Straight talk from Kevin Trenberth on denialists, climate science communication, and climate change policy


In a paper presented at the American Meteorological Society meeting in January, leading climate scientist and IPCC lead author Kevin Trenberth talks about climate change deniers, ‘climategate’, the IPCC assessments, the media, and politicians. He challenges the climate science community to stop making so many type II errors and being so reticent about discussing policy options. And he challenges the policy community to focus much more on the need for long-range preparedness planning for the likely disastrous consequences of climate change.

h/t Rabett Run

Dr. Kevin E. Trenberth is Head of the Climate Analysis Section at the U.S. National Center for Atmospheric Research in Boulder, Colorado. From New Zealand, he obtained his Sc. D. in meteorology in 1972 from Massachusetts Institute of Technology. He was a lead author of the 1995, 2001 and 2007 Scientific Assessment of Climate Change reports from the Intergovernmental Panel on Climate Change (IPCC), and shared the 2007 Nobel Peace Prize which went to the IPCC. He served from 1999 to 2006 on the Joint Scientific Committee of the World Climate Research Programme (WCRP). He has published over 450 scientific articles or papers, including 47 books or book chapters, and over 198 refereed journal articles. He is listed among the top 20 authors in highest citations in all of geophysics.

Trenberth dedicates his paper, “Communicating Climate Science and Thoughts on Climategate”, in honor of Stephen Schneider. This post excerpts some of the text, in order to convey the range of themes Trenberth touches on and as a show of support for what he is saying. It needs to be heard beyond the perimeter of the AMS meeting. The full article is posted online here.

On ‘climategate’:

The selective publication of some stolen emails taken out of context and distorted is mischievous and cannot be considered a genuine attempt to engage with the climate change issue in a responsible way. Instead there should be condemnation of the abuse, misuse and downright lies about the emails. … I was involved in just over 100 of the hacked email messages …

On climate assessments and denialists:

Scientists make mistakes and often make assumptions that limit the validity of their results. They regularly argue with colleagues who arrive at different conclusions. These debates follow the normal procedure of scientific inquiry.

The IPCC assessments are a means of taking stock and avoiding some of the “noise” created by the different approaches and thereby providing conservative but robust statements about what is known and what is not.

But their critics are another matter entirely, and their false claims have not been scrutinized or criticized anything like enough! Perhaps climategate comes from the somewhat inept response of climate scientists to criticisms from various sources. The climate change deniers have very successfully caused major diversions from the much needed debate about what to do about climate change and how to implement it. It is important that climate scientists learn how to counter the distracting strategies of deniers.

On the media and denialists:

The media have been complicit in this disinformation campaign of the deniers. Climate varies slowly and so the message remains similar, year after year — something not exciting for journalists as it is not “news”. Controversy is the fodder of the media, not truth, and so the media amplify the view that there are two sides and give unwarranted attention to views of a small minority or those with vested interests or  ideologies.  The climate deniers have been successful in by-passing peer review yet attracting media attention. In those respects the media are a part of the problem. But they have to be part of the solution.

On scientists and denialists:

The main societal motivation of climate scientists is to understand the dynamics of the climate system (both natural and human induced), and to communicate this understanding to the public and governments. … They find it disturbing that blogs by uninformed members of the public are given equal weight with carefully researched information backed up with extensive observational facts and physical understanding. As Thomas Friedman noted on “Meet the Press” 6 September 2009, the internet is an “open sewer of untreated, unfiltered information.” Moreover, “the American public is incapable of deciphering between facts, fiction and opinion” …

While statements about climate change are cautious and all sorts of caveats are applied by scientists, or else they are criticized by colleagues, the same is not true for the deniers. Many scientists withdraw from the public arena into the Ivory Tower after being bruised in skirmishes with the public via the press.

Trenberth makes some observations about how climate science communication should be framed.

On “type II errors” and communicating the role of global warming in climate:

Many scientists also do not help with regard to communicating the role of global warming in climate. Prior to the 2007 IPCC report, it was appropriate for the null hypothesis to be that “there is no human influence on climate” and the task was to prove that there was. The burden of proof is high. In general in this case, scientists assume that there is no human influence and to prove that there is requires statistical tests to exceed the 95% confidence level (5% significance level) to avoid a chance finding of a false positive. To declare erroneously that the null hypothesis is not correct is called a type I error, and the science is very conservative in this regard about making such an error. Scientists are thus prone to make what are called type II errors whereby they erroneously accept the null hypothesis when it is in fact false.

Given that global warming is “unequivocal”, and is “very likely” due to human activities to quote the 2007 IPCC report, the null hypothesis should now be reversed, thereby placing the burden of proof on showing that there is no human influence. … As a whole the community is making too many type II errors.

So we frequently hear that “while this event is consistent with what we expect from climate change, no single event can be attributed to human induced global warming”. Such murky statements should be abolished. On the contrary, the odds have changed to make certain kinds of events more likely. For precipitation, the pervasive increase in water vapor changes precipitation events with no doubt whatsoever. Yes, all events! …

It is not a well posed question to ask “Is it caused by global warming?” Or “Is it caused by natural variability?” Because it is always both. It is worth considering whether the odds of the particular event have changed sufficiently that one can make the alternative statement “It is unlikely that this event would have occurred without global warming.” For instance, this probably applies to the extremes that occurred in the summer of 2010: the floods in Pakistan, India, and China and the drought, heat waves and wild fires in Russia. It likely also applies to the flooding in Queensland, Australia in January 2011.

On communicating about what is to be done:

When asked about what could and should be done about climate change, many scientists back away for fear of being labeled advocates. However, scientists should note that the IPCC strives to carry out policy relevant but not policy prescriptive science assessments, with considerable success. Given the physical science findings, what are the ramifications for society and the environment? It is important for scientists to recognize that Working Group II of IPCC deals extensively with the past and future expected impacts of climate change, the vulnerabilities that exist, and the adaptation and coping strategies for dealing with these. Similarly, Working Group III deals with options for mitigating the problem by reducing future emissions of greenhouse gases. Scientists should recognize that these options exist and, to the extent they are familiar with them, state what they are. Scientists should also be aware of the national and international discussions and negotiations underway to address the problem. …

Personally, I close this aspect of my presentations with a statement that “you will be affected by climate change, and you already are, whether you believe it or not. But more than that, you will be affected by the outcomes of legislation and international treaties, perhaps even more!”

On ill-informed and corrupt politicians:

The argument is that to make decisions, all aspects of the problem must be taken into account and it is the politicians who are supposed to do this, not the scientists, in order to represent all interests. My own observation is that while some politicians are indeed well informed and understand their role, most are not. The corrupting influence of funding from all sources of vested interests prevents many of them from doing the right thing on behalf of the country and civilization as a whole. It is clear that climate science has become politicized, and scientists are slow to recognize this. Politicians hide behind the apparent uncertainties and have failed to act. …

Finally, Trenberth turns to a problem that Climate Science Watch has been concerned with — what we refer to as the need for climate change preparedness.

On the limits of mitigation and the likelihood of disastrous global climatic disruption:

Environmental groups and one segment of scientists have focused on what is called “mitigation” that aims to reduce emissions of greenhouse gases and slow and ultimately stop climate change in its tracks. Decarbonizing the economy is very important for many reasons, not the least of which is climate change. However, by itself, I view this as short-sighted, as the steps required are so revolutionary as to be highly unlikely to be achieved. Instead, we must recognize that while there is considerable merit in slowing the pace of climate change, and we should work to reduce emissions, it is also essential that much stronger steps be taken to plan for and adapt to the change that is surely coming. How we cope with challenges ahead and build more resiliency in our system, are major questions that should be higher on the agenda.

The major failures in making progress, such as in Copenhagen in December 2009, imply that we should be more accepting that climate disasters are inevitable, along with environmental refugees, and so what are we going to do with them? … The summer of 2010 with floods in Pakistan, India, and China, and devastating drought, heat waves and wild fires in Russia, is a case in point. Indeed, 2010 provided many such examples from the New England flooding and “Snowmageddon” in the Washington D.C. area in February and March to the flooding in California associated with a “Pineapple Express” of moisture from extending from the Hawaiian Islands to California in December. Growth of these disasters into a major catastrophe, war and strife, is something to be avoided if at all possible, but it is likely where we are headed. …

Unfortunately, society is not ready to face up to these challenges and the needed changes in the way we create order and govern ourselves. [A] number of pragmatic steps are possible, but they require planning for decades ahead, not simply the time until the next election.

On the need for a climate service and regular assessments:

Waiting 6 years for the next IPCC report is not an option. The media continue to report highly misleading material about how cold outbreaks, snow events, or one cold month nullifies global warming when the big picture continues to indicate otherwise.

Routine climate services and regular assessments of the state of the climate and the short-term prognosis as part of a climate service, much as is done for weather forecasts, is an essential development. At present this is being approached at best in a piecemeal fashion, and the needed investment is not available. It should be a high priority and linked to any climate legislation on mitigation and adaptation. …

Far too little is happening on all fronts: communicating and informing the public, reducing emissions and building new energy infrastructure by decarbonizing the economy (mitigation), and planning to cope with future climate change and its consequences.

Earlier posts:

House votes 244-179 to kill U.S. funding of IPCC

The Importance of Science in Addressing Climate Change: Scientists’ letter to the U.S. Congress

Climate scientists form rapid response media team to counter denialist claims

“Preparing for Climate Change” – Steve Schneider continues to confront us with inconvenient truths

Ben Santer on the attribution of extreme weather events to climate change

Interview with Stephen Schneider on climate science expert credibility study

Latest NRC report charts path for federal government in supporting national climate preparedness

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