The goalposts keep shifting in the debate over climate change policy. For example, it used to be called “global warming,” but now is called “climate change.” The cynic would say that this rhetorical shift was necessary, so that if and when there is another “pause” in rising global temperatures, the advocates of aggressive government action won’t be stuck in another awkward position. After all, there will never be a pause or “hiatus” in change to the global climate.

Another, more subtle example of the change in the debate is the treatment of uncertainty. It used to be that the “deniers” were the ones (allegedly) throwing out the “consensus science” of the peer-reviewed literature, and who clung to the fact that there were still aspects of the global climate system that scientists didn’t fully understand. To drive home just how immoral and dishonest these people were, supporters of government intervention referred to them as “merchants of doubt,” and compared them to scientists dragging their feet on the dangers of smoking. Why, there was even a popular book on the topic:

Merchants of Doubt
Merchants of Doubt

But again, over the years, the goalposts have shifted. As more and more skeptics called the bluff and pored over the “official” sources, we found that no, the actual peer-reviewed literature did not support what the radical alarmists were claiming.

To give just two examples: Back in 2014, I used the UN’s own summary of the climate change research to show that the popular goal of limiting global warming to 2 degrees Celsius was probably a cure worse than the disease. And then last fall, when William Nordhaus won the Nobel Memorial Prize for his pioneering work in climate change economics, I pointed out the awkward fact that his model shows that the now-fashionable goal of 1.5 degrees Celsius is so economically destructive, that it would be better for governments to do nothing rather than implement such a draconian program.

Since standard economic cost/benefit tests don’t come close to justifying the aggressive goals of the most radical activists, they have shifted the goalposts. Now they’re the ones focusing on uncertainty and the limits of our models. For example, the recently (and tragically) deceased economist Martin Weitzman was a hero to the radical interventionist camp, because he used sophisticated mathematical models to argue that economists like William Nordhaus were downplaying the risk of catastrophic climate change. Now Weitzman’s work on probability distributions is quite technical, but here is an accessible introduction he gave in a paper:

I believe that the most striking feature of the economics of climate change is that its extreme downside is nonnegligible. Deep structural uncertainty about the unknown unknowns of what might go very wrong is coupled with essentially unlimited downside liability on possible planetary damages. This is a recipe for producing what are called ‘‘fat tails’’ in the extremes of critical probability distributions.…It is difficult to judge how fat the tail of catastrophic climate change might be because it represents events that are very far outside the realm of ordinary experience. [Martin Weitzman, bold added.]

Notice the rhetorical approach Weitzman is taking. He is not saying that policymakers need to ignore the doublespeak from “deniers” and “merchants of doubt.” No, it’s Weitzman who thinks the most crucial element of the climate change debate is our doubt—namely, our “deep structural uncertainty about the unknown unknowns.” According to Weitzman, we need to act, and aggressively, because we don’t really understand the climate system very well.

For another example of this trend, it’s becoming more and more commonplace for advocates to justify aggressive government intervention as a form of “insurance.” Again, notice the pattern: You don’t need insurance for something that is going to happen. Rather, you buy insurance against events that might happen.

I have previously shown here at IER why the insurance analogy doesn’t work on its own terms—when you actually plug in the numbers, aggressive climate change measures are ludicrous “insurance policies” that nobody would buy in the context of fire insurance on a house—but my point right now is to focus on the changing rhetoric: By calling their preferred measures “insurance,” the radical interventionists now have a nonfalsifiable position. No matter what does happen, they can always say their nightmare scenarios could have happened, and so nobody can ever prove that they were being overly dramatic in their warnings.

Finally, let me cite the example of a recent study from Columbia University (and other outlets), arguing that the economic threat from climate change has thus far been understated. Here is how Matthew Klein opens up the discussion in his Barron’s review, in a piece entitled, “Is the Economic Threat of Climate Change Understated? A New Paper Says Yes”:

Betting that the future will be similar to the recent past often works well. The weather today will probably be similar to the average over the past week. The best price of a stock or a bond is probably close to wherever it last traded.

This observation is sometimes useful, but it can also be misleading. It can’t prepare you for rare events, much less events that, to your knowledge, have never happened before. [Matthew Klein, bold added.]

Yet again we see the new pattern: In order to warm the reader up to the need for aggressive government intervention to fight climate change, we have to throw out the conventional economic models and how they treat risk. Instead, we need to embrace a new approach that explicitly gives more attention to very unlikely events for which we have no empirical evidence to guide our decisions.


The goalposts have shifted in the climate change debate. Today’s “skeptics” are those who actually read the peer-reviewed studies on the likely damages from climate change, and discover that the UN’s own summaries of the research don’t support the UN’s stated goals for climate change. In contrast, the cutting edge researchers supporting aggressive government intervention have to focus the debate on what our models leave out, and what we don’t know. In other words, today’s aggressive interventionists are now playing the role of the “merchants of doubt.”

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