China is responsible for about ten per cent of the global warming since the pre-industrial era, reports a paper in this week’s Nature. The study, which is the first comprehensive assessment of China’s contribution to global radiative forcing, also suggests that China’s goal of improving air quality could lead to an increased contribution to global radiative forcing.
A positive radiative forcing - here, the difference in net energy input to the climate system between now and 1750 - can be caused by changes in concentrations of greenhouse gases and aerosols. It is often assumed that rapid industrialization has increased China’s impact on the climate system, but the magnitude of the change - and the contribution of different pollutants - has remained difficult to quantify.
Bengang Li and colleagues use biogeochemical and atmospheric models, combined with a suite of observational data sets, to quantify China’s current (2010) and historical (1750 to 2010) contribution to global radiative forcing. They find that carbon dioxide from burning fossil fuels is the single biggest contributor to warming, but that methane and black carbon aerosols are also important. They show that sulfate aerosols provide a strong cooling effect, which suggests that efforts to improve air quality could have the effect of accelerating China’s contribution to radiative forcing, unless simultaneous emission reductions are put into place.