Dr. Aixue Hu 

National Center for Atmospheric Research, USA

 

邀请人 ： 林鹏飞 研究员

 

2024年1月30日（星期二）10:00

3号楼1218会议室

 

报告摘要:

“Tipping point” is defined as a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. “Tipping element” is defined as components of the Earth system that may pass a tipping. In our climate system, multiple tipping elements have been found, such as the Atlantic Meridional Overturning Circulation (AMOC), Greenland or Antarctic Ice Sheet, boreal or tropical forest, permafrost, sea ice, etc. Here we specifically study the AMOC stability under past and future conditions. It is found that when freshwater forcing is dominant, multi-equilibrium states of this circulation (an abrupt collapse/reactivation) become possible only under simulated glacial conditions with closed Bering Strait. Under present day and future conditions, both freshwater and greenhouse gas forcings could collapse this circulation, but only greenhouse gas forcing produced a bi-stable equilibrium state comparable to abrupt climate change. Our results demonstrate that the Bering Strait status (open vs. closed) may facilitate or prohibit the existence of this circulation’s hysteresis, irrespective of the background climate conditions, but is directly related to the primary forcing.

 

报告人简介:

Dr. Aixue Hu is a Project Scientist at the National Center for Atmospheric Research. His research focuses on the variability and stability of the Atlantic Meridional Overturning Circulation (AMOC) and its impact on regional and global climates, as well as decadal and multi-decadal mode variability and the regional and global sea level changes. He has pioneered research into the influence of the Bering Strait status on AMOC stability and sea level changes, the impact of internal variability on projected sea level rise, and the effects of solar panels on global climate. He has published influential works in top journals, such as PNAS, Nature Geosciences, Nature Communications, and Nature Climate Change. Currently, he serves as the Co-chair of the Climate Variability and Change Working Group (CVCWG) within the CESM project, a member of the Scientific Steering Committee for Past Global Changes (PAGES), a member of the Ocean Knowledge Action Network (Ocean KAN) Steering Committee for Future Earth, and was previously a member of the CLIVAR Climate Dynamics Panel and co-chair of US CLIVAR AMOC task team 3.