Climate Change

Climate Skeptics Always Assume the Risks Are Overhyped

Maybe the doubters are right. But what if scientists have underestimated the threat?

Just looking at it feels hot.

Photographer: Jaap Arriens/nurphoto/getty images

Bret Stephens of the New York Times made a splash the other day with a column questioning the scientific consensus on climate change. Stephens didn’t cite any skeptical research papers or alternative theories -- his doubt was based purely on distrust of those who make confident predictions:

We live in a world in which data convey authority. But authority has a way of descending to certitude, and certitude begets hubris…We ought to know this by now, but we don’t…None of this is to deny climate change or the possible severity of its consequences. But ordinary citizens also have a right to be skeptical of an overweening scientism.

How far should we follow this principle of reflexive skepticism of expert consensus? Should we question whether matter is made of protons and electrons, just because scientists tell us with absolute confidence that these particles exist? How about whether the Earth is round? Should we view these findings as hubris, and withhold credence until scientists humbly acknowledge the possibility that electrons don’t exist and the world is flat? I feel like that’s not very rational.

QuickTake Climate Change

At any rate, there’s no easy, universal answer to the question of how much to trust experts. And it’s certainly true that climate change is a much harder question than the shape of the Earth, because human effects on climate are new and unprecedented and the system in question is complex. When it comes to complex phenomena like weather, economics or nutrition science, scientific consensus is always less reliable than in particle physics. So there’s always a chance that climate change is a smaller danger than people are making it out to be.

But there’s also a chance it’s worse. And here’s where Stephens and other climate change skeptics often seem to veer into irrationality -- they only acknowledge the possibility that scientists are overestimating climate change, while ignoring the very real possibility that they’re underestimating it.

A quick check shows that this danger is very real. From 1990 through 2012, for example, the United Nations’ Intergovernmental Panel on Climate Change -- which reviews and summarizes scientific findings on climate change from around the world -- consistently underestimated the amount that global temperature, carbon-dioxide concentrations and sea levels would rise. Again and again, scientists were too conservative in their climate-change predictions.

What this should demonstrate is that skepticism isn't an argument for doing less about climate change. It’s an argument for doing more. The more uncertain scientists’ predictions are, the greater the risk to our coastlines, our food productions and our natural ecosystems. Just like in investing, uncertainty is a reason to hedge risks, not to discount them.

Stephens also seems to ignore the possibility that climate change mitigation efforts might have other big benefits for our society and economy. He and other skeptics should be more critical of the assumption that switching to renewable energy would incur big economic costs.

The only way to slow or stop climate change without crashing the economy is to switch to renewable energy. Wind, hydro and nuclear would be part of the solution, but solar power, due to its rapid plunge in price, would probably be the biggest component:

Let the Sun Shine

Median price of residential solar power per watt*

Source: Berkeley Lab, Electricity Markets Policy Group

* 2015 dollars

Reducing carbon emissions would require relying on electric power for most things, which would entail large-scale deployment of energy-storage technologies like batteries, as well as upgraded electrical grids.

All that would take a massive investment. It would involve using labor, capital and resources on a huge scale. No one really knows how much it would cost, but ballpark estimates do exist. In 2014, the International Energy Agency estimated that deploying enough renewable energy to limit climate change to a reasonable level would require an investment of $44 trillion between now and 2050. That would be about 56 percent of one year of current global economic output, spread out over 32 years -- less than 1.75 percent of world gross domestic product, assuming the world economy keeps growing. For reference, global military spending is about 2.2 percent of output.

Meanwhile, the world is awash in cheap capital, natural resource prices are relatively low, and lots of people could use a job.

So it’s a big investment, but it’s not going to impoverish the human race. And cutting carbon pollution is likely to deliver benefits other than hedging against the risk of climate change. For example, replacing coal plants with solar panels would make the air a whole lot cleaner, especially in places like China and India. Shifting away from fossil fuels would weaken authoritarian petrostates like Russia and Saudi Arabia, and strengthen industrial nations like the U.S. And it’s always a good idea to replace a limited resource with one that's practically unlimited.

When you add those benefits to the reduced risk of flooded coasts and failing crops, reducing carbon emissions looks like a very attractive proposition even for a climate-science skeptic. If the world launches on a path of aggressively cutting carbon, the worst-case scenario is that we end up overpaying a bit for something we were probably eventually going to do anyway. Only if you believe very strongly that climate change is a myth or a hoax would you worry about saving a sliver of GDP by refusing to spend on alternative energy.

Skepticism of expert consensus is fine and good. But it’s important to remember that all policy decisions are made before all the facts are in. Making a big investment in alternative energy clearly looks like the best policy right now, no matter what side of the political spectrum you’re on.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

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    Noah Smith at

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    James Greiff at

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