Growing up in the 80s and 90s in Chevy Chase, Maryland, an inside-the-Beltway suburb, I only learned one thing about fossil fuels: they were causing global warming. That is, the CO2 my parents’ SUV was producing was making the Earth a lot hotter and that would make a lot of things worse. Oh, and one more thing: that this was a matter of scientific consensus.
Looking into the issue a bit, I found that there were professionals in climate science, such as Richard Lindzen of MIT, and Patrick Michaels of the University of Virginia, who said that global warming wasn’t the big deal it was made out to be. But they seemed to be very much in the minority. Who was right? Of course, I knew the majority isn’t always right—but it certainly isn’t always wrong.
What was I supposed to make of all this? I think this is a predicament most of us experience. On the one hand, there is something authoritarian about calls to obey “consensus” such as John Kerry’s recent “When 97 percent of scientists agree on anything, we need to listen, and we need to respond.” On the other hand, there is something anti-science about the militant skepticism of some critics of the “climate change consensus.” For instance, ExxonMobil CEO Rex Tillerson says: “The term scientific consensus is an oxymoron in itself.” Not true. How can we possibly function in a complex division-of-labor society if we don’t consult experts—which includes learning about what there is consensus on (and what there isn’t) among the experts in different fields?
Scientific consensuses are an important part of any modern society—they tell us the general state of agreement in a field, not so we can blindly obey the experts in question (experts and consensuses can be wrong) but so that we can understand and critically think about those experts’ views. For example, if you are thinking about nutrition, it is a valuable starting point to know where there is general agreement, where there isn’t, and why. If I read a book endorsing a controversial diet, I can’t really have a responsible opinion until I know what most experts in the field think about the issues—including whether they have powerful arguments against the book’s claims that I couldn’t have thought of myself.
Thus, statements of scientific consensus can be extremely valuable tools. But they are only valuable, and only scientific, if they are explained clearly to the public. We need to know exactly who agrees with what for what reasons, and just as importantly, where there is disagreement within the consensus and for what reasons.
For example, it makes a big difference if there is a consensus that there is some global warming vs. a consensus that there will be catastrophic global warming. It makes a big difference if the consensus is based on issues that the experts have expertise on, such as climate records, vs. issues that they do not have expertise on, such as the economics of fossil fuels vs. solar and wind. Most consensus statements, however, are very unclear on who agrees with what and why. They are unscientific consensuses—misrepresentations of the state of scientific opinion designed to further a political agenda.
Take the consensus statement of the American Geophysical Union, which can be found in its entirety here. Like most consensus documents, it starts with something there is definitely a consensus on: “Extensive, independent observations confirm the reality of global warming.” But then, with equal certainty, it cites dramatic predictions of climate models that, even the Intergovernmental Panel on Climate Change reluctantly acknowledged, demonstrably failed to predict the climate of the past two decades. And still, with equal certainty, it calls for “urgent” political action to reduce fossil fuel use—with no acknowledgment of the cost of doing so.
Are observations, dramatic model predictions, and complex political decisions really all on the same scientific footing? No—but this kind of statement makes it seem as if they are all a matter of expert consensus.
I have spent quite a bit of time querying experts on this issue, and in my understanding the actual consensus in the field is something like the following.
When CO2 is added to the atmosphere it, all things being equal, has a mild, decelerating (logarithmic) warming effect; each additional CO2 molecule leads to less warming than the last. This effect has made some contribution to the widely-accepted .8 degrees C average warming in the last 150 years.
Within this consensus, there is considerable disagreement about whether other aspects of the atmosphere, called “feedbacks,” significantly amplify the CO2-induced warming or not. This is called the issue of “climate sensitivity.” More climate scientists than not seem to believe in significant climate sensitivity, as evidenced by the fact that the computer models used to predict climate are based on the assumption of significant climate sensitivity.
At the same time, there is also consensus that in the last 15+ years there has been no significant global warming, despite record, accelerating CO2 emissions, and the climate models based on high sensitivity failed to predict this. There is dispute over whether and to what extent this supports the low-sensitivity theory of CO2. (Here is an account of the data and debate.)
I could go on about the consensus or lack thereof on other issues—the relationship between warming and extreme weather events, whether there have been significant changes in extreme weather events, etc.—but the point is I want the field of climate science to do that, so that we can think critically about it and ask questions.
What it shouldn’t be doing—but is—is telling us what political policies, namely fossil fuel policies, to adopt. The question of fossil fuel policy is an interdisciplinary one covering many fields that climate scientists are not experts on.
That means we need botanists to explain to us the potential benefits of increased CO2 in the air for plant growth. We need economists to share their knowledge about the consequences of more expensive energy if fossil fuels are restricted—and the capacity of human beings to adapt to climate change (man-made or not) over a period of decades. We need energy experts to tell us how far away solar, wind, and other alternatives are from providing the benefits of fossil fuels. We need geographers to share their knowledge on whether the climate has become more or less livable as we’ve used fossil fuels.
Having tried to get this information myself from these fields, I believe that if the state of knowledge and agreement in each field were objectively presented, we would conclude that the consequences of continuing to use large amounts of fossil fuels would be overwhelmingly positive to human life, and the consequences of restricting them would be overwhelmingly negative. But right now it’s hard for anyone to know what to conclude, because in today’s “consensus” statements, representatives of scientific fields neither explain the state of knowledge precisely, nor do they stick to their area of specialization.
Take a look at the NASA Global Climate Change Consensus page, which features 18 different consensus statements from professional scientific societies. The vast majority of these organizations don’t specialize in climate science, yet they make definitive statements about climate science. And many also use their scientific credibility to demand specific political policies.
The prestigious American Physical Society says “We must reduce emissions of greenhouse gases beginning now.” Really? Many in the fields of energy and economics have argued that forced reductions in greenhouse gases would lead to catastrophic consequences for human life, particularly in developing countries that need affordable energy to develop. As an association of physicists with no specialized knowledge of these issues, it is an abuse of scientific standing for the American Physical Society to support specific energy policies. A proper consensus statement by physicists would educate us about the physics of climate, not the politics of physicists.
I say, bring on the scientific consensus about climate change—and the scientific consensuses about everything else related to energy and environmental policy. Knowing what specialists in these fields think would be truly valuable information for our critical thinking about vital issues. But it’s time to stop the intimidation and manipulation. It’s time to throw out the unscientific consensus.