A decade ago most experts thought of global warming as the largest challenge civilization faced—but one that would happen relatively gradually. That cautious optimism has faded as one study after another has proved that the earth was more finely balanced than we’d understood. The climate crisis is bearing down on us much faster than most people realize. The temperature rise has started melting every frozen thing on earth. In the Arctic Ocean, white ice that reflected the sun’s rays is quickly turning into water that absorbs more of the sun’s heat. And, as the ice melts, there’s the very real chance of a catastrophic rise in sea levels.