CMIP6 logo-Contributed by Greg Flato

Perhaps one of the most widely-cited activities of the WCRP is the series of Coupled Model Intercomparison Projects organized by the Working Group on Coupled Modelling (WGCM). The 5th version (CMIP5) was a very ambitious effort that provided coordinated global climate model simulations including, idealized, preindustrial, transient historical, decadal predictions, and longer-term future projections under different forcing scenarios. Results from these simulations served as the basis for much of the material in Chapters 9 through 14 of the Working Group 1 contribution to the IPCC 5th Assessment Report (AR5), as well as the new Atlas of Global and Regional Climate Projections (Annex 1 of the AR5). CMIP5 model output continues to be used extensively and can be accessed via the CMIP5 Data Portal based upon the ‘Earth System Grid Federation’. At the time of writing, there were 785 publications that cited CMIP5 model output.
The 6th version of this (CMIP6) is currently being planned and it is expected to be a major contribution to the upcoming IPCC Assessment Report. A thorough description of CMIP6 is available here, and involves a somewhat different approach than was the case for earlier versions of CMIP. In particular, the planning of various components of CMIP6 has been left to the scientific community to ‘self-organize’ to a large extent. CliC has been active in supporting this to ensure that the Cryosphere is well represented. In particular, we have organized workshops to facilitate the preparation of three model intercomparison activities specifically targeting the Cryosphere. These are:
-ESMSnowMIP – a snow model intercomparison that is part of a broader land surface model intercomparison activity jointly organized with GEWEX
-ISMIP6 – an intercomparison of large-scale ice sheet models
-SIMIP – a diagnostic intercomparison aimed at evaluating the performance of the sea-ice component of CMIP6 global models.

These activities are described in more detail below, and each has an active group of international scientists leading the planning and coordination. The end result will undoubtedly contribute significantly to our understanding of the ability of global Earth System Models to simulate components of the cryosphere and their interactions with other components of the climate system. These intercomparisons also provide valuable information and guidance to model developers by revealing model strengths and weaknesses (through direct comparison to observations), and providing insight into the causes. Furthermore, by assuring that a comprehensive suite of relevant model output is archived, the broader scientific community will be able to probe model results, confront the model results with new observations and process understanding, and provide quantitative projections of future cryosphere changes that support impact assessment and adaptation planning.

One other CliC targeted activity that is not formally a part of CMIP6, but which will be closely aligned, is the Glacier Model Intercomparison Project. This effort will be closely aligned with ISMIP6 and evaluate models of global glacier mass balance which typically make use of climate projections from global Earth System models. GlacierMIP will complement the other CMIP6 cryosphere activities and will certainly provide information relevant to sea-level rise and water availability projections.