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Methane leaks, the lesser of two climate evils?

  • Article by: JUSTIN GILLIS
  • New York Times
  • July 11, 2014 - 5:10 PM

 

Climate scientists long ago settled among themselves the question of whether human emissions of greenhouse gases are a problem, concluding that we are running some grave risks. But the field still features vigorous debate about how bad global warming will get, how quickly, and how to combat it.

One of the biggest fights involves how much effort to put into stopping leaks of methane gas into the atmosphere. The leaks could actually have a great effect on the climate that people living today will experience.

The importance of the issue rose with the release of President Obama’s new climate plan. It calls for greater use of natural gas, which consists mostly of methane. Among a few academics and on the far left of the environmental movement, cries are going up that the president is about to lock the United States into a supposed solution to climate change that will actually be worse than burning coal.

Is that claim plausible?

The basic facts are pretty clear. By far the most important greenhouse gas that humans are spewing into the atmosphere is carbon dioxide, which comes from burning fossil fuels. The second most important is methane, which is released when coal is mined, it escapes when wells are drilled for oil or natural gas, and it leaks from pipes that distribute natural gas. Certain agricultural practices also throw up a huge amount.

Pound for pound, methane is a far more potent greenhouse gas than carbon dioxide. But in stark contrast to CO2, methane breaks down quickly. Every time you flip on a light switch, causing more coal to be burned and CO2 to be released, you are slightly altering the Earth’s climate for thousands of years. Release a puff of methane, scientists say, and the climate influence will be gone in a few decades. “The methane is like a hangover that you can get over if you stop drinking,” said Dr. Raymond T. Pierrehumbert, a climate scientist at the University of Chicago. “CO2 is more like lead poisoning — it sticks around, you don’t get rid of it, and it causes irreversible harm.”

Despite that difference, billions of dollars are being spent to control methane leaks, and some people argue for spending more. Pierrehumbert is a leading voice challenging that approach. He argues, essentially, that the world has yet to mount a serious effort to control carbon dioxide, which will be vastly more harmful.

Taking the opposite view are scientists who argue that the short-term effect of methane should not be overlooked. Aggressively controlling methane, they say, would help slow the warming sharply over the coming decades. By contrast, “our success in controlling CO2 emissions is likely to make very little difference on temperature over the next 40 years,” said Drew Shindell, a scientist at NASA who is leaving for Duke University.

The larger issue is a tough one. If only a limited amount of political capital and money are going to be available to tackle global warming, that would weigh in favor of Pierrehumbert’s argument for ignoring methane leaks for the time being. Shindell agrees that methane control cannot be pursued at the expense of CO2 control.

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