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Projections for AR5






The final draft of the Working Group 1 (WG1) contribution to the Fifth Assessment Report  of the Intergovernmental Panel of Climate Change , is now available. GFDL has contributed to this report through publications describing its scientific research on climate change, by providing model projections to the CMIP5 archive of climate model results used by the IPCC writing teams to judge the quality of climate models and summarize their projections of future climate, and by contributing its scientific expertise to the writing and reviewing teams . The IPCC reports are an important mechanism through which GFDL research informs the public and policy makers on climate change issues. It is appropriate to speak of the IPCC as being one of the most important customers of GFDL research.

GFDL provided results from two closely related coupled atmosphere-ocean-land-sea ice models, known as CM2.0 and CM2.1, for the 4th IPCC Assessment that appeared in 2007. In the period leading up to AR5, the lab decided to create multiple branches of development starting from the CM2.1 model — a model with 200km horizontal resolution in the atmosphere and 1 degree resolution in the ocean. The five branches that contributed to AR5 are:

  1. CM3: a coupled physical climate model with a new atmospheric component of the same horizontal resolution as CM2.1 but with a comprehensive treatment of tropospheric and stratospheric chemistry as well as aerosols and cloud aerosol interactions, coupled to a modified version of the oceanic component of CM2.1 and to the new land model LM3.
  2. ESM2M/G: Earth system models (with closed carbon cycles in the oceans and on land), based on the atmospheric component of CM2.1 but with two different ocean components with different numerical algorithms (M has a vertical coordinate similar to the height z, while G uses constant density surfaces as its vertical coordinate.) Also uses LM3.
  3. HiRAM: A high resolution atmosphere/land only model (50 and 25 kilometer horizontal resolutions), used for “timeslice” simulations in which future projections for the ocean and sea ice are taken from lower resolution models and used as lower boundary conditions for this higher resolution atmospheric simulation ?optimized for hurricane simulation.
  4. CM2.1: Used with a new data assimilation system in the AR5 decadal prediction suite
  5. CM2.5: a higher resolution version of CM2.1 (50 km atmospheric resolution and ¼ degree resolution in the ocean.) for studying the impact of resolution of coupled climate dynamics

GFDL is currently in the midst of a model development effort designed to incorporate the best features of this diverse suite of models into a single comprehensive high-resolution earth system model, CM4.


Papers published in 2013 by GFDL authors analyzing the climate projections based on this set of climate models include the following highlights. Topics addressed but not covered in this short list include diverse components of the climate system such as oceanic surface waves, snow cover, anoxic regions of the ocean, and methane lifetime. A more complete list for 2012/2013 can be found here.

  • Doi, Takeshi, Gabriel A Vecchi, Anthony Rosati, and Thomas L Delworth, June 2013: Response to CO2 doubling of the Atlantic Hurricane Main Development Region in a High-Resolution Climate Model. Journal of Climate, 26(12), DOI:10.1175/JCLI-D-12-00110.1. (CM2.5)
  • Hallberg, Robert W., Alistair Adcroft, John P Dunne, John P Krasting, and Ronald J Stouffer, May 2013: Sensitivity of Twenty-First-Century Global-Mean Steric Sea Level Rise to Ocean Model Formulation. Journal of Climate, 26(9), DOI:10.1175/JCLI-D-12-00506.1. (ESM2M/G)
  • Levy II, Hiram, Larry W Horowitz, M Daniel Schwarzkopf, Yi Ming, J-C Golaz, Vaishali Naik, and V Ramaswamy, May 2013: The Roles of Aerosol Direct and Indirect Effects in Past and Future Climate Change. Journal of Geophysical Research, 118, DOI:10.1002/jgrd.50192. (CM3)
  • Winton, Michael, Stephen M Griffies, Bonita L Samuels, Jorge L Sarmiento, and Thomas L Frolicher, April 2013: Connecting Changing Ocean Circulation with Changing Climate. Journal of Climate, 26(7), DOI:10.1175/JCLI-D-12-00296.1. (ESM2M/G)
  • Yang, Xiaosong, Anthony Rosati, Shaoqing Zhang, Thomas L Delworth, Rich Gudgel, Rong Zhang, Gabriel A Vecchi, Whit G Anderson, You-Soon Chang, T DelSole, Keith W Dixon, Rym Msadek, William F Stern, Andrew T Wittenberg, and Fanrong Zeng, January 2013: A predictable AMO-like pattern in GFDL’s fully-coupled ensemble initialization and decadal forecasting system. Journal of Climate, 26(2), DOI:10.1175/JCLI-D-12-00231.1. (CM2.1)
  • Zhao, Ming, Isaac M Held, and Gabriel A Vecchi, et al., September 2013: Robust direct effect of increasing atmospheric CO2 concentration on global tropical cyclone frequency: a multi-model inter-comparison. U.S. CLIVAR Variations, 11(3), 17-23. (HiRAM)

We also provide a list of papers cited in the WGI/AR5 report itself with GFDL authors or co-authors, independent of the year of publication, organized by the chapter in which the papers are cited.

Finally, the analysis of the CMIP5 archive of the worlds? climate projections is only now gaining full momentum. The analysis of this archive, as well as the ACCMIP archive for chemistry-climate models, is often summarized in multi-authored, multi-institutional papers, A list of papers of this type with one or more GFDL co-authors is provided here.