Speaker
Description
The Atlantic Meridional Overturning Circulation, a crucial element of the Earths’ climate system, is projected to weaken over the course of the 21st Century which could have far reaching consequences for the occurrence of extreme weather events, sea level rise, monsoon regions and the marine ecosystem. The latest IPCC puts the likelihood of such a weakening as “very likely”. As our confidence in future climate projections depends largely on the ability to model the past climate, we take an in depth look at the difference in the 20th Century evolution of the Atlantic Meridional Overturning Circulation based on observational data (including direct observations and various proxy data) and model data from climate model ensembles. This shows that both the magnitude of the trend in the Atlantic Meridional Overturning Circulation over different time periods and often even the sign of the trend differs between observations and climate model output, with this difference becoming even greater when looking at the CMIP6 ensemble compared to CMIP5. We discuss possible reasons for this observation-model discrepancy and question what it means to have higher confidence in future projections than historical simulations.
| Topic | Future AMOC observing – outlining a roadmap |
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