Topic: Impacts of Arctic Sea Ice on Atlantic and Pacific Climate

Speaker: Prof. Aiguo Dai, State University of New York, USA

Time: 3:30-5:00pm May 13, 2025

Venue: Meeting Room A901, IGSNRR

Brief Introduction to the speaker:

Dr. Dai is a Distinguished Professor in the Department of Atmospheric & Environmental Sciences at the University at Albany, State University of New York, USA. Dr. Dai obtained his PhD in Atmospheric Science from Columbia University in 1996, then worked at the National Center for Atmospheric Research (NCAR) in Boulder, CO, first as a postdoc and then as a Scientist until 2012, when he joined the faculty of the University at Albany.

Dr. Dai is an internationally renowned climate scientist with a focus on climate variability and change, Arctic climate, the global water cycle, hydroclimate, drought, the diurnal cycle, and climate data analysis. With more than 200 peer-reviewed publications, he has received around 70,000 citations with an H-index of 95. He is one of the world’s top 1% Highly Cited Researchers. Dr. Dai is ranked No. 2 and No. 21 in Meteorology/Atmospheric Science based on, respectively, 2019 citations and 1996-2019 total citations according to a Stanford study. He served as the Chair of the Climate Variability and Change Committee and Editor of Journal of Climate of the American Meteorological Society (AMS). He is an AGU and AMS Fellow.

Brief Introduction to the report:

To fully understand the potential impacts of the shrinking Arctic sea ice, researchers need to better understand the various roles of Arctic sea ice plays in the climate. In this talk, he will focus on how Arctic sea ice-air two-way interactions amplify multidecadal variability in the North Atlantic but dampen El Niño-Southern Oscillation (ENSO) variability in the Pacific.

Using CESM1 model simulations with and without the sea ice-air interactions and collaborated with observational data, they show that variations in cold-season sea ice concentrations (SIC) around Arctic marginal ice zones can significantly amplify multidecadal variations in surface latent and sensible fluxes from the Labrador Sea to the Nordic Seas, leading to larger variations in upper ocean density and deep water formation in these seas, thereby amplifying the amplitudes of Atlantic Multidecadal Oscillation (AMO) and the Atlantic meridional overturning circulation.

In the Pacific sector, SIC variations from the Bering Sea to Okhotsk Sea (BOS) lead to increased absorption of solar radiation due to reduced low clouds. This results in warming in the northern North Pacific Ocean, which excites an anomalous tropospheric Rossby wave propagating equatorward into the tropical Pacific to strengthen cross-equator winds and deepen the thermocline there. These mean changes dampen ENSO amplitude via weakened thermocline and zonal advective feedbacks. Thus, Arctic sea ice–air interactions affect both the mean state and variability in the tropical Pacific and imply increased ENSO amplitude but weakened AMO as Arctic sea ice and its interactions with the atmosphere diminish under global warming.