Earth System Modeling Experiments

Earth System Models (ESM)

Earth System Models (also called climate models, or GCM's) simulate past and future climate using computer code to build a three dimensional map of the climate system that is divided up into grid boxes. A climate model can simulate the movement of energy (heat) and matter (such as water vapor) between these grid boxes. Although a climate model can simulate weather events, it is not intended to simulate the exact weather on a given day; instead a climate model is intended to accurately represent the long-term, average weather in a given region. If you want to read more about climate models, see the climate modeling website I made earlier in graduate school.

Climate Modeling Experiments

Atlantic Ocean and the "Hosing" Experiment:

Oceans store and transport massive quantities of energy around the globe. Specifically, the Atlantic Ocean moves large amounts of heat from the equator to higher latitudes in the northern hemisphere. This movement of energy (known as the Atlantic Meridional Overturning Circulation, or AMOC) plays an important role in global climate, and the strength of the AMOC has varied significantly through time. Paleoclimate data suggest that past rapid warming and melting of ice sheets in and around Greenland may have released fresh (less dense) water into the North Atlantic, slowing and severely weakening this ocean circulation and heat transport.

In my first year of graduate school, I helped study output from a climate modeling experiment (we used the NOAA/GFDL ESM2M) in which a simulated freshwater cap in the North Atlantic severely weakened the AMOC. Our work showed that a weakening or shutdown of the AMOC and associated Atlantic ocean heat transport can cause the tropical rainfall belts over South America to shift to the south, drying out Central American and northern Amazonia. Importantly, extended droughts in the tropics can cause vegetation die off, releasing large quantities of stored carbon back into the atmosphere.