First up, get an idea of what is at stake by reading Dire Predictions: Understanding Global Warming By Michael E. Mann and Lee R. Kump. Here's a book review through Dailykos.
Also, via Time magazine: The Global Warming Survival Guide
Can one person slow global warming? Actually, yes. You—along with scientists, businesses and governments—can create paths to cut carbon emissions. Here is our guide to some of the planet's best ideas.And an informative essay adapted from a Energize America presentation at Netroots Nation.