Atmosphere Ocean Science Colloquium
Sea ice: the next generation
Speaker: Chris Horvat, Brown
Date: Wednesday, November 11, 2020, 3:30 p.m.
The polar oceans, those covered by sea ice at least during some part of the year, cover less than 7% of Earth's surface area, yet might have the greatest pound-for-pound impact on Earth's energy budget. Consider that the rapid decline of summer/fall Arctic sea ice, overall representing an annual change in just 0.3% of Earth's surface, leads to an increase in planetary warming 25% as large as total anthropogenic greenhouse gas emissions. Yet the polar oceans are challenging to observe, describe, and model for many reasons, not least of which is their remoteness. As a consequence, I'll show that climate models remain unable to represent the loss of sea ice in any month of the year, even accounting for internal variability and differences between climate models - and exhibit wide inter-model variability in mean sea ice state.
Major changes are needed in how sea ice and the polar oceans are understood, observed and modeled. I'll discuss new observations from the ICESat-2 and CryoSat-2 altimeters of waves propagating through and fracturing sea ice, new modeling and observations of wide-spread under-ice phytoplankton blooms, and of sub-mesoscale mixed-layer variability energized by sea ice fragmentation. Together these indicate that sea-ice-covered regions are far more interesting and heterogeneous than climate models give them credit for. Along with the failure of sea ice models to capture sea ice's response to global warming, these new advances motivate the advent of a new generation of coupled sea ice models. I'll explain how we plan to do this through the Scale Aware Sea Ice Project - a new initiative with colleagues in the UK, France, and Norway, in which we are working to develop a new multi-scale sea ice model that reflects the true fractured and heterogeneous nature of sea ice and its coupling with the ocean below.