The development of improved models for studying the earth system is an ongoing major focus of the collaboration between Princeton and NOAA-GFDL. Such models are continually improving to provide greater realism and credibility to simulations of the earth system by including more components of the earth system, by including better representation of physical, chemical and biological processes, and by increasing resolution. The major components of an Earth System Model are:

1. An ocean general circulation model, including a dynamical core to represent the fundamental fluid dynamics, and parameterizations of sub-grid-scale processes, such as mesoscale and submesoscale dynamics, and mixing.
2. Models for cryospheric processes, including ice-sheets, sea-ice and icebergs.
3. An atmospheric general circulation model, including a dynamical core to represent the resolved fluid dynamics, a radiation scheme, and parameterizations of sub-grid-scale processes such as clouds, convection, and turbulent transport in the planetary boundary layer.
4. An atmospheric chemistry model for predicting important chemical tracers.
5. A land model for surface hydrology and terrestrial biogeochemical processes.
6. An ocean biogeochemistry model enabling the prediction of the carbon cycle.

For each of these components, improvements continue to be made in creating faster and more accurate dynamical cores, more physically-based parameterizations, and including more active chemical tracers, e.g., the Nitrogen cycle. A common theme of these improvements is the use of greater understanding of important climate processes, gained through a combination of observations, process modeling and theoretical analysis, to advance the global model representations.