Different Global Precipitation Responses to Solar, Volcanic, and Greenhouse Gas Forcings

Abstract

Understanding climate change caused by different external forcings is an urgent need for crisis management and sustainable economic development. It remains unclear how differently global precipitation changes in response to global temperature variations induced by the change of individual solar, volcanic, or greenhouse gas (GHG) forcings. We address this issue by performing three last millennium simulations under each of these individual forcings with the Community Earth System Model version 1.0. The results show that all three forcings can excite strong low-frequency variations that are longer than one decade, that is, global warming under strong solar radiation or high GHG concentration and global cooling under frequent volcanic eruptions. For a given global temperature change, the global precipitation change under volcanic forcing is larger than that under solar and GHG forcings. The reason is that the volcanic forcing induces the strongest solar irradiance change in the wet tropics. Among the three forcings we examined, the GHG forcing excites the strongest high-latitude warming, especially the Arctic amplification of global warming. There is no Arctic amplification of temperature decrease under the volcanic forcing-induced global cooling. The volcanic forcing weakens the Intertropical Convergence Zone and reduces precipitation. The results suggest that while volcanic eruptions can reduce precipitation, they do not mitigate the Arctic amplification of temperature increase under the GHG-induced warming. The underlying mechanisms for these different climate responses are also discussed.