A recent study published in the Proceedings of the National Academy of Sciences states that despite the increase in greenhouse gas emissions from 1998 to 2008, global surfaces temperatures have leveled off. The researchers, led by Robert Kaufman, a professor at Boston University, believe that global surface temperatures have leveled off over this time due to the increase in sulfur pollution, particularly in China. Sulfur pollution is known for having a cooling effect. With the increase in production of coal-fired power plants in China from 2002 to 2006, sulfur pollution has also increased to the point where the cooling effect appears to have offset the impact the increase in greenhouse gas emissions would have on surface temperature, researchers believe.
Researchers warn that as China installs scrubbers on the coal fired power stations, the sulfur pollution will be reduced and the real impacts of the greenhouse gas emissions will be seen. Kaufman said, “If anything, the paper suggests that reductions in carbon emissions will be more important as China installs scrubbers [on its coal-fired power stations], which reduce sulfur emissions. This, and solar insolation increasing as part of the normal solar cycle, [will mean] temperature is likely to increase faster.”