It’s helpful to compare where the average person’s emissions come from. Housing is the top source (around a third) and transportation is next (around a third as well). For most people, those emissions vary dramatically. Frequent flyers, especially. Because plane travel is so energy intensive, it often contributes an outsize share of one's emissions.

So even if you drive every day for a commute, flying across the country several times could swamp those emissions. So there’s no one right answer to that except to say that a few long flights equals many, many miles in a car.