellite temperature datasets. For example, there was no mention of the fact that one group’s analysis of satellite temperature data – an analysis indicating cooling of the global troposphere – was repeatedly found to be incorrect by other research groups (refs. 2, 3, 510).
Such corrective work is ongoing. Satellite estimates of atmospheric temperature change are still a work in progress (refs. 2, 3, 8), and the range of estimates produced by different groups remains large.[f] The same is true of weather balloon atmospheric temperature measurements (refs. 2, 1113, 1517)[g]. Surface thermometer records also have well-studied uncertainties (refs. 2, 19, 20), but the estimated surface warming of roughly 0.9 °C since 1880 has been independently confirmed by multiple research groups (refs. 2, 15, 19, 20).
The hearing also failed to do justice to the complex issue of how to interpret differences between observed and model-simulated tropospheric warming over the last 18 years. Senator Cruz offered only one possible interpretation of these differences – the existence of large, fundamental errors in model physics (refs. 2, 21). In addition to this possibility, there are at least three other plausible explanations for the warming rate differences shown in Exhibit A: errors in the human (refs. 2225), volcanic (refs. 2630), and solar influences (refs. 24, 31) used as input to the model simulations; errors in the observations (discussed above) (refs. 220); and different sequences of internal climate variability in the simulations and observations (refs. 23, 24, 30, 3236). We refer to these four explanations as “model physics errors,” “model input errors,” “observational errors,” and “different variability sequences.” They are not mutually exclusive. There is hard scientific evidence that all four of these factors are in play (refs. 220, 2236).
“Model input errors” and “different variability sequences” require a little further explanation. Let’s assume that some higher extraterrestrial intelligence provided humanity with two valuable gifts: a perfect climate model, which captured all of the important physics in the real-world climate system, and a perfect observing system, which reliably measured atmospheric temperature changes over the last 18 years. Even with such benign alien intervention, temperature trends in the perfect model and perfect observations would diverge if there were errors in the inputs to the model simulations [h], or if the purely random sequences of internal climate oscillations did not “line up” in the simulations and in reality (refs. 23, 24, 30, 3236).
In short, “all models are too sensitive to CO2” is not the only valid explanation [i] for the modeldata differences in Exhibit A (refs. 2, 11, 13, 18, 2224, 26, 30, 3238). Dozens of peer-reviewed scientific studies show that the other three explanations presented here (“model input errors,” “observational errors,” and “different variability sequences”) are the primary reasons for most or all of the warming rate differences in Exhibit A [j].  
But what if climate models really were a factor of three or more too sensitive to human-caused GHG increases, as claimed by the majority side of the subcommittee? The telltale signatures of such a serious climate sensitivity error would be evident in many different comparisons with observations, and not just over the last 18 years. We’d expect to see the imprint of this large error in comparisons with observed surface temperature changes over the 20th century (refs. 3742), and in comparisons with the observed cooling after large volcanic eruptions (refs. 30, 43, 44). We don’t. There are many cases where observed changes are actually larger than the model expectations (refs. 41, 42), not smaller.
In assessing climate change and its causes, examining one individual 18-year period is poor statistical practice, and of limited usefulness. Analysts would not look at the record of stock trading on a particular day to gain reliable insights into long-term structural changes in the Dow Jones index. Looking at behavior over decades – or at the statistics of trading on all individual days – provides far greater diagnostic power. In the same way, climate scientists study changes over decades or longer (refs. 3942, 45), or examine all possible trends of a particular length (refs. 23, 38, 4648). Both strategies reduce the impact of large, year-to-year natural climate variability [k] on trend estimates. The message from this body of work? Don’t cherry-pick; look at all the evidence, not just the carefully selected evidence that supports a particular point of view.
In summary, the finding that human activities have had a discernible influence on global climate is not falsified by the supposedly “hard data” in Senator Cruz’s Exhibit A. The satellite data and weather balloon temperatures are not nearly as “hard” as they were portrayed in the hearing. Nor is a very large model error in the climate sensitivity to human-caused GHG increases the only or the most plausible explanation for the warming rate differences in Exhibit A. Indeed, when the observational temperature data sets in Exhibit A are examined over their full record lengths – and not just over the last 18 years – they provide strong, consistent scientific evidence of human effects on climate (refs. 41, 42, 48)  as do many other independent observations of changes in temperature, the hydrological cycle, atmospheric circulation, and the cryosphere (refs. 41, 42).
Climate policy should be formulated on the basis of both the best-available scientific information and the best-possible analysis and interpretation. Sadly, neither was on display at the Senate hearing on “Data or Dogma?” There was no attempt to provide an accurate assessment of uncertainties in satellite data or to give a complete and balanced analysis of the reasons for short-term differences between modeled and observed warming rates. Political theater trumped true “open inquiry.”
Climate change is a serious issue, demanding serious attention from our elected representatives in Washington. The American public deserves no less.  


We gratefully acknowledge the comments and valuable suggestions from Professor Susan Solomon (M.I.T.) and Dr. Mike MacCracken (The Climate Institute). 


  1. Prof. John Christy from the University of Alabama at Huntsville.
  2. MSU estimates of the temperature of tropospheric layers also receive a small contribution from the temperature at Earth’s surface.
  3. This conversion process relies on an atmospheric radiation model to invert the observations of outgoing, temperature-dependent microwave emissions from oxygen molecules. Since oxygen molecules are present at all altitudes, the microwave flux that reaches the satellite is an integral of emissions from thick layers of the atmosphere.  
  4. At the end of the hearing, Senator Cruz questioned the reliability of thermometer measurements of land and ocean surface temperature and highlighted the large adjustments to “raw” surface temperature measurements (adjustments which are necessary because of such factors as changes over time in thermometers and measurement practices). He did not mention that the surface temperature adjustments are typically much smaller than the adjustments to “raw” MSU data (refs. 2, 3, 8).
  5. This transition occurred in 1998, at the beginning of the 18-year “no significant warming” period highlighted by Senator Cruz.
  6. For example, over the longer 1979–2014 analysis period, tropospheric warming is a robust feature in all observational TMT datasets. For shorter, noisier periods (such as 1996–2014), the sign of the TMT trend is sensitive to dataset construction uncertainties.
  7. Disappointingly, Exhibit A neglects to show at least one weather balloon temperature data set with substantial tropospheric warming over the last 18 years (18).
  8. Such as leaving out volcanic cooling influences that the real world experienced (refs. 23, 24, 26–30).
  9. The model results shown in Exhibit A are from so-called “historical climate change” simulations. These simulations involve changes in a number of different human and natural influences (e.g., human-caused changes in GHG levels and particulate pollution, and natural changes in solar and volcanic activity). They are not simulations with changes in GHG levels only, so it is incorrect to interpret the model-versus-observed differences in Exhibit A solely in terms of model sensitivity to GHG increases.   
  10. Another incorrect claim made at the hearing was that the mainstream scientific community had failed to show the kind of model–data comparisons presented in Exhibit A. Results similar to those in Exhibit A have been presented in many other peer-reviewed publications (refs. 2, 13, 18, 23, 24, 30, 32, 35, 38, 46, 47).
  11. Such as the variability associated with unusually large El Niño and La Niña events, which yield unusually warm or cool global-mean temperatures, respectively. The El Niño event during the winter of 1997 and spring of 1998 was likely the largest of the 20th century and produced a large warming “spike” in surface and tropospheric temperatures.


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