Carbon dioxide and climate change - a warning.

An essay by Bill McKibben quoting NASA's Jim Hansen's et al's paper in Science magazine. The abstract attached to it argued with strong language for a scientific paper -- "if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm." Hansen cites six irreversible tipping points -- massive sea level rise and huge changes in rainfall patterns, among them -- that we'll pass if we don't get back down to 350 soon. Key words: carbon dioxide, global warming, social implications.