He is an ecologist and runner.
As an ecologist, he studies plant & insect communities.
As a runner, he loves to spend time outside and explore the natural world.
He does all the usual things that someone whom values the planet would do.
He recycles, takes short showers, drives as little as possible, eats organic, conserves energy, and lives modestly in a small house.
However, he flies, often for ecology.
Ecologists need to travel less or there will be little ecology left to study.
He can save a whole planet by flying less.
He can save another whole planet if he drove less and ate more local food.