Community Earth System Model

Community Earth System Model
Name	Community Earth System Model
Developer	National Center for Atmospheric Research
Released	0 2010
Genre	Earth system model
License	Open source

Community Earth System Model. The Community Earth System Model is a comprehensive, open-source software framework designed for simulating the Earth's past, present, and future climate. Developed primarily by the National Center for Atmospheric Research with broad community collaboration, it integrates separate models of the atmosphere, ocean, land, and sea ice into a fully coupled system. This allows researchers to study complex interactions and feedbacks within the Earth's climate system, making it a pivotal tool for major assessments like those by the Intergovernmental Panel on Climate Change.

Overview

The model represents a state-of-the-art tool for understanding the dynamics of the global climate system, encompassing physical, chemical, and biological processes. It is widely used for projecting climate change scenarios, investigating paleoclimate conditions, and studying phenomena like El Niño–Southern Oscillation. By coupling components such as an atmospheric general circulation model with a dynamic vegetation model, it can simulate feedbacks between, for instance, Amazon rainforest deforestation and global atmospheric circulation. Its development and application are central to research at institutions like the University Corporation for Atmospheric Research and the Lawrence Livermore National Laboratory.

Model components

The framework comprises several interacting component models. The atmosphere is typically simulated by the Community Atmosphere Model, which includes representations of aerosols and atmospheric chemistry. The ocean component is handled by the Parallel Ocean Program, modeling ocean currents and biogeochemistry. Land surface processes, including hydrology and vegetation dynamics, are managed by the Community Land Model. The sea ice component, the Los Alamos Sea Ice Model, simulates ice formation and movement. These components are coupled through a flux coupler, a software layer that facilitates the exchange of energy and mass, developed as part of the Earth System Modeling Framework.

Development and history

The model evolved from its predecessor, the Community Climate System Model, with its first official release occurring in 2010. Its development is steered by a governing board and working groups involving scientists from the National Science Foundation, the Department of Energy, and NASA. Key historical milestones include the integration of active biogeochemical cycles and the inclusion of a dynamic global vegetation model. The project has been influenced by earlier modeling efforts like those at the Geophysical Fluid Dynamics Laboratory and benefits from international collaborations, including those with the Max Planck Institute for Meteorology.

Applications and research

Researchers employ the model for a vast array of scientific investigations. It is fundamental for creating future climate projections used in reports by the Intergovernmental Panel on Climate Change and for studying specific events like the Paleocene–Eocene Thermal Maximum. Studies have examined the impact of Arctic sea ice decline on mid-latitude weather patterns and the role of the Atlantic meridional overturning circulation in climate stability. Its applications extend to assessing climate impacts on agriculture, water resources, and ecosystems, supporting policy-relevant research for agencies like the Environmental Protection Agency.

Model versions and releases

The model has seen several major version releases, each introducing significant scientific and computational advancements. Notable versions include CESM1.0, CESM2, and the subsequent CESM2.1, which featured improved representations of cloud microphysics and land-atmosphere interactions. Each release is supported by extensive documentation and idealized test cases. Development follows a rigorous process managed through repositories like GitHub, with version history reflecting contributions from a global community of developers at institutions such as the University of Texas at Austin and the Chinese Academy of Sciences.

Computational requirements and infrastructure

Running the model demands immense computational resources, typically requiring high-performance computing systems like those at the Oak Ridge National Laboratory or the National Energy Research Scientific Computing Center. Simulations can consume millions of core-hours on supercomputers such as Summit (supercomputer) or Frontier (supercomputer). The code is optimized for parallel processing architectures and relies on infrastructure like the ESMValTool for model evaluation. Data output is managed using standards like NetCDF and is often stored and distributed through portals like the Earth System Grid Federation.

Category:Climate modeling Category:Atmospheric science Category:Scientific simulation software