In 2007, climate change experiments with a coupled model of the climate system were carried out at MPI-M (Mikolajewicz, U., M. Vizcaino, J. Jungclaus, and G. Schurgers (2007), Effect of ice sheet interactions in anthropogenic climate change simulations, Geophys. Res. Lett., 34, L18706, doi:10.1029/2007GL031173.). In addition to components for the atmosphere (ECHAM5 T31L19, about 400 km horizontal resolution) and ocean (MPI-OM, 330 km resolution, 40 levels), the coupled model included a dynamic model of the land biosphere (LPJ) and a thermo-mechanical model of the Antarctic and Greenland ice sheet (model SICOPOLIS, about 80 km resolution). One of the scientific objectives of the simulations was the examination of impacts of the melting Greenland ice sheet on climate, specifically on the thermohaline circulation in the North Atlantic.

The visualization below shows the response of different climate variables to a strong increase in greenhouse gas concentrations of up to four times the preindustrial value:

  • Sea ice cover in summer (medium blue) and winter (light blue)
  • In the ocean: convection depth (colored contours, color scale on the left) - a measure for the formation of deep water
  • Over land: leaf area index (LAI, color scale on the right)
  • Changes in the thickness of the Greenland ice sheet (color scale at bottom left).

 

 

The time course and the corresponding CO2 concentrations are shown in the blue box at the bottom right. Starting with model year 2000, the CO2 concentration is increased by 1% per year up to about four times the pre-industrial value. From then on it is held constant.

Due to the strong warming (not shown here), the deep convection weakens relatively quickly. Also, the sea ice cover decreases rapidly. First, sea ice only completely vanishes in summer, but later, about 200 years after the strong increase of CO2 concentration, the winter sea ice disappears as well.

The Greenland ice sheet melts - especially at its edges - as represented by the reddish coloration. This mass loss through melting is accompanied by a rise in the sea level. At the end of the experiment, this represents a sea level rise of more than 2 meters. Furthermore, the sea level rises by an additional 2 meters due to the expansion of the water body caused by heating. This yields a total sea level rise of about 4 meters.