Atmospheric Chemistry and Climate Model Intercomparison Project

Atmospheric Chemistry and Climate Model Intercomparison Project
Name	Atmospheric Chemistry and Climate Model Intercomparison Project
Abbreviation	ACCMIP
Formation	2008
Headquarters	Geneva
Type	Scientific collaboration
Fields	Atmospheric chemistry, climate modeling, Earth system science
Parent organization	World Climate Research Programme

Atmospheric Chemistry and Climate Model Intercomparison Project

The Atmospheric Chemistry and Climate Model Intercomparison Project coordinated model experiments to evaluate interactions among atmospheric composition, radiative forcing, and climate. It linked multiple international World Climate Research Programme initiatives and engaged modeling groups from agencies such as National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, European Centre for Medium-Range Weather Forecasts, Met Office, and research centers including National Center for Atmospheric Research, Max Planck Institute for Chemistry, and Lawrence Berkeley National Laboratory. The project informed assessments by bodies like the Intergovernmental Panel on Climate Change and supported observational campaigns led by organizations such as National Aeronautics and Space Administration missions and the Global Atmospheric Watch.

Overview

ACCMIP organized coordinated model experiments to compare chemistry–climate interactions across coupled chemistry–climate and Earth system models. It addressed tropospheric and stratospheric composition, aerosols, ozone, and greenhouse gases, linking outputs to radiative forcing estimates used by the Intergovernmental Panel on Climate Change, World Meteorological Organization, and United Nations Environment Programme. The project produced standardized datasets to facilitate comparison with satellite missions like Terra (satellite), Aqua (satellite), Aura (satellite), and surface networks including Global Atmosphere Watch observations and campaigns such as Aerosol Robotic Network and Campaign for the Analysis of Regional Air Quality.

History and Development

ACCMIP emerged from discussions at forums including the World Climate Research Programme and workshops convened by institutions such as National Center for Atmospheric Research, European Space Agency, and International Geosphere‑Biosphere Programme. Early coordination involved modeling centers at NASA Goddard Institute for Space Studies, Pacific Northwest National Laboratory, Goddard Institute for Space Studies, Scripps Institution of Oceanography, and the University of Cambridge and was informed by studies from groups at Columbia University, Princeton University, Massachusetts Institute of Technology, California Institute of Technology, and the University of Oxford. Its timeline intersected with major assessments by the Intergovernmental Panel on Climate Change and with initiatives like the Aerosol Comparisons between Observations and Models and the Chemistry‑Climate Model Initiative.

Experimental Design and Protocols

ACCMIP defined common forcings, emissions inventories, and boundary conditions drawing on datasets produced by Energy Information Administration, International Energy Agency, and climate scenarios consistent with Representative Concentration Pathways. Protocols specified transient simulations spanning preindustrial, present, and future periods and included sensitivity runs for emissions from sectors characterized by agencies such as European Environment Agency and United States Environmental Protection Agency. Experiments adopted aerosol microphysics schemes and tropospheric chemistry mechanisms employed at centers like Max Planck Institute for Meteorology, Geophysical Fluid Dynamics Laboratory, Jet Propulsion Laboratory, and Los Alamos National Laboratory, and used sea surface temperature constraints following products from Met Office Hadley Centre and NOAA National Centers for Environmental Prediction.

Participating Models and Institutions

A broad ensemble of coupled chemistry–climate and chemistry–aerosol models participated, representing groups at National Center for Atmospheric Research, Met Office Hadley Centre, Max Planck Institute for Chemistry, Geophysical Fluid Dynamics Laboratory, European Centre for Medium-Range Weather Forecasts, NASA Goddard Institute for Space Studies, Scripps Institution of Oceanography, Laboratoire de Météorologie Dynamique, University of Reading, Potsdam Institute for Climate Impact Research, University of California, Berkeley, Columbia University, Princeton University, and national laboratories including Lawrence Berkeley National Laboratory and Pacific Northwest National Laboratory. Model intercomparisons incorporated outputs from chemical transport models maintained by teams at Harvard University, Massachusetts Institute of Technology, University of Tokyo, and Peking University.

Key Findings and Scientific Impact

ACCMIP quantified model spread in tropospheric ozone, aerosol optical depth, and short‑ and long‑lived greenhouse gas interactions, informing radiative forcing estimates used by the Intergovernmental Panel on Climate Change assessment reports. Results highlighted biases in representation of processes studied by campaigns such as IMPACT (campaign) and compared to satellite records from Aura (satellite) and CALIPSO. The ensemble influenced policy‑relevant synthesis produced by United Nations Framework Convention on Climate Change advisors and regional assessments by European Environment Agency and national agencies including United States Environmental Protection Agency and Environment and Climate Change Canada. ACCMIP outputs underpinned follow‑on model intercomparison efforts including the Coupled Model Intercomparison Project phases and the Chemistry‑Climate Model Initiative.

Challenges and Future Directions

Challenges identified by ACCMIP included uncertainty from emission inventories maintained by International Energy Agency and EDGAR, representation differences across aerosol schemes developed at Max Planck Institute for Meteorology and Geophysical Fluid Dynamics Laboratory, and limited observational constraints in polar regions measured by platforms such as Arctic Monitoring and Assessment Programme. Future directions prioritized coupling to biosphere models from groups at Carnegie Institution for Science and Woods Hole Oceanographic Institution, integration with high‑resolution regional models from ETH Zurich and Purdue University, and improved process representation informed by field campaigns including BARCA and satellite missions proposed by European Space Agency and National Aeronautics and Space Administration. Continued coordination with assessments by the Intergovernmental Panel on Climate Change, standards set by the World Meteorological Organization, and data stewardship by organizations such as National Oceanic and Atmospheric Administration remain central.

Category:Climate modeling