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The Community Earth System Model (CESM) is a fully coupled, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate states.

CESM software is based on a framework, which divides the complete climate system into component models connected by a flux coupler.

The Community Atmosphere Model (CAM) is the atmosphere model component of the CESM. Information about running CAM as the atmospheric component of the CESM is found in the CESM release documentation. For information on CAM microphysics, visit the CAM Microphysics Development Group. Please see the Whole Atmosphere Community Climate Model Forum and the Climate Chemistry Forum for topic discussions specific to these capabilities of CAM.

The Whole Atmosphere Community Climate Model (WACCM) is a comprehensive numerical model, spanning the range of altitude from the Earth's surface to the thermosphere.

The goal of the Chemistry-Climate WG is to continue the development of the representation of chemical gas and aerosol species in the CESM and to further our understanding of the interactions between chemistry/aerosol and climate.

The Community Land Model (CLM) is the land model for the Community Earth System Model (CESM). It is a collaborative project between scientists in the Terrestrial Sciences Section (TSS) and the Climate and Global Dynamics Division (CGD) at the National Center for Atmospheric Research (NCAR) and the CESM Land Model and Biogeochemistry Working Groups. Other principal working groups that contribute to the CLM are the Chemistry-Climate, Paleoclimate, Climate Variability and Change, and Land Ice Working Groups.

The Land Ice Working Group (LIWG) was formed to develop and apply the ice sheet model component of CESM and to assess the role of land ice in climate change and sea-level rise.

Support of specific science objectives of the CESM and maintaining a state-of-the-art ocean component for the CESM as well as conducting related, but curiosity-driven, research leading to new contributions to the CESM community are the primary goals of the Ocean Model Working Group (OMWG). The former goals ensure that our working group, through CESM, fully contributes to science. The latter is absolutely necessary to keep the CESM at the leading edge of ocean climate models. This, of course, requires a continuous high level of effort and support. Information on the new ocean model component of the CESM can be found at http://www.cesm.ucar.edu/models/cesm1.0/pop2/.

CICE4 is the latest version of the Los Alamos Sea Ice Model, sometimes referred to as the Community Ice CodE. It is the result of a community effort to develop a portable, efficient sea ice model that can be run coupled in a global climate model or uncoupled as a stand-alone ice model. It has been released as the sea ice component of the Community Earth System Model (CESM), a fully-coupled global climate model that provides simulations of the earths past, present and future climate states. CICE4 is supported on high- and low-resolution Greenland Pole and tripole grids, which are identical to those used by the Parallel Ocean Program (POP) ocean model. The high resolution version is best suited for simulating present-day and future climate scenarios while the low resolution option is used for paleoclimate simulations and debugging.

Biogeochemistry, modeled in the CESM land model (CLM), and refers to the cycling of carbon and nitrogen through the plant / soil system and the interactions between these cycles as mediated by biological mechanisms of plants and soil heterotrophs.

The Paleoclimate Working Group contributes to the our understanding of climate change through hindcast simulations, comparing model results to data given forcings and boundary conditions (i.e. CMIP5 and PMIP3) and through sensitivity simulations to explore uncertainties in forcings. The working group is also involved in the development of modules for CESM for paleoclimate applications. Many paleoclimate modelling questions can be answered in the Paleo documentation. The Paleoclimate forum is intended for questions regarding implementation of forcings and boundary conditions specific to paleoclimate modeling.

The CESM data models perform the basic function of reading external data, modifying that data, and then sending it to the driver via standard CESM coupling interfaces. The driver and other models have no fundamental knowledge of whether another component is fully active or just a data model. In some cases, data models are prognostic and also receive and use some data sent by the driver to the data model. But in most cases, the data models are not running prognostically and have no need to receive any data from the driver.

The Community Sea Ice Model (CSIM) is a dynamic-thermodynamic model that includes a subgrid-scale ice thickness distribution. This model is closely related to the Community Ice CodE (CICE) version 3.1.

The CCSM version of the Parallel Ocean Program (POP) was released in June 2004 as part of the CCSM3.0 release. It is based upon POP Version 1.4.3, which was developed at Los Alamos National Laboratory. Support for the CCSM3.0 version of the model has expired in accordance with the CESM Support Policy.