Scientists largely agree that aggressive steps need to be taken to slow and prepare for climate change. The glaciers in Yosemite are disappearing, wildfires and superstorms are ravaging the nation, and Arctic ice continues to melt at a record-breaking pace. In his second term, free from the pressure to campaign for reelection, President Obama can seize the moment to do something about this environmental crisis. Still, aggressive steps – taxing carbon, a large-scale switch to renewables, banning coal – may not be politically feasible, especially with a partisan Congress and a fragile economy. The president has made progress: enacting strict fuel standards that will force cars to get 54.5 miles per gallon by 2025; providing incentives to double electricity from solar and wind; and creating 2 million new acres of protected wilderness. But there's still a lot of work to do. "Obama can do a million things," says Robert F. Kennedy Jr., an environmental lawyer and founder of Waterkeeper Alliance. "He can force coal to pay its true cost, end subsidies to carbon cronies, and deploy a compelling mix of moral and economic arguments." The temptation is to focus on issues that inflame the public, like the Keystone XL pipeline, but the president would do better to take a wider perspective. Keystone, for one, would pump only 830,000 barrels of oil from tar sands a day, about a third of the 2.3 million barrels of oil Canada already sends us, and a mere fraction of our heavily subsidized 19-million-barrel-a-day habit. We spoke to scientists, economists, and policy advisers, who recommended the most impactful environmental measures, ones that can be achieved over the course of the next four years. Here's their nine-point plan to protect the planet.