The United Nations Intergovernmental Panel on Climate Change (IPCC) is about to release its Fifth Assessment Report on the state of climate science. Previous reports were released in 1990, 1995, 2001 and 2007. The New York Times trumpets the release in an article entitled “Climate Panel Cites Near Certainty on Warming”. The Times is always eager to opine rather than report, and the title of this article strays beyond misleading into the realm of the just plain wrong.
The actual statement in the report is “It is extremely likely that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951 to 2010…” The Fourth Assessment Report from 2007 assigned a 90% confidence level to this statement, while the newest report assigns a 95% confidence levels. Bear in mind that these numbers represent the Committee’s opinion regarding the likelihood that the Committee’s opinion is correct. In essence, the new report says, “Six years ago I was 90% sure I was right, but now I’m 95% sure I’m right.” This statement is blather, not science.
The IPCC is a panel of experts appointed by governments to assess the current state of climate science by counting up the number of peer-reviewed journal articles supporting various viewpoints on climate. It is not a scientific body, and it does no research on climate. Although a large number of scientists participate in the IPCC’s activities, its management is firmly in the hands of people advocating for strong action to reduce carbon emissions.
As I have stated many times in this blog, science is not a process by which we survey the opinions of scientists. For example, we cannot find out whether there is life on Mars by asking planetary scientists their opinions. The reality is, we just don’t know whether there is life on Mars and will not know until we have actual evidence.
During the Middle Ages, the Catholic Church addressed questions about the natural world by convening conferences of scholars, usually clerics, to review scripture and reach conclusions. People who challenged those conclusions were branded heretics and subject to oppression, torture and even death for their impertinence. Copernicus, Galileo and a few other brave souls offered an alternative approach: Establish a hypothesis (e.g., the Earth revolves around the Sun, not vice-versa) and then test the hypothesis against empirical evidence. The IPCC is behaving like the Catholic Church, not like Galileo.
To apply science to the climate change issue, we need to be precise about the hypotheses being debated. There are in fact not one but four. The first hypothesis is that the Earth has warmed at a rate of about 1º C over the last 100 years. There are some methodological issues around temperature measurements, but the empirical support for this hypothesis is pretty good.
The second hypothesis is that this temperature rise is unusual in the geologic record. The problem here is that we have excellent temperature records since about 1970, good records from 1900 to 1970, scattered records from about 1800 to 1900 and not much before 1800. Two hundred years is nothing in geological time, so some climate change advocates have attempted to create indirect data series by examining tree rings, ice cores and other indicators. There is absolutely no consensus on whether these data sets are meaningful, and the “climategate” email scandal strongly suggests a great deal of mischief and manipulation in their construction.
The third hypothesis is that human emissions of carbon dioxide and other greenhouse gases (ghg) are the main cause of the most recent hundred-year warming trend. It’s this point that the Times is addressing when it calls warming “near certain”. This may be correct, but it’s not the central issue. The heart of the debate is the fourth hypothesis which is that continued growth in atmospheric ghg concentrations will cause warming to accelerate. There is no empirical support for this view and some strong logical reasons it may not be true.
The Times, as always, focuses on the very high end of the IPCC projections, which shows a temperature increase of 5º C in response to a doubling of atmospheric carbon dioxide. The Times is happy to point out that the consequences of such warming would be dire indeed. The new IPCC report, however, shows a new low estimate of 2.7º C, rather than the 3.6º C number from the 2007 report. In other words, the IPCC is now saying that the problem could be just as bad as they have said before, but could be significantly less severe. The Times downplays this powerful statement as meaningless, claiming that the new low estimate is only “possible”, not “likely”. To further undermine the 2.7º C number, the Times article informs readers that “Michael E. Mann, a climate scientist at Pennsylvania State University, said he feared the intergovernmental panel, in writing its draft, had been influenced by criticism from climate doubters, who advocate even lower numbers.” In other words, the IPCC is authoritative when it presents an apocalyptic vision, but not when it offers any cautionary notes.
How likely is the high end estimate? We know from basic physics the direct warming impacts of carbon dioxide concentrations in the atmosphere. Expected growth in ghg emissions, however, would suggest a temperature increase of only about 1º C by 2100, below even the IPCC’s low end. The higher numbers come from a series of highly questionable assumptions regarding the impact of feedback loops in the climate system. For example, as temperature rises, cloud formation increases. The bottoms of clouds can trap additional heat, amplifying the warming. The tops of clouds, however, can reflect sunlight back into space, reducing warming. Which effect will predominate? How much carbon can the oceans absorb, and what impact would that have on climate? What about surface vegetation? The IPCC numbers assume that all the feedback effects are positive. In other words, direct warming is always aggravated by indirect effects, and never mitigated. Is that a good assumption?
There’s no theoretical or empirical evidence to suggest that feedback loops are positive rather than negative. In fact, a basic principle of physical science, known as “Le Chatelier’s principle” states that “Any change in status quo prompts an opposing reaction in the responding system.” The key tenet of the environmental movement is that natural systems are fragile and prone to collapse if disturbed. In contrast, Le Chatelier’s principle says that natural systems are robust and can compensate for disturbances. Note that Le Chatelier did not claim that disturbances don’t change or disrupt natural systems or that there is no cost to these changes, only that natural systems tend to recover to a new equilibrium. Anthropogenic ghg emissions may indeed lead to a warmer world, but there is no basis at present for believing the “tipping point” argument which predicts climate catastrophe. One reason for the high warming numbers generated by the IPCC is that all the climate models considered by the IPCC use similar sets of assumptions. The IPCC does not use any models which take a fundamentally different view of the issue.
If the climate science is so weak, how can the IPCC reach such powerful and definitive conclusions? The main reason is that the IPCC was established precisely for the purpose of advocating for carbon reductions, and its management is more than happy to feed the public a diet of scary scenarios. There are more subtle reasons as well.
Under more normal, less politicized circumstances, a literature review might give you a good sense of the range of scientific views on a particular subject. If you want to know, for example, how old the universe is, a literature review would probably tell you something about the state of the science. Very few people, however, have a vested interest in the outcome of that debate. Climate change is different. Tens of billions of dollars in funds are for climate research, but with a major bias. Check, for example, the climate research funding by the US National Science Foundation, which you can find at http://www.nsf.gov/news/news_summ.jsp?cntn_id=128415. The funding description includes the following telling statement, “The consequences of climate variability and change are becoming more immediate and profound than anticipated, research has found.” This is a clear signal to applicants on what the NSF wants. Examples of the topics for NSF research grants are “Quantifying and conveying the risk of prolonged drought in coming decades” and “Exploring the connection between wildfires and regional climate variability”. Little if any of this money is going to scientists who question the catastrophic climate scenarios. To get this money, you need to be a team player.
Moreover, many of the scientific and climate journals are edited by people who are strong political advocates for carbon reduction policies. As a result, there is a biased selection of articles accepted for publication. By analogy, the American electorate is divided roughly 50/50 between the political left and the political right. You could never find this out by counting the articles printed by the New York Times, the Washington Post, the Los Angeles Times and the Boston Globe. Such a review would suggest that 95% of the political opinion in the country is on the political left. These publications are not dishonest, just biased.
I also wonder how many scientists, most of whom live in academic communities, are dissuaded from either researching climate or expressing their real views because they are frightened of the reputational, social and career consequences of expressing politically incorrect opinions.
The bottom line here is that the empirical support for the catastrophic climate hypothesis has been deteriorating not growing over the years, primarily because climate models remain unable to make any correct predictions about the response of climate to increased atmospheric carbon concentrations. Regarding the biggest problem of climate models – the 15-year plateau of global temperatures – the Times is contemptuous, claiming that “The [IPCC] scientists, whose findings are reported in a draft summary of the next big United Nations climate report, largely dismiss a recent slowdown in the pace of warming, which is often cited by climate change doubters, attributing it most likely to short-term factors.” If “short-term factors” overwhelm your calculations, then you clearly do not understand the phenomenon you are studying. Perhaps the Sixth Assessment Report, due around 2020, will begin to get this right, but I wouldn’t hold my breath.