After 2000-era plateau, global methane levels hitting new highs

When it comes to global warming, carbon dioxide is the 800-pound gorilla: it’s the most abundant of the long-lived greenhouse gases that human activities generate. But ounce for ounce, methane (CH4) traps more heat, and it accounts for about 20% of the greenhouse gases produced by human activities. Strangely, though, global methane levels “flat lined” from 1999 to 2006. Read more.