July 2nd, 2010
Key Findings
- We devised, from the atmospheric energy balance, a theory of the global-mean precipitation change caused by absorbing aerosols.
- It was shown that the damping effect of atmospheric heating on precipitation can outweigh the enhancing effect of surface warming, resulting in a net decrease.
- The results had important implications for interpreting the observations and global climate model simulations.
Absorbing aerosols, such as black carbon, which alter the Earth’s climate by absorbing solar radiation, may suppress precipitation to some extent, a model-supported analysis of the global-mean atmospheric energy budget coauthored by Yi Ming, V. Ramaswamy and Geeta Persad suggests.
As they heat up both the atmosphere and the surface, absorbing aerosols affect precipitation in opposite ways. When simulating with a coupled general circulation-ocean model the overall hydrological response to increased black carbon levels, the researchers found that the net effect on global-mean precipitation is slightly negative.The effect is too small to outweigh the 2-3 % increase in global precipitation per each degree of greenhouse warming. But absorbing aerosols could have a more pronounced impact on moist convection and general circulation than carbon dioxide and non-absorbing aerosols, such as sulfate, which merely scatter solar radiation, the authors suggest.
To read more: Ming et al., 2010