Speaker
Description
During the last 1 million years, Earth's climate has been paced by the glacial-interglacial cycle, characterized by alternating climate conditions, especially the appearance and disappearance of massive ice sheets in North America and Eurasia. These oscillations between warm (inter-glacial) and cold (glacial) states raise concerns about the potential existence of a `hot' state that could result from the Earth's climate trajectory under the current climate change. In our approach, this could be explained by the particular dynamical structure of the Earth climate and its different co-existing climate steady states (attractors).
To tackle this question, we construct the bifurcation diagram of the Earth climate as a function of the CO$_2$ concentration between 100 ppm and 560 ppm to cover the inter-glacial/glacial oscillations and the potential Earth's climate future trajectory. We analyze the stability range of each attractor and their tipping points. In addition, some particular tipping elements that can collapse/disappear (as the Atlantic Meridional Oceanic Circulation, the Greenland ice sheet, etc.) are detailed to determine the potential existence of hysteresis and irreversible behavior.
This analysis is performed using a newly developed coupled setup, biogeodyn-MITgcmIS, which employs the MIT general circulation model as its dynamical core, and offline couples vegetation, hydrology and ice sheets. For evaluating future climate trajectories, it is therefore important to consider the long-term adaptation of vegetation, hydrology and ice sheet dynamics over millennial time scales.
