There’s a reason to worry if the 2nd Avenue subway goes up before the U.S. federal gov’t takes action on global warming.

Just in the past year China has overtaken the U.S. as the world’s biggest producer of CO2, according to James Wang, climate expert at the nonprofit Environmental Defense. “But, if you look at the historical picture, the U.S. has emitted, by far, the most CO2– greenhouse gases linger in the atmosphere for centuries,” Wang said.

The U.S. needs to act first on climate change. If we don’t act, then developing countries are surely not going to act, explains Wang, who expects that there will be a federal cap on CO2 in the next few years and hopes sooner rather than later.

But, actions speak louder than words, and three U.S. presidents have avoided action on global warming. Frontline examines the politics, money and bad science behind the federal impasse — and why towns and state governments, along with private industry, may be the ones to break it. GO