Laure Zanna, Courant Institute, NYU

Title: What controls the rate the ocean heat uptake in transient climate change?

Abstract: The ocean absorbs more than 90% of the anthropogenic heat released in the climate system, therefore mediating global warming on decadal to centennial timescales. The magnitude and rate of ocean heat uptake are affected by several key ocean processes such as Southern Ocean Ekman and eddy transports, North Atlantic Deep Water formation and diapycnal mixing. These processes and their response to forcing can impact global mean surface temperature by carrying heat and carbon from the surface to the ocean interior.

The current generation of climate models shows large spreads in their transient climate response, rate of ocean heat uptake and the strength of large-scale ocean circulation. Several links have been made between these different quantities but no consistent theory has yet emerged. Using a hierarchy of models, we will discuss the role of the mean ocean state versus perturbations in ocean processes in setting the rate of ocean heat uptake. We will compare our simple theory with state-of-the-art complex climate models under a range of forcing scenarios and present a set of emergent constraints for the rate of ocean heat uptake.

Bio: Laure Zanna joined NYU in September 2019 as an Associate Professor in Mathematics and Atmosphere/Ocean Science. She was previously at the University of Oxford from 2009 to 2019 as a research fellow and then as an Associate Professor in Climate Physics, and earned a PhD in Climate Dynamics as Harvard University. Her research focuses on the dynamics of the climate system. The main emphasis of her work is to study the influence of the ocean on local and global scales, through the analysis of observations and a hierarchy of numerical simulations. Recent projects include: ocean heat and carbon uptake, regional sea level rise, air-sea coupling and predictability in mid-latitudes and parametrization of ocean turbulence.