In this extract from Uncertainty: How It Makes Science Advance, Kostas Kampourakis and Kevin McCain discuss the discrepancy between scientific consensus on climate change and public opinion, and what can be done to fix it.
In a May 2014 interview, then US President Barack Obama claimed that climate change “is not some distant problem of the future. This is a problem affecting Americans right now.” This is not just an American problem, of course. Climate change is something that affects everyone in the world.
According to the Intergovernmental Panel on Climate Change (IPCC), a group of hundreds of climate scientists, “it is very likely that…extreme precipitation events will become more intense and frequent in many regions. The ocean will continue to warm and acidify, and global mean sea level to rise.”
“Warming of the climate is unequivocal” — in fact, “the period from 1983 to 2012 was likely the warmest 30-year period of the last 1,400 years in the Northern Hemisphere.” These temperature records are the result of careful measurements made with thermometers and other instruments. And they have been corroborated by looking at things like tree rings and ice cores. The evidence from tree rings and ice cores is independent of the temperature measurements taken; therefore there is independent evidence converging in support of increasing global temperatures, and this is very important to note.
In addition to rising temperatures, there is also the fact that human emissions of greenhouse gases are the highest they have ever been. Our emissions of CO2 today are six times higher than they were in 1950! Why does this matter? Because the best explanation for the rapid increase in global temperatures is that it is the result of higher levels of greenhouse gases in the atmosphere. Greenhouse gases in the atmosphere trap heat that would otherwise escape the planet.
This cursory examination of the evidence for climate change is sufficient to demonstrate that there is strong evidence from a variety of sources for climate change. Does this evidence make climate change certain? No. It is possible (in the broad sense of the term) that the evidence for climate change is misleading or that it has been misinterpreted. Nevertheless, the odds of either of these are miniscule. To put the strength of evidence for climate change in perspective, Romm has pointed out that scientists are as sure that climate change is real and “that humans are responsible for [the] most recent climate change as they are that cigarettes are harmful to human health.” Are they certain? No, but quite sure nevertheless!
Scientists are as sure that climate change is real and “that humans are responsible for the most recent climate change as they are that cigarettes are harmful to human health.” Are they certain? No, but quite sure nevertheless!
Although the evidence in support of climate change and the role that humans are playing in it is strong, uncertainties remain. This is not something that climate scientists deny. In fact, the IPCC is explicit about the known uncertainties surrounding the statements that it makes. For example, in its 2014 Synthesis Report, the IPCC labeled each of its claims from virtually certain (99–100%) to extremely unlikely (0–5%). Hence, even the best grounded of the claims that the IPCC makes is not certain — even virtually certain statements are held to be somewhere between 99% and 100%.
Has the uncertainty caused a lack of consensus among scientists concerning the reality of climate change and human influence upon it? No. The IPCC is not the only organization to have claimed that humans are causing global warming and climate change; this is the case for all major scientific bodies in the United States whose expertise bears directly on the matter. The fact is that “virtually all professional climate scientists agree on the reality of human induced climate change.”
Given the widespread consensus among climate scientists it may seem a bit puzzling that a third of the people in the United States are not aware of it and more than half underestimate how large the consensus is. There are likely a number of reasons for this confusion. One reason stems from the fact that “virtually all” is not all. There are some climate scientists who deny that human actions have a major causal influence on the global climate. On its own this would not explain the misperception of how strong the consensus is.
The media has a desire to be perceived as fair and unbiased. “Fair and unbiased” is many times interpreted as reporting on both sides of an issue. In itself, this is not a bad thing. However, it can be deeply misleading to the general public watching the program.
Another reason that the consensus may be misperceived by the public comes from how the issue of climate change is treated by the media. Oreskes correctly pointed out that “the mass media have paid a great deal of attention to a handful of dissenters in a manner that is greatly disproportionate with their representation in the scientific community.” Presumably, this often occurs because the media has a desire to be perceived as fair and unbiased. “Fair and unbiased” is many times interpreted as reporting on both sides of an issue. So when news programs have a climate scientist speak about climate change they will often find another scientist who denies the consensus to offer an opposing viewpoint. In itself, this is not a bad thing. However, it can be deeply misleading to the general public watching the program. The average viewer sees two scientists disagreeing about an issue. They typically are not told that the scientist speaking in favor of the consensus view is representative of thousands of other scientists, whereas the dissenting scientist is representative of just a handful. This sort of disproportionate representation is very problematic, and it is apt to confuse the average viewer about the degree of consensus there is on this issue.
None of this is to say that the consensus view must be correct. However, the evidence in support of climate change is solid, and there is almost unanimous agreement on the issue from the experts. We have ways of mitigating the uncertainty present in climate models to some degree by making use of techniques like robustness analysis. Nevertheless, this is not perfect; uncertainties remain. At the end of the day, the best we can do is follow the evidence and act accordingly. Despite the uncertainties inherent in climate science, we have strong evidence that climate change is happening largely because of human activities.
Kostas Kampourakis is the author and editor of several books about evolution, genetics, philosophy, and history of science. From 2015 to 2019 he was the Editor-in-Chief of the journal Science & Education. He is currently a researcher at the University of Geneva, where he also teaches at the Section of Biology and the University Institute for Teacher Education.
Kevin McCain is an Associate Professor of Philosophy at the University of Alabama at Birmingham. His research is primarily focused on epistemology and philosophy of science, particularly where the two intersect. He is a series editor for Routledge Studies in Epistemology and the author of numerous works in epistemology and philosophy of science.