Earlier this month, in New York City, 350.org — the organization most associated with the campaign against Keystone XL — nearly filled the 2,090-seat opera house at the Brooklyn Academy of Music for headliners Bill McKibben and Naomi Klein to talk about climate change. That many people listening to a couple of nonfiction writers discuss an environmental problem is an impressive feat. The audience cheered loudly throughout and you could feel the political power in the room.

At one point, McKibben put on the screen above the stage a list of major sources of fossil fuels that must stay unreleased if we are to keep below 2 degrees Celsius of warming and avert the most catastrophic effects of climate change. Almost all of the examples, such as a massive coal deposit in Australia, were abroad. But there was one in the U.S.: federally owned deposits of oil, gas, and coal offshore and on public land.

You could say that was a hint about what will succeed the fight over Keystone as the next major grassroots anti–climate change effort: calling for a presidential ban on extracting fossil fuels offshore and on federal land. “The public lands stuff is emerging as a big focus for all of the groups,” says Karthik Ganapathy, a spokesperson for 350.org.