TerraChoice has found that the amount of advertising of green claims is on the rise.

Looking at 18,000 ads in recent issues of Time, Fortune, National Geographic, Sports Illustrated and Vanity Fair, TerraChoice found that more than 10 percent of all ads in 2008 made some sort of “green” claim. That’s up from about 3 percent in 2006.

The research was previewed in TerraChoice’s newest report, “The Seven Sins of Greenwashing: Environmental Claims in Consumer Markets.”