New York Times: For hundreds of thousands of years preceding the industrial revolution, the concentration of the greenhouse gas carbon dioxide in the atmosphere didnt exceed 280 parts per million. Now it is poised to pass 400 parts per million, thanks to the burst of fossil fuel combustion and forest clearing thats accompanied humanitys recent growth spurt. That shift was noticed thanks to decades of work by Charles David Keeling of the Scripps Institution of Oceanography and more recently his son Ralph. (Keelings...