Session: Last Millennium & Past2K
Author: Fei Liu / firstname.lastname@example.org / Nanjing University of Information Science and Technology, China
Co-author: Bin Wang, University of Hawaii at Manoa;
Jian Liu, Nanjing Normal University;
Understanding climate change caused by different external forcing is urgent for crisis management and sustainable economic development. Although previous works have demonstrated that more rainfall is generated by the natural forcing-induced global warming than by the anthropogenic greenhouse gas (GHG) forcing, it is not clear how differently the global precipitation changes in response to the global warming induced by the change of single forcing of solar radiation, volcanic activity or GHG. We address this issue using paleoclimate experiments forced by single forcing for the period of 501 to 2000 AD. The results show that the strong low-frequency variability longer than one decade can be excited by such external forcing, and that global warming can be induced by strong solar radiation, high GHG concentration or global cooling due to strong volcanic eruption. For a given temperature change, the global precipitation change is the largest under volcanic forcing, while it is the smallest under GHG forcing. The reason is that GHG forcing tends to excite stronger high-latitude warming, especially stronger Arctic amplification of global warming than the other two individual forcing does, and there is no Arctic amplification of temperature decrease under the volcanic forcing-induced global cooling. Volcanic forcing, however, causes a strong precipitation decrease in the Intertropical Convergence Zone (ITCZ) and Asian monsoon. In other words, volcanic forcing excites ITCZ and Asian monsoon amplification of precipitation decrease. It seems that a strong volcanic eruption can reduce precipitation rather than stopping the Arctic amplification of temperature increase under the GHG-induced global warming in future. The underlying mechanisms for these different climate responses are also discussed.