On the day that Laurie David meets the Perez family of San Clemente, California, she is distressed by two news items: The Chicago marathon was halted after just a few hours due to abnormal heat that precipitated one death and several hundred injuries. And the opening of the skating rink at Rockefeller Center in New York City was marred by record-high temperatures, with pooling water instead of a frozen surface.

In the past, such alarm bells would have gone unnoticed by the Perezes: Debbie and Mark, both 37 and former teachers (Mark now works for a nonprofit organization called the Grove Center that supports church-based art), and their children, Billy, 11; Mary, 10; Delaney, 8; and Teddy, 6. But Laurie is helping them see how they are connected to that overheated marathon and melting ice rink. "We're all contributing to this problem," she says, "every day when you turn on a light or drink from a plastic water bottle. There are things the government has to do, but individual citizens also need to be part of the solution."

Sitting at the kitchen table of the family's split-level house, Laurie looks up at the recessed fixtures in the ceiling with more than a dozen lightbulbs. "To me, they're really heat bulbs," she says. Compact fluorescent lightbulbs (CFLs) use only a quarter of the energy that incandescent ones do. Australia and Canada have already voted to ban the use of incandescent bulbs by 2009 and 2012, respectively. If every American family substituted five CFLs for incandescent, it would be equivalent to taking eight million cars off the road for a year. They cost a little more up front, but they last up to ten times longer.

Debbie has prepared a typical school lunch, packed in a paper sack. "This will be used for one day, and then it's going in the garbage," says Laurie, "but this"—pointing out her own daughter's metal lunch box—"will be used for five years. When you see paper, think of a tree." According to the NRDC, Americans throw away enough paper every year to build a 12-foot-high wall stretching from New York to California. Every two seconds, somewhere in the world, a forest area the size of a football field is destroyed—all for things like paper towels, napkins, printer paper—and the loss of those trees is disastrous for the environment. Trees absorb carbon dioxide and convert it into oxygen. During its lifetime, a single tree can absorb the amount of CO2 released by the average car that's been driven 4,000 miles. "This is a petroleum product," says Laurie with obvious distaste, pointing to a one-shot water bottle. "It's made from oil. It's shipped on a truck spewing fumes. And two and a half million plastic bottles are thrown away every hour." Inside the "greener" lunch box are reusable containers for sandwiches, snacks, and drinks, made of metal or plastic. The family agrees to start questioning the products they buy: How far has this traveled to get here, and how many resources does it require? The oldest child, Billy, is the most aware and concerned about environmental issues. He shows Laurie a bag inside his closet where he keeps bottles for recycling, but she encourages him to expand his horizons. By the next day, he has already spoken to his principal about setting up collection bins at school.