Progressives are well-armed with a pithy one-liner to throw in the faces of climate change skeptics: Do you believe in science?
It might be smarter, however, to ask: Do you believe in insurance?
Let's be honest: Most people who support doing something about climate change don't understand the science any better than their opponents. I spent over a year reporting on the economics of climate change, and I still don't think I can really claim a genuine expertise. Rather, when people say they believe the science, they're making a tribal statement about the sort of institutional authority to which they pledge their loyalty.
Moreover, science can only outline the general forces at play in climate change — the physics of carbon in the atmosphere, the trapping of heat, the way it all changes weather patterns. It can sketch different scenarios in broad strokes, including the worst cases, and give us some sense of the odds of each. But that's about it. The science can tell us that we're running a risk. It can't tell us how to react to that fact.
So the "reasonable" climate skeptics step in and say they believe the science. But they also think environmentalist hawks are being irresponsible and imprudent in demanding massive and rapid changes to how the world produces and consumes energy. The debate thus shifts from science to responsibility and ethics. It completely short-circuits liberals' tribal signaling of "I stand with science."
Progressives would be better off if they championed science a little bit less, and tried to provoke conservatives' thoughts with the analogy of insurance.
The whole point of insurance is that we should pay a little now in order to prepare for worst-case scenarios even if they don't ultimately come to pass. We understand that the future carries risks. Sacrificing a little now to ward them off is what responsible and ethical human beings do. It's the reckless and unethical who just let things ride in the name of enjoying more abundance in the here and now.
Insurance comes in many forms: You pay premiums so health insurance companies will some day pay for your care. You buy homeowners insurance in case disaster strikes your house. And if you ride a motorcycle, you buy "insurance" by purchasing an expensive leather jacket and helmet that will protect you in case you ever crash.
Insuring against climate change is more like the latter example: We need to spend money on a whole lot of things now — constructing solar panels and windmills, research and development of batteries, smart grids, building weatherization, electric cars, etc. — to avoid losing a whole lot more money to storms and heat waves and water shortages and sea-level rise down the road. Pinning down exactly how much that would cost is horribly tricky, but the models used by the Intergovernmental Panel on Climate Change (IPCC) generally put it at around 4.8 percent of global GDP by 2100.
But the key thing is that we make climate change less about science and more about risk management. Because once we all agree we're discussing risk management, we can discuss the potential risks more concretely.
The IPCC's models also project climate change could reduce global GDP by as much as 5 percent by 2100, assuming the world's current-but-inadequate efforts to reduce carbon emissions stay on course. Obviously, a 5 percent loss versus a 4.8 percent loss doesn't seem like much to panic over. But it's worth noting other models find considerably bigger reductions in global GDP from doing nothing — anywhere from one-fifth to two-thirds. Deeper than that, however, is the point that using losses of GDP as your metric for climate change's damage obscures more than it illuminates.
As energy and climate expert Trevor Houser once said: "Would you rather have a 1 percent tax increase on everyone in the country or kill 1 percent of the population? Because it's about the same impact [on GDP]." Point being, you can get a roughly 5 percent reduction in global GDP in ways that are morally mundane (raising everyone's taxes a hair) or morally horrifying (killing 1 percent of the global population would be about 75 million people). If the entire continent of Africa disappeared, for example, global GDP would only fall by about 5 percent. Climate change's economic effects will come through flooding cities, worse storms, droughts, disease, crop failures, and the like. And they will fall hardest on many of the world's poorest and most vulnerable regions. So most likely, letting climate change run its course is one of those ways of reducing GDP by 5 percent that would entail massive amounts of death and suffering. That changes the moral calculus profoundly. And it certainly seems like an unacceptable risk that we ought to insure against.
Climate change brings with it a 1-in-20 chance that agricultural production in the Midwest and South will drop by 70 percent over this century. That would surely mean the total economic destruction of towns, livelihoods, and ways of life. There's also a 1-in-20 chance that $701 billion worth of U.S. real estate will be underwater by 2100.
That certainly seems like an unacceptable risk that we ought to insure against. Indeed, that 1-in-20 chance is pretty close to the odds that you'll get colon cancer at some point in your life. You want to insure against that, don't you?
Once you've asked someone if they believe in insurance, it's inevitably followed by another question: Who pays for it? Or, to be more precise, who should pay for it? The answer is obvious: the wealthy. And that may be the outcome climate change skeptics want to avoid more than anything.
Editor's note: A previous version of this article mischaracterized an IPCC report. It has since been revised to address the mistake. We regret the error.