Climate Component - Earth System Model

The Earth system component of the IGSM has been constructed to be highly flexible, modular, and computationally efficient, so as to:

  • Run large ensembles of multi-century runs, varying uncertain climate model parameters as identified by our research;
  • Include different levels of model detail in components, as appropriate for specific studies.
The integrated model and components are as close as possible to state of the art while maintaining computational efficiency.

We currently employ a hierarchy of Earth system representations within the IGSM. Our primary configurations are as follows:

  • IGSM2.2: includes a zonally-averaged model of atmospheric dynamics and chemistry, a thermodynamic sea-ice model, a land model with an ecosystem biogeochemistry model, and a mixed layer ocean model representing the processes of heat and carbon uptake. This configuration is our most computationally efficient Earth system model, and allows us to explore climate uncertainties by performing thousands of simulations.
  • IGSM2.3: as in the IGSM2.2, but with a three-dimensional (3D) model of ocean circulation, marine biology, and chemical processes that control the biogeochemical cycling of carbon, nutrients, and alkalinity. Despite the added complexity, this model is still relatively efficient, allowing on the order of hundreds of simulations on a Beowulf-class computer cluster.
In both of the configurations above, our Earth system component also includes an interactive atmospheric chemistry module, and an urban air chemistry component.


Utilizing this Earth system model of intermediate complexity facilitates the investigation of feedbacks and uncertainties between model components and with human drivers and mitigation goals. The simplified climate component enables extensive testing of these phenomena, which would not be practical in a calculation incorporating a high-resolution 3D chemistry/climate model. The Earth system model components of the IGSM2 are described in Sokolov et al., 2005 (Report 124).

In addition, we conduct supporting science to inform and improve the more computationally efficient IGSM. This work utilizes the following models:

  • A high-resolution 3D atmospheric general circulation and chemistry model based on the Community Atmospheric Model (CAM3) of the U.S. National Center for Atmospheric Research (NCAR).
  • A complex 3D marine ecosystem model that allows a self-assembling community structure (http://darwinproject.mit.edu).
  • A high-resolution 3D urban air-chemistry model to provide and test a simplified representation of urban processes in the IGSM.
  • The 3D ocean model that is used in the IGSM is continually being improved through our collaborations with scientists at the MIT Climate Modeling Initiative (CMI).
  • A 3D land system component that is developed by our collaborations with scientists at NCAR working with their Community Land Model (CLM) as well as at MBL with their advances in the Terrestrial Ecosystems Model (TEM).


The climate system component in the IGSM includes the following coupled submodels: