Skeptics Don’t Need to “Know” the Future to Manage Climate Risks
The most important contribution of the recent National Climate Assessment to our conversation on climate change may very well be its focus on risk assessment, allowing us to shift the conversation away from a singular focus on not “knowing” the future toward a more useful focus on the probable risks associated with unmitigated climate change.
Those unwilling to accept the strong scientific consensus on climate change have long insisted that we simply need to attain a greater degree of knowledge before taking action. In response, scientists have done more research, written more reports, and presented more evidence. But the problem is that we’ve long since reached a scientific consensus on climate change and no matter how much additional evidence is gathered and communicated, climate change skeptics will remain unmoved.
This impasse may have less to do with a basic misunderstanding of the scientific process and the nature of scientific knowledge than with the way our conversation remains stuck in the domain of epistemology as opposed to that of probability-based risk analysis.
Enough Talk about Beliefs and Knowledge
Philosophers make a distinction between beliefs and knowledge, but the two go hand-in-hand within the study of epistemology. The main distinction is this: Beliefs lack justification, but knowledge must have good grounds for supposing something to be true.
To believe something, I don’t need any grounds for doing so. I can believe the earth is round simply on a hunch without possessing any justification for my belief. In this case, my belief happens to be true. But I can just as easily believe the earth is flat. The point is that beliefs do not require any justification and do not constitute knowledge per se. To know something, however, does require justification. To know that the earth is round, I need grounds beyond just my belief that this is the case. In other words, I need some form of justification.
Scientific knowledge is justified through various forms of evidence — observations, experiments, etc. The strength of the evidence that contributes to knowledge can be debated, of course. But science has a process — the scientific method — to systematically examine the evidence supporting knowledge claims. As this process unfolds, advances take place to refine, revise, and strengthen what we know to be true.
The catch, of course, is that scientific knowledge is in a continual process of development. Absolute knowledge is antithetical to the scientific process.
We can know something to be true and we can “prove” something insofar as we arrive at a consilience of evidence — a convergence or concordance of evidence derived from multiple independent and unrelated sources, which leads to a general agreement, or scientific consensus — but we can never “prove” something to a degree of absolute certitude.
As physicist Max Born, known for his contributions to quantum mechanics, remarked, “ideas such as absolute certitude, absolute exactness, final truth, etc. are figments of the imagination which should not be admissible in any field of science.”
Climate science is a textbook example of how multiple lines of research arrived at a convergence of evidence and a strong scientific consensus. As documented by Cook and colleagues (2016), “The consensus that humans are causing recent global warming is shared by 90%–100% of publishing climate scientists according to six independent studies by co-authors of this paper. Those results are consistent with the 97% consensus reported by Cook et al (Environ. Res. Lett. 8 024024).”
A strong scientific consensus is the gold standard for any form of scientific knowledge. It will never get better than that. But as long as discussions about climate change remain stuck in the discourse of epistemology, the inevitable lack of absolute knowledge will be a sticking point for those who argue we must not take action until that unattainable threshold has been met.
Let’s Talk Risks Instead
The solution is to shift the conversation toward discussion of probable risks rather than (absolute) knowledge; and Volume II of the National Climate Assessment opens the door to doing just that.
A discussion of risks helps dislodge the need for absolute certainty in what Ángel Pinillos refers to as “skeptical pressure” cases. In a recent New York Times column, Pinillos points out how, in such cases, we can feel as if we “don’t know something even when possessing enormous evidence in its favor.”
Philosophers call scenarios like these “skeptical pressure” cases, and they arise in mundane, boring cases that have nothing to do with politics or what one wants to be true. In general, a skeptical pressure case is a thought experiment in which the protagonist has good evidence for something that he or she believes, but the reader is reminded that the protagonist could have made a mistake. If the story is set up in the right way, the reader will be tempted to think that the protagonist’s belief isn’t genuine knowledge.
Climate change skepticism is a perfect example. No matter how great the scientific consensus, climate change skeptics will always focus on the small percentage of evidence that disconfirms the generally agreed upon findings. The problem with skeptical pressure cases like climate change is that we end up stuck in that impossible pursuit of absolute certainty. Skeptics keep us bogged down in what we don’t know and we lose sight of how much we really do know (the consilience of evidence and the scientific consensus).
One way to counter the effects of skepticism is to stop talking about “knowledge” and switch to talking about probabilities. Instead of saying that you don’t know some claim, try to estimate the probability that it is true. As hedge fund managers, economists, policy researchers, doctors and bookmakers have long been aware, the way to make decisions while managing risk is through probabilities. Once we switch to this perspective, claims to “not know,” like those made by Trump, lose their force and we are pushed to think more carefully about the existing data and engage in cost-benefit analyses.
The National Climate Assessment helps us do just that. The report just released is the second volume of the two-part assessment mandated by Congress (the first volume was released in October 2017). This new report, Volume II: Impacts, Risks, and Adaptation in the United States, emphasizes how “climate change is a risk management challenge for society” and how “mitigation efforts can reduce future risks.”
The report explains:
Measuring risk encompasses both likelihoods and consequences of specific outcomes and involves judgments about what is of value, ranking of priorities, and cost–benefit analyses that incorporate the tradeoffs among climate and non-climate related options. This report characterizes specific risks across regions and sectors in an effort to help people assess the risks they face, create and implement a response plan, and monitor and evaluate the efficacy of a given action.
When asked about climate change and the report this week, President Trump told the Washington Post, “One of the problems that a lot of people like myself, we have very high levels of intelligence but we’re not necessarily such believers.”
But Trump and people like him do not need to believe or even “know” the scientific consensus on climate change to be true. They only need to recognize there is a high probability that doing nothing to mitigate and adapt to climate change will have profound consequences for the economy, infrastructure, and human health in the not-too-distant future.
If Trump holds enough trust in probabilities to decide whether to invest in a real-estate venture without “knowing” the return on investment is certain; then he should have enough trust in the recommendations made in this probability-based risk assessment (compiled by thirteen federal agencies in consultation with 300 leading scientists) to begin carbon emissions reductions. Any risk manager staring at the high probability of future losses described in this report would be negligent not to invest in carbon emissions reductions today.
