Can emerging technology defeat global warming? With more than $30 billion earmarked for “green energy,” President Obama’s stimulus package marks the first serious step by a U.S. administration to tackle the threat of global warming. But as the pace of innovation slackens in the crumbling economy and the public worries more about jobs than the future of the planet, is it all a case of too little, too late? NOVA focuses on the latest and greatest innovations that include everything from artificial trees to cleaner coal, nuclear energy and wildly ambitious — and risky — schemes to re-engineer the entire climate system. Can our technology, which helped create this problem, now solve it?