By the time we get proof of climate change, it will be too late to reverse course

U.S. foot-dragging fuels global warming
By Elizabeth Kolbert

The climate system is highly inertial; it takes several decades for changes already set in motion to become apparent. Scientists probably won't be able to determine just what level of greenhouse gases will trigger, say, the melting of the Greenland Ice Sheet until that level has been exceeded. But as anyone who has ever tried to push a stalled car can attest, systems that are hard to get moving also tend to be hard to stop. Although it sounds reasonable to argue that we ought to wait for certainty before taking action, if we do, effective action almost certainly will become impossible. Once we know for sure that the ice sheet is in danger of disappearing, it will be too late to reverse the process.more....