Sometimes, it seems, threats to our future become so great that we opt to ignore them. Yet if we fail to act with the utmost urgency to slow climate change, we will invite catastrophe on all humanity.

On the northwestern edge of Los Angeles, where I grew up, the wildfires came in late summer. We lived in a new subdivision, and behind our house were the hills, golden and parched. We would hose down the wood-shingled roof as fire crews bivouacked in our street. Our neighborhood never burned, but others did. We were all living in the “wildland-urban interface,” as it is now called. More subdivisions were built, farther out, and for my family the wildfire threat receded. Tens of millions of Americans live in that fire-prone interface today—the number keeps growing—and the wildfire threat has become, for a number of political and environmental reasons, immensely more serious.