Applied Mathematics seminar | Jennifer Mecking, Is it possible for the Gulf Stream to Shutdown?

The answer to this question is no, as long as the sun is shining and the earth is rotating the Gulf Stream will continue to flow. However, through the addition of fresh water to the high latitude North Atlantic and/or Arctic oceans it is possible to cause the Atlantic Meridional Overturning Circulation (AMOC) to shutdown, which we refer to as the AMOC-OFF state. The AMOC is responsible for transporting heat northward in the Atlantic Ocean allowing us to experience the climate we have today.

For this work we use the high resolution, state of the art, coupled climate model HadGEM3 to generate an AMOC-OFF state. Evidence suggests that the AMOC-OFF state is relatively stable, much more than in previous generation climate models, defying the general accepted paradigm that a stable AMOC-OFF state was an artifact of ocean-only models and intermediate complexity climate models. HadGEM3's AMOC is now, for more than 150 years, in the OFF state and does not (yet) show any sign of returning to the AMOC-ON state. The AMOC-OFF state causes annual mean surface air temperatures to decrease by up to 8C in much of the Northern Hemisphere along with a longer snowy season. I will discuss climate impacts of the AMOC-OFF state and feedbacks that maintain the AMOC-OFF state.