Scientific American: Dear EarthTalk: What is the best way to measure how close we are to the dreaded "point of no return" with climate change? In other words, when do we think we will have gone too far? -- David Johnston, via EarthTalk.org
While we may not yet have reached the "point of no return'--when no amount of cutbacks on greenhouse gas emissions will save us from potentially catastrophic global warming--climate scientists warn we may be getting awfully close. Since the dawn of the Industrial Revolution a century...