The Most Important Number on Earth By Bill McKibben

Sooner or later, you have to draw a line. We've spent the last 20 years in the opening scenes of what historians will one day call the Global Warming Era—the preamble to the biggest drama that humans have ever staged, the overture that hints at the themes that will follow for centuries to come. But none of the notes have resolved, none of the story lines yet come into clear view. And that's largely because until recently we didn't know quite where we were. From the moment in 1988 when a nasa scientist named James Hansen told Congress that burning coal and gas and oil was warming the earth, we've struggled to absorb this one truth: The central fact of our economic lives (the ubiquitous fossil fuel that developed the developed world) is wrecking the central fact of our physical lives (the stable climate and sea level on which civilization rests). For a while, and much longer in the US than elsewhere, we battled over whether this was true. But warm year succeeded warm year and that fight began to subside. Instead, the real question became, is this a future peril, the kind of thing you take out a reasonably priced insurance policy to guard against? Or is it the oh-my-lord crisis you drop everything else to deal with? Will Hitler be happy with the Sudetenland, or is the world going to spend every cent it has, not to mention tens of millions of lives, fighting him off? Trouble, or TROUBLE? These last 12 months, we've found out.