America’s Millennials are less likely than older generations to identify with the environmental movement, according to a new Pew Research Center report out Friday. The word "environmentalist" typically conjures up images of earnest young idealists gathering petition signatures and chaining themselves to old-growth trees. But today’s study finds that older Americans are more likely to call themselves environmentalists than younger ones.

Forty-four percent of the Silent Generation – those born between 1928 and 1945 – say the word "environmentalist" describes them very well, compared to 42 percent of Boomers and Gen-Xers, and only 32 percent of Millennials. This is partly because younger adults simply don’t like labels – back in the late '90s the Gen-Xers were the cohort least likely to identify as environmentalists. But four-in-ten of them embraced this description then, compared to the third of Millennials who do so now.

More significantly, Millennials are willing to self-identify with other issues, particularly gay rights. Fifty-one percent of Millennials describe themselves as supporters of gay rights, versus only 37 percent of Gen Xers, 33 percent of Boomers, and 32 percent of the Silent Generation. This suggests that gay rights is more of a salient, self-defining issue for Millennials than protecting the environment.

This isn’t to say that they don’t care about the environment. For instance, a 2011 Pew survey found that compared to other generations, Millennials were more supportive of stricter environmental laws, more likely to attribute global warming to human activity, and more likely to favor environmentally-friendly policies like green energy development and tax incentives for hybrid vehicles.

Taken together, the two Pew surveys indicate that while Millennials are generally supportive of policies protecting the environment, they don’t identify strongly with environmentalism as a whole. This may portend future trouble for a movement that relies heavily on highly-motivated volunteers to donate time and money in support of its cause.