So you’re booking your flight, and just when you’re about to check out, the airline asks if you’d like to pay a little something to offset your share of the flight’s pollution. Or, maybe you’re an environmentally minded person, and you’ve heard you can buy these things called carbon offsets.

Are they worth it? Let’s explore.

Why Planes Are So Pollutive

A roundtrip flight from New York to Los Angeles emits more than 1,300 pounds (about 614 kilograms) of planet-warming carbon dioxide per passenger, according to an emissions calculator from the International Civil Aviation Organization. That’s about the amount of pollution you’d save if you swore off meat for 17 months.

Jet engines burn fossil fuels, releasing planet-warming gases into the atmosphere. They also release water vapor, which turns into long, thin clouds called contrails that trap heat instead of letting it escape to space — additional warming that isn’t typically included in a flight’s emissions, said Diane Vitry, aviation director at a clean energy advocacy organization called the European Federation for Transport and Environment.

Reducing emissions from air travel is difficult. Batteries weigh too much and provide too little power for long flights. Sustainable aviation fuel — biofuels made from things like corn, oil seeds and algae that can be mixed with jet fuel — is currently more expensive than traditional fuel and lacking sufficient supply to be in wide use.

“Aviation is the problem child,” Vitry said. “Aviation and shipping are not decarbonizing, and definitely not fast enough.”

That’s where carbon offsets come in.

What Is a Carbon Offset?

A carbon offset is a certificate or a permit to emit planet-warming gases. It’s connected to something that stores or reduces carbon emissions — for example, planting trees, or funding renewable energy.

The idea is that the program or action offsets your pollutive action. You drive a car that pollutes a certain amount, you buy a carbon offset that leads to the planting of a tree that sequesters the same amount, and bam: the pollutive action (driving) is offset (tree planting).

Read the full article about carbon offsets for flight emissions by Caleigh Wells at The Morning Call.