C20C+ Detection and Attribution Project    
About the project    

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The C20C+ Detection and Attribution Project was adopted as a core subproject of the World Climate Research Programme's International CLIVAR Climate of the 20 Century Plus (C20C+) Project at its 5th Workshop, held in Beijing in October 2010. Following trial experiments and development of required facilities, the role of the Detection and Attribution project within C20C+ was reaffirmed at the 6th Workshop, held in Melbourne in November 2013.


The Detection and Attribution project is designed to produce a large modelling data set optimised for addressing questions concerning:
  • the characterisation of historical trends and variability in the properties of damaging weather events, including uncertainties such as those encapsulated through differences across models;
  • the estimation of the degree to which the occurrence of historical and current damaging extreme weather is attributable to anthropogenic emissions, including understanding of the underlying uncertainties.
To achieve these goals, data contributed to the project is freely available for use.


The core of the project involves running large numbers of simulations of atmospheric climate models. These simulations differ only in their initial weather state, and so represent possible trajectories of the climate system under a given set of timing-evolving boundary conditions. The simulations are run under two families of scenarios:
  • The All-Hist scenario is intended to represent the evolution of the climate system over the past few decades. It is driven with observed changes in greenhouse gas concentrations, anthropogenic and natural aerosols, ozone, solar luminosity, land cover, sea surface temperatures, and sea ice conditions.
  • The Nat-Hist scenario is intended to represent the evolution that the climate system might have taken if anthropogenic emissions had never occurred. It is driven with observed changes in natural volcanic aerosols, solar luminosity, and land cover, but with fixed circa year-1850 greenhouse gas concentrations, anthropogenic aerosols, and ozone. Sea surface temperatures and sea ice concentrations vary as observed, but with an attributable anthropogenic change pattern subtracted. Because of the poor observational constraints on the details of this attributable warming pattern, multiple patterns and amplitudes will be investigated.

Beyond the atmosphere

While this project centres around the use of dynamical atmosphere-land models of the climate system, it is hoped that coupled models, regional dynamical models, statistical downscaling models, and a variety of "impacts" models will also be run under the conditions described above or driven with the output described above. Output from such simulations is invited for publication on the data portal.


  Project management

  • The project is coordinated by the CASCADE Scientific Focus Area at Lawrence Berkeley National Laboratory, U.S.A.
  • Data portal services are provided by the National Energy Research Scientific Computing Center, U.S.A., and by the National Oceanic and Atmospheric Administration's Earth System Research Laboartory, U.S.A.
  • Scientific Steering Committee: Dáithí Stone, Nikos Christidis, Chris Folland, Sarah Perkins, Judith Perlwitz, Hideo Shiogama, Michael Wehner, Piotr Wolski
  • Infrastructure Steering Committee: Harinarayan Krishnan, Shreyas Cholia, Dann Mitchell, Don Murray, Dáithí Stone, Michael Wehner


  • The ARC Centre of Excellence for Climate System Science, Australia
  • The CASCADE Scientific Focus Area, Lawrence Berkeley National Laboratory, U.S.A.
  • The Climate Systems Analysis Group, University of Cape Town, South Africa
  • The Met Office Hadley Centre, U.K.
  • The Model for Interdisciplinary Research on Climate (MIROC) consortium, Japan
    • AORI (Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan)
    • NIES (National Institute for Environmental Studies, Ibaraki, Japan)
    • JAMSTEC (Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan)
  • The Physical Sciences Division, Earth System Research Laboartory, National Oceanic and Atmospheric Administration, U.S.A.

    • FUNDING •

  Coordination of and contributions to this project have been funded by:

  • Biological and Environmental Research, Office of Science, US Department of Energy, U.S.A.
    • Project management
    • Data portal
    • Simulations of CAM5.1-0.25degree, CAM5.1-1degree, and CAM5.1-2degree by LBNL
  • The Joint DECC/DEFRA Met Office Hadley Centre Climate Programme (GA01101), U.K.
    • Simulations of HadGEM3-A by MOHC
  • The EUCLEIA project funded under the European Union's Seventh Framework Programme [FP7/2007-2013] under Grant Agreement No. 607085
    • Simulations of HadGEM3-A by MOHC
  • Microsoft Research
    • Project planning
    • Simulations of HadAM3P-N96 by UCT-CSAG
  • Program for Risk Information on Climate Change (SOUSEI program) from the Ministry of Education, Culture, Sports, Science and Technology of Japan
    • Simulations of MIROC5 by MIROC
  • The Water Research Commission, South Africa
    • Simulations of HadAM3P-N96 by UCT-CSAG

Maintained by: dstone@lbl.gov
Last updated: 29 July 2016

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