Environmental Science and Engineering Seminar

The polar regions, as integral parts of the Earth's climate system, are both a driver and a sensitive indicator of climate change. In recent decades, the Antarctic and Greenland ice sheets and shelves have been losing net mass to the ocean at an accelerating rate. Since 2016, there has been a marked decrease in Antarctic sea ice, reaching an unprecedented low in 2023. In this talk, I will first present the critical importance of Antarctic meltwater in setting the abyssal ocean overturning in the future. Rapid melting freshens the ocean surface and strengthens the stratification in regions where dense water is formed and sinks to the bottom, and could thereby change the ventilation rate of the global abyssal ocean. Second, I will contrast the mechanisms for the distinct climate responses initiated from Greenland and Antarctic meltwater release. Finally, I will discuss the seasonal and decadal variability of Antarctic sea ice driven by the Southern Annular Mode. I use what I have learned about decadal modulation to speculate on what might have caused the dramatic decline in Antarctic sea ice observed in recent years.