This year Thom Hawkins is missing his fourth family Thanksgiving back home in Minnesota, by choice.
The 82-year-old lives in Glendale, Calif., and hasn't visited his extended family of nieces, nephews, and cousins since September 2016. That's when he decided he couldn't fly anymore because of environmental concerns. Ever since, he has missed weddings, birthdays, graduations, and expects to miss funerals.
"On the last trip there I felt guilty if you want to know the truth," Hawkins says. "I [had] become very aware of climate change... probably hyper-aware, more than most people that I know."
He's even told his family to no longer fly to California to visit him, as he doesn't want them to contribute to climate change on his behalf. Hawkins is a part of a small but growing number of people who are choosing not to fly, or to fly less.
Comparing flight emissions to car emissions can seem confusing since cars and other land vehicles produce the overwhelming majority of transportation emissions. Flights account for just about 2.5 percent of global carbon emissions, according to The International Council on Clean Transportation.
"But the problem is that the rates [of emissions] are rising very rapidly, and currently we don't have a technological substitute that's carbon-free," says Shahzeen Attari, of the O'Neill School of Public and Environmental Affairs at Indiana University Bloomington. The number of airline passengers is projected to double in less than two decades.
Attari has found that if there were a carbon tax imposed on CO2 emissions per ton, people would change their transportation behavior.
"People would move with their pocketbooks," she says. "They would change what they're consuming based on what the prices are."