It might seem tricky to chop down trees with one hand and sell climate absolution with the other, but the dubious math of carbon offsets makes it possible, at least for now.

Trees drink up carbon dioxide, the stuff that is warming the planet to dangerous levels. And aside from Uncle Sam, nobody in America owns as many trees as Seattle’s Weyerhaeuser, the biggest U.S. logger. Long a bete noire of environmentalists, the company is now using its 10.6 million acres of forest to declare it has so much green credit that it can sell some to other companies, the Wall Street Journal recently reported.

Weyerhaeuser claims its forests absorb 17 million metric tons of carbon a year. Its lumber and other products could freeze an additional 18 million metric tons in place for years or decades. This more than makes up for the 7.4 million metric tons of carbon its logging and other activities emit every year, by Weyerhaeuser’s estimation.