This summer lots of Americans have been getting on planes again — and that comes with a lot of greenhouse gas emissions. For those who fly a lot, air travel typically makes up the biggest portion of their carbon footprint. So what’s an eco-conscious traveler to do?

Buying carbon emission offsets to counteract the impact of air travel is one option. But offsets may not deliver on all they promise. 

Before the pandemic, Laura Iversen in Portland, Oregon, was often jetting away somewhere for a weekend trip. 

But the climate crisis made her rethink that. She’s paid attention to the extreme wildfires and flooding recently and has lived through unprecedented temperatures this summer. During one of the recent heat waves in the Pacific Northwest, it was sometimes 100 degrees inside her house.  

“I had to put three of my four pets in the tub in cold water and wash them down, they were so hot,” Iversen said. That’s three cats and one chihuahua. 

Iversen plans on flying less in the future, but she really wants to visit her baby niece, Juliet, in Philadelphia this fall. So she’ll buy carbon offsets for her flight. 

Pay for projects that reduce emissions elsewhere

The idea behind offsets is that people or companies can offset their own greenhouse gas emissions by paying toward projects that reduce emissions somewhere else — think planting trees or new wind energy development. 

Iversen let me sit in, virtually, while she shopped online for carbon offsets for a flight from Portland to Philadelphia. One site calculated her share of that flight’s footprint: nine-tenths of a ton of carbon emissions. But on another site, it was much higher. 

“It’s saying an entirely different number for how much carbon it estimates,” Iversen said. 

Some organizations let you pick the kind of offset project you want to fund; you can choose to fund a rainforest protection project or an urban tree planting project, for example. 

This voluntary carbon offsets market is unregulated, and there’s no standard price tag for one ton of carbon emissions. The cost to offset Iversen’s flight is different on four websites, ranging from $7.73 up to $34.  

One reason for that is that there are many kinds of offset projects: paying to upgrade cookstoves in Sudan is probably a lot less expensive than, say, brand-new technology that sucks carbon emissions out of the atmosphere.  

Danny Cullenward, policy director with the research nonprofit CarbonPlan, notes the prices in the market are just not high enough to make a difference. 

Price points are a “complete joke”

“$1, or $5, or even $10 [is not] a ton … the idea that we can cheaply offset our way to carbon neutrality at the price points you see in these markets is just a complete joke,” Cullenward said. 

A European Union study from 2016 looked at a broad group of carbon offset projects and found that 85% of them were probably not making good on their promises to reduce emissions. 

Nancy Young, vice president of Environmental Affairs with the trade organization Airlines for America, believes some past criticisms of carbon offsets were justified, but standards are different now. 

“That verification and validation process that’s in place for airline carbon emissions, reductions and offsets is very solid today,” Young said. 

But it’s hard to measure the real effects of these projects, notes Barbara Haya, who studies offsets as the director of the Berkeley Carbon Trading Project at the Goldman School of Public Policy at the University of California, Berkeley. 

Take a project that pays someone not to cut down trees. 

“When you pay a landowner not to harvest their land, how do you know that they would have harvested their land?” Haya said. 

Maybe they were not planning to cut down their trees; that would mean the landowner is being paid for not doing something they weren’t necessarily going to do in the first place. 

Net-zero emission goals

Haya pointed out that offsets are especially a problem for the growing number of companies using them to hit net-zero emissions goals. 

“What scares me the most about offsets is that it creates the fiction that we don’t need to reduce our emissions and all we need to do is buy cheap credits off of the market,” Haya said. 

What would really help, Haya said, is flying and driving less, and shrinking our carbon footprint in other ways.