Are Flight Offsets Worth It?

Q: Should I buy offsets to cover my air travel?

In recent years, many airlines have phased out the little box encouraging you to “offset your flight’s emissions!” on their checkout pages. Perhaps because so few customers took advantage of them, or perhaps because research has shown that many offset projects are ineffective or worse.

But last we checked, people are still flying. A lot. And the planet is still warming. A lot. So you may still be wondering: Should I offset my air travel? If so, how?

What are offsets, exactly?

A carbon offset is a credit that you can buy to make up for your emissions. So if you fly from New York to San Francisco, releasing around 1,000 pounds of carbon dioxide into the atmosphere, you can purchase an offset, funding a project that will remove or store that same amount of carbon dioxide elsewhere, often by planting or preserving trees.

At least that’s the idea. But many scientists object to the principle, on the grounds that we need to sharply reduce emissions, not just try to cancel them out.

“Offsetting is a misnomer,” said Barbara Haya, director of the Berkeley Carbon Trading Project at the University of California, Berkeley. “It creates a fiction that you can fly and emit greenhouse gasses and just pay for these cheap credits and it erases your impact.”

Last year, an estimated $1.7 billion of carbon credits were issued worldwide, according to an analysis from the global accounting firm KPMG.

OK. But do they work?

Companies are working on ways to improve the credibility of carbon credits. But Dr. Haya has been studying offsets for more than 20 years and so far, she said, the results have been grim. “Most credits don’t represent the amount of emissions reductions that they claim,” she said. Others have had no measurable climate benefit at all.

That’s because measuring the carbon captured by, say, planting a new tree is hard. Would that tree have been planted anyway? What happens if that tree later burns in a wildfire?

John Sterman, a professor at the MIT Sloan School of Management and director of the MIT Climate Pathways Project, compared carbon credits to the magical healing elixirs of the Old West. “I could put anything into that bottle. And it isn’t just that it might not work — it could be downright harmful. That’s where we’re at with carbon offsets,” he said. “They’re fooling people.”