Time to confront climate-change risk

THE ISSUE: We routinely spend money and endure inconvenience to protect ourselves from catastrophic risk. Developed nations should not demand absolute certainty on global warming before taking steps to protect against it.

You’re having chest pains.

Statistically, you know it’s probably nothing. A touch of heartburn from last night’s burrito, possibly. Maybe you try antacids. Maybe you try to wait it out. But at some point, you go to the doctor.

The point at which you go to the doctor is before the point at which you are certain you are having, or are about to have, a heart attack. Indeed, the level of certainty that will prompt a doctor’s visit is far lower than with symptoms suggestive of less-serious ailments.

This is because you are weighing risks.

Going to the doctor is expensive and inconvenient, and if the burrito is the culprit you’ll regret the decision. You go anyway, even in the absence of certainty, because the stakes are high. Failing to act has a slight chance of resulting in catastrophe. The expense, while significant, pales compared to a heart attack.

This is roughly the situation that confronts all humans when it comes to global warming.

The physics behind global warming are hard to argue.

Most energy from the sun passes through the atmosphere without being absorbed. It does not convert to thermal radiation until it hits the Earth’s surface. While carbon dioxide and other greenhouse gases do not block most of the sun’s energy as it enters the atmosphere, it does reflect the thermal radiation, or heat, that radiates from the sun-warmed Earth.

There is no question that human activity since the Industrial Revolution has resulted in ever-increasing emissions of carbon dioxide and other greenhouse gases. Other things being equal, therefore, scientists would expect temperatures to be rising.

Other things are not equal, however, which means there is room for error. The climate is enormously complex, and includes factors that offset the expected planetary warming. The temperature data that would demonstrate global warming is notoriously difficult to compile, since historical records are less accurate than current ones.

That said, we are beyond the stage of fleeting heartburn. Ocean levels are rising and glaciers are melting. The data is complex, but almost all climate scientists believe human activity is raising global temperatures.

If they are correct, the consequences would be catastrophic. Relatively small changes in the ocean level would displace millions of people. Deserts would increase in size, and food would become scarce. Weather patterns would change, resulting in more violent storms.

We do not typically demand absolute certainty before hedging our bets. We buy security systems despite recognizing the odds of a break-in are low. Investors may be convinced a stock is going to increase in value, but they spend money to protect against the risk of a drop in value. We buy fire insurance even though we don’t expect a fire.

We go to the doctor for chest pain, even though we suspect it’s nothing serious.

The only way to protect against the risk of global warming is through governmental action.

That may mean aggressive carbon taxes or regulatory action.

Both are expensive.

As evidence mounts that global warming is a real threat, however, it is increasingly reckless to demand absolute certainty before taking action.

We’re dealing not with fleeting chest pain, but with persistent chest pain and left arm pain.

There is enough evidence of a coming disaster that we need to take steps to limit the risk.

(Published May 19, 2015)

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