Sensitivity of the Atlantic Meridional Overturning Circulation to Model Resolution in CMIP6 HighResMIP Simulations and Implications for Future Changes

The ocean circulation in the North Atlantic is important for Northern Hemisphere climate, and hence, it is important to assess the risk of changes caused by climate change. In this work we use seven different global coupled climate models to simulate the period 1950-2050, using different horizontal grid spacings of the ocean (and atmosphere) models. We find that, when assessed against observations at 26.5°N in the Atlantic, the higher-resolution models tend to perform better, though this is not so obviously the case at higher latitudes. In the future projections to 2050, the higher-resolution models typically have a larger reduction in their ocean circulation compared to the lower-resolution models, with potential implications for climate risk and impacts.