April 22, 2015
For climate change, the point is we don't know the world will fall into crisis at exactly 2 degrees and not 2.1 or 1.8. But that range is certainly dangerous.
"The way I think of it is like smoking," said Katharine Hayhoe, an atmospheric scientist and director of the Climate Science Center at Texas Tech. "How many cigarettes are too many? I don't know. I have no idea. Nobody has any idea. But we do know the more cigarettes you smoke, the greater the risk."
Two degrees, then, is our most educated estimate. A way to focus attention.
It's incredibly valuable in that respect.