Several times in recent years, this newspaper has called attention to the hazards of a warming climate. The risks are increasing locally, nationally and globally, and the world must cut back on greenhouse gas emissions. Today, carbon dioxide, the most abundant greenhouse gas, is present in our atmosphere in concentrations of about 420 parts per million, rising a little each year. These are levels not seen since the Pliocene epoch more than 4 million years ago when sea levels were at least 20 feet higher than they are today. That kind of ocean rise is enough to inundate nearly all the world’s coastal cities.

Ocean rise is only one of the threats posed by climate change. More destructive winds, rain “bombs,” more deadly hot spells, more catastrophic wildfires – they’re all in our future if we can’t get greenhouse gases under control.