Abstract
“In this seminar, I will explore recent advancements in our understanding of the ocean’s role in the climate system, with a particular focus on the Atlantic Meridional Overturning Circulation (AMOC) and its implications for future climate change. Climate models project a decline in AMOC strength due to increased ocean stratification, but its relative impact compared to greenhouse gas-induced changes remains unclear. I will describe our recent work addressing this issue, in which we have both examined climate model simulations in the Coupled Model Intercomparison Project (CMIP) archive, and also carried out idealized targeted experiments with a state-of-the-art global climate model (EC-Earth3). Specifically, using EC-Earth3 we compare an abrupt 4xCO2 simulation with an identical one, except we artificially fix the AMOC strength at preindustrial levels. With this design, we can formally attribute differences in climate change impacts between these two experiments to the AMOC decline. In addition, we quantify the state-dependence of AMOC impacts by comparing the aforementioned experiments with a preindustrial simulation in which we artificially reduce the AMOC strength using the more classical “water hosing” approach.  Finally, we interpret these results in the context of existing CMIP simulations. We find that an AMOC decline leads to mean climate changes, including global cooling, widespread drying in the Northern Hemisphere and a southward shift of the ITCZ. We also find an increased frequency of wintertime NAO+ and more extreme precipitation events in northwestern Europe, despite the overall drying. However, our findings demonstrate that AMOC decline impacts are state-dependent, thus understanding AMOC impacts on future climate change requires targeted model experiments. Join me as we delve into the intricate coupling between the Atlantic Ocean and the atmosphere, which influences the jet-stream, weather patterns, and precipitation, and discover the crucial role of the ocean in our evolving climate.”

BIO: Dr. Katinka Bellomo is a climate scientist at Politecnico di Torino’s Department of Environment, Land, and Infrastructure Engineering, and specializes in unraveling the intricate connections between air and sea in shaping climate variability and change. Employing a blend of numerical models, theory, and observations, she investigates mechanisms that drive large-scale atmospheric impacts on regional weather patterns. Holding a Ph.D. in Meteorology and Physical Oceanography from the University of Miami (2015), Dr. Bellomo previously conducted postdoctoral research at Columbia University and the Italian National Research Council, cultivating a deep understanding of climate dynamics.