Climate Models May Hide Ocean Shifts, Researchers Warn
Scientists discovered that ocean currents can undergo major changes even after climate models appear to stabilize, undermining confidence in long-term climate projections. The finding suggests current equilibrium checks are insufficient, potentially affecting the reliability of models used by governments and industries for climate planning and investment decisions.
Originaltitel: Evaluation of Quasi-Equilibrium Criteria for Coupled Climate Model Simulations
<p>We evaluate five commonly-applied criteria to validate that a climate model is in so-called “quasi-equilibrium,” using a suite of five simulations with CO<sub>2</sub> concentrations between 1× and 16× Pre-Industrial values. We find that major changes in ocean circulation can occur after common thermal equilibrium criteria are reached, such as a small Top of Atmosphere radiative flux imbalance, or weak trends in surface air temperature, sea surface temperature, and deep ocean temperature. Ocean circulation change, in turn, impact high-latitude SAT, sea ice, and the Inter-tropical Convergence Zone position. For future modeling studies and intercomparison projects aiming for an ocean in quasi-equilibrium, we suggest that time series of key meridional overturning circulation (MOC) metrics in the Atlantic, Pacific, and Southern Ocean are saved, and that MOC trends are less than 1 Sv/1000 years, and DOT trends less than 0.1°C/century for the final 1000 years of the simulations.</p>