Monday, August 11, 2008
80% by 2050
How did an 80% reduction by 2050 of 21006 levels become the holy grail for climate legislation in the US? I suspect there must have been a time when people thought it was the level needed for stabalization at 450 ppm. But US per capita CO2 output in 2006 was (roughly) 20 tons per capita. So an 80% reduction puts you at 4 tons per capita. But if you assume an equal share per capita world wide - which is the only fair formula - and base it on current population levels, you would end up at 550 ppm not 450 ppm. To get to 450 ppm you would need about 2 tons per capita which translates into a 90% reduction for the US. In the long run this is a difference that matters. But does it in the short run? I suspect that 90% seems like a lot more of a reduction than 80%. Being left with 10% is afterall half of what you are left with on an 80% reduction. In fact, if the US gets serious about a path to an 80% reduction, squeezing out another 10% is unlikely to be that hard. And if 80% goes down easier than 90% now, so be it. But we should not kid ourseleves about what is actually needed. India and China will never sign onto a lower per capita target than the US. At 4 tons per capita that means a 550 ppm world.