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A review of recent climate science findings finds that Jim Hansen's bright-line standard and timeframe for global action [1.0ºC limit on further increase in global temperature / 475 ppm cap on atmospheric carbon with <10 years for global action] is, if anything, not conservative enough. A rash of recent reports identify major climate forcings wholly unaccounted for in IPCC models -- such as a five-fold increase in methane releases from Siberian peat bogs -- that support the view of rapid, discontinuous climate change predicted by Hansen.
Energy market projections show that current climate policies will barely dent the ramp-up of fossil fuel use and emissions. U.S. Energy Information Administration (DOE) International Energy Outlook 2006 projects energy-related carbon emissions to increase by 57%, from 25,028 million metric tons in 2003 to 43,676 million metric tons in 2030. Emissions reductions attributable to national environmental policies adopted in furtherance of the Kyoto agreement reduce the EIA reference case by just 58 million metric tons (<1%). Energy market sector leader emissions projections are in the same range; Exxon-Mobil projects an increase from 28 billion to 40 billion tons in the next 25 years (43%).
An increase in carbon emissions in the range 43-57% is more than sufficient to push global temperature above the bright line, roughly between 2020-2030. When the level of atmospheric carbon passes 475 ppm on an upward trajectory, we must assume that Hansen's simple and terrible story -- rapid collapse in Greenland and Antarctic ice shelves, resulting in sea level rise too high and too fast for either civilization or most species to adapt -- will be initiated within the lifetime of our children.