By Greg Ip

According to polls, the majority of Americans are worried about climate change and want their leaders to act on it. Suppose, though, you are in the minority. You think the scientific consensus is wrong, or too uncertain.

Even if you’re skeptical, you should probably still back a carbon tax. When you consider the range of things that could happen, odds are the country will still be better off.

Here’s why.

It’s an insurance policy. How certain are you that human-caused global warming is not causing irreversible harm? Let’s say 90%. That means you accept that there’s a 10% risk of serious economic damage. That’s enough to merit some sort of insurance policy. After all, attacks by unfriendly countries and terrorists are also pretty unlikely, but the U.S. still takes extensive and costly precautions against them.

Adopting a carbon tax now, especially if its revenues are used to reduce other, growth-damaging taxes, is a pretty cheap insurance policy. It is a much lighter burden on growth than command-and-control regulations or green-energy subsidies. It can also be implemented gradually so that the growth effect isn’t felt for a long time.

Indeed, a study by Resources For the Future found that a carbon tax of $45 per ton rising at 2% above inflation per year would reduce household incomes by just 0.5% to 0.8% in the year 2030 (depending on what the money is used for). That would reduce annual economic growth by a barely perceptible 0.06 percentage points per year.

By 2030, any remaining uncertainty over global warming should be dispelled. If the proof of damaging climate change has become incontrovertible, you’ll be glad action was taken. In the unlikely event the scientific consensus has been overturned, little harm done.

Something worse could come along. Since public opinion favors action on climate change, something is probably going to happen. Better that it be a carbon tax, such as the one Washington state will vote on in November, which returns the money to taxpayers, than burdensome regulations, ad-hoc bans such as of the Keystone pipeline, and subsidies for technology that may never be profitable.

Of course, some political leaders may still demand such measures. Opponents can cite the carbon tax as proof action has already been taken. And if those regulations get imposed anyway, the presence of the tax means they’ll be less harmful, because it will have already nudged the economy away from fossil fuels and toward renewables.

Other countries will act. Even if the U.S. takes no action on climate change, other countries increasingly will. That will change the sorts of products and services that sell well in their markets.

Take cars. Toyota’s Prius owes its success in no small part to the fact it was introduced in Japan, where gasoline costs roughly $4.50 per gallon. The two top-selling cars in Japan are both Prius models. If American companies are forced to design goods and services in a domestic market with a carbon tax, they’ll be better placed to compete in foreign markets that also penalize carbon content.

There are non-climate-related benefits. Even if you dispute the harm of carbon dioxide, there is no dispute that burning fossil fuels release all sorts of other pollutants: particulate matter (soot), sulfur dioxide, nitrogen oxides and mercury. While a carbon tax is not the most targeted way to reduce such pollutants, it still reduces the need for other mitigation measures.

Fossil fuels also kill people more directly: coal mines collapse, gas pipelines explode and rail cars filled with oil catch fire. Furthermore, imported oil props up unsavory regimes. Whether or not you believe carbon-dioxide emissions are harmful, a carbon tax reduces all these collateral costs.

So there you have it. Even if you’re a climate skeptic, think of a carbon tax the way you think of fire insurance. You don’t think you’ll need it, but if you’re wrong, you’ll be glad you have it.