Today's environmentalism has been called a 'Third Wave.' Unlike the conservation ethic of the early 1900s, or the calls for anti-pollution regulation and the mass nostalgia for a more agrarian past in the 1970s, we are now looking at a fully globalized world, in which the decline of one nation would send shockwaves through the rest of the world, due to our linked economies, limited natural resources and shared climate.

Therefore, says Lester Brown, author of Plan B 3.0: Mobilizing to Save Civilization, "Sustainable development is not a sexy term, but a sound concept. You hear a lot about a 'more sustainable this,' or a 'less sustainable that.' But the reality is, we're sustainable or we're not. The only way to avoid decline and collapse is a sustainable economy--a sustainable civilization."

The idea was met with cheers from the audience, a group 1,700 strong from universities and colleges all over the country, most of whom have spent years if not decades trying to make their colleges greener, and their students prepared for a world of rapidly shifting priorities and problems.

In fact, Brown went farther than most, calling for emissions reductions of 80% by 2020, a far more ambitious goal than any politician or even most academics have dared. He claims that actions this drastic might be the only way to save Asian glaciers (which provide the irrigation for vast sectors of the world's grain market) and the Greenland ice sheet. In this new environmentalism, action is no longer just about saving polar bears, but about preserving our own global society.

The question of necessity is no longer on the table. And judging by the enthusiasm of the audience, the question of "how," at least when it comes to higher education, will be the meat of the next two days.

We are recapping AASHE: Sustainability on Campus and Beyond as it happens. If you were at the sessions we're covering, weigh in with your comments below. Or see others' blogs, photos and Twitter updates on the AASHE live page.