Hey Mr. Green,

Last fall, when a student asked what he could do for the environment at college, you said: (1) don't bring a car, (2) take fewer trips home, (3) don't use a mini-fridge, and (4) get your school to ban cars on campus. What's the word this year? --Debra in Springfield, Massachusetts

First, get outside, and take your friends with you. Young people with direct experience of nature are far more likely to see themselves as strong environmentalists, a 2011 Nature Conservancy poll revealed. Sierra Club founder John Muir would agree. "Come to the woods," he exhorted, although today he'd have to add, "And when you do, quit poking at your smartphone." Muir also recommended that city dwellers "lie down among the pines," but since the survey notes that fear of cold, heat, and bugs are the main reasons youths shun the outdoors, don't forget the bug repellent.

Second, take an environmental history class. Learning about the immense progress that's been made in protecting Earth can cure you from feeling overwhelmed by the threats our planet still faces. Back in my college days, we had no environmental smarts. I stomped through the University of Wisconsin-Madison Arboretum without the slightest idea that the great environmentalist Aldo Leopold was one of its creators.

Finally, hook up with a student environmental organization. My favorites this year are those campaigning to force schools to divest their endowments from fossil fuel companies and to sock away their loot in clean, sustainable energy like wind and solar instead.