Last Saturday, I enjoyed a 3.5-mile walk from a friend's apartment in San Francisco to the 11th annual Green Festival at the San Francisco Concourse Exhibition Center. Billed as "the nation's premier sustainability event," the Green Festival is an extravaganza of organic food, green building, urban farming, solar energy, green jobs, electric cars and sustainable clothing.

The Green Festival is a joint project of two nonprofits, Green America and Global Exchange.

We arrived early, both to beat the crowds flocking to the 350 exhibits and to hear Kevin Danaher, founder of Global Exchange, laud the "new triple bottom-line economy." Danaher said this new economy is developing all over the world "from the grassroots up," spurred into action by the chaos created by climate change.