If you want to know why Denmark is the world's leader in wind power, start with a three-hour car trip from the capital Copenhagen

Even though holiday sales were down at least 2% from 2007, millions of Americans awoke Christmas morning to new computers, TVs and iPhones. (I didn't, but thanks for the pens, Mom.) Many of those gifts were replacements or upgrades, which prompts the question, What should you do with your old cell phone and other electronic equipment?

Scot case was not happy. Vice president of the environmental marketing firm TerraChoice, Case last year sent his researchers into a big-box retail store to evaluate the green advertising claims of some of the products on its shelves. The results were startling: of the 1,018 products TerraChoice surveyed, all but one failed to live up fully to their green boasts.

To understand what has happened to the earth's atmosphere--and, therefore, how our climate might change in the future--some ice-core scientists in the Arctic are training their eyes directly downward. It's an incredibly important job. It's also, as the participants in the North Greenland Eemian Ice Drilling (NEEM) project will attest, incredibly fun.

There were limits to how green Bruce Letvin was willing to go. For years, the 53-year-old anatomy professor had wanted to install solar panels on his Manhattan Beach, Calif., home. But the up-front installation costs always outweighed the benefits for the environment and his conscience. This spring, however, he managed to work out green financing with the help of solar company SunPower.

Maybe it happened the day after Hurricane Katrina or the night Al Gore won an Oscar for An Inconvenient Truth, but the first phase of the global-warming debate has ended. Even Skeptic-in-Chief George W. Bush recently convened a global-warming summit, where Condoleezza Rice told foreign diplomats that "climate change is a real problem--and human beings are contributing to it."

Flat strips of lush, submerged grass rise in terraces from the courtyard of Sidwell Friends' new middle school in Washington like rice paddies in a mountainous Chinese village. Part of a man-made wetland connected to the school's water system, the plants filter liquid waste, just as real wetlands do with rainwater.