Mitigators

Reducing the production of greenhouse gases is receiving much study. Carnegie Mellon professor Jay Apt (Why Climate is Changing and What We Can Do About It.pdf) has completed an extensive study of the electrical industry which produces more CO2 than any other sector. This table shows an estimate of the economic efficiency of various technologies to reduce CO2 emissions. The cheapest method is to simply use less energy, although some would argue that there are hidden costs. The surprise is how poorly solar power looks.

Apt observes "The US spent 1.5 – 2 % of GDP on air cleanup in the 1970’s and 1980’s. Best estimates for US electric sector carbon control are 0.2 – 0.6% of GDP. The IPCC global average GDP reduction in the year 2050 to stabilize at twice pre-industrial levels of CO2 is in the range of 0.1 to 1.8 % of GDP, with most models 0.4 – 0.9% of GDP." 

Another analysis identifies fifteen changes each of which could prevent 1 billion tonnes a year worth of carbon emissions, e.g. replacing 1400 coal electric plants with natural gas-powered facilities. Any seven of these measures would be enough to stabilize the CO2 level.