| Autor: |
Needham, Michael R., Falter, Douglas D., Randall, David A. |
| Předmět: |
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| Zdroj: |
Geophysical Research Letters; 3/16/2024, Vol. 51 Issue 5, p1-9, 9p |
| Abstrakt: |
It has been suggested that the Atlantic meridional overturning circulation (AMOC) in many CMIP6 models is overly sensitive to anthropogenic aerosol forcing, and it has been proposed that this is due to the inclusion of aerosol indirect effects for the first time in many CMIP6 models. We analyze the AMOC response in a newly released ensemble of simulations performed with CESM2 forced by the CMIP5 input data sets (CESM2‐CMIP5). This AMOC response is then compared to the CMIP5‐generation CESM1 large ensemble (CESM1‐LE) and the CMIP6‐generation CESM2 large ensemble (CESM2‐LE). A key conclusion, only made possible by this experimental setup, is that changes in aerosol‐indirect effects cannot explain differences in AMOC response between CESM1‐LE and CESM2‐LE. Instead, we hypothesize that the difference is due to increased interannual variability of anthropogenic emissions. This forcing variability may act through a nonlinear relationship between the surface heat budget of the North Atlantic and the AMOC. Plain Language Summary: The Atlantic meridional overturning circulation (AMOC) is important for the wider climate because it transports a large amount of warm water northward away from the equator. The most recent generation of climate models disagree with the observed behavior of the AMOC over the twentieth century, and it has been suggested that this is due to the inclusion of aerosol‐cloud interactions in many of the newest models. Here we look at model simulations of the AMOC in several configurations to show that the disagreement in the past AMOC behavior is instead primarily due to changes in the inputs given to the models, rather than to changes in the models themselves. Key Points: The CESM2 Atlantic meridional overturning circulation (AMOC) response to aerosols depends on if CMIP5 or CMIP6 emissions are appliedLarge interannual variability in CMIP6 emissions appears to enhance the interannual variability of north Atlantic turbulent heat fluxesThis heat flux variability may drive a non‐linear AMOC response to aerosols [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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