The 42ndmeeting of the Sandbox Series will be held in-person and online:
To join in-person:
Please ensure you register in advance as spaces are limited in Rm 747 and only for those that have registered.
To join remotely via Webex:
Millennial variability, regime shifts, and equilibrium states of global ocean meridional overturning circulation in long climate simulations
Abstract:
The long-term response of the meridional overturning circulation (MOC) to radiative forcing is critical for regulating Earth’s climate. To investigate this response, we perform long climate simulations (up to 20,000 years) under atmospheric CO₂ concentrations ranging from 0.35× to 16× the preindustrial level. In the warming experiments, the Atlantic meridional overturning circulation (AMOC) rapidly collapses because of enhanced upper-ocean stratification in the subpolar North Atlantic. The AMOC recovers in the 2×CO₂ and 4×CO₂ experiments, but not in the 8×CO₂ and 16×CO₂ cases. In the 4×CO₂ experiment, a spontaneous activation of the Pacific MOC (PMOC) occurs about 2,500 years after the experiment begins. Several cooling experiments exhibit self-sustained millennial oscillations resembling Dansgaard–Oeschger events of the late Pleistocene, driven by interactions between salinity stratification and overturning circulation in the North Atlantic. We also observe millennial variability in the warm 2×CO₂ experiment, linked to the abyssal overturning cell and deep convection in the Ross Sea. This rich global MOC dynamics emerges only on long, multi-millennial timescales.
Schedule
11.00-12.00: Alexey Fedorov
12.00-12.30: Questions
12.30-13.30: Lunch
13.30-14.30: Round table “Ocean Dynamics Open problems”
14.30-15:00: Coffee and Tea