What are global climate projections?

Global climate projections are climate model simulations which have been generated by multiple independent climate research centres in an effort coordinated by the World Climate Research Program (WCRP) and assessed by the Intergovernmental Panel on Climate Change (IPCC). These climate projections underpin the conclusion of the IPCC 5th Assessment Report that “Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems”. 

The Climate Model Intercomparison Project (CMIP)

The Climate Model Intercomparison Project (CMIP) was established in 1995 by the World Climate Research Program (WCRP) to provide climate scientists with a database of coupled Global Circulation Model (GCM) simulations.

The CMIP process involves institutions (such as national meteorological centres or research institutes) from around the world running their climate models with an agreed set of input parameters. The modelling centres produce a set of standardised output, when combined these produce a multi-model dataset that can be shared internationally between modelling centres and the results compared. 

Analysis of the CMIP data allows for improving understanding of

  • the climate, including its variability and change, 
  • the societal and environmental implications of climate change in terms of impacts, adaptation and vulnerability,
  • informing the Intergovernmental Panel on Climate Change (IPCC) reports. 


Comparison of different climate models allows for 

  • determining why similarly forced models to produce a range of responses,
  • evaluating how realistic the different models are in simulating the recent past,
  • examining climate predictability.

CMIP5

The fifth phase of Coupled Model Intercomparison Project (CMIP5, 2008-2012) involved 24 modelling centres running their climate models under the prescribed conditions to produce the multi-model dataset designed to advance our knowledge of climate (Taylor et al. 2012). The scientific analyses from CMIP5 were used extensively in the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (IPCC AR5), published in September 2013. 

The CMIP5 data archive is distributed through the Earth System Grid Federation (ESGF) though many national centres have either a full or partial copy of the data for their scientists to utilise. A quality-controlled subset of CMIP5 data are made available through the Climate Data Store (CDS) for the users of the Copernicus Climate Change Service (C3S).

To obtain full details of the whole CMIP5 data archive please refer to the full documentation at the Program for Climate Model Diagnosis & Intercomparison (PCMDI). An introductory factsheet for an overview of an IPCC subset also provides a useful guide to the CMIP5 data. 

CMIP6

The sixth phase of the Coupled Model Intercomparison Project (CMIP6) is in progress. Approximately 40 modelling centres are participating in this phase of CMIP. During the period 2019-2020 modelling centres are standardising and releasing their data to be distributed internationally through the Earth System Grid Federation (ESGF). It is expected that the Climate Data Store (CDS) will begin making CMIP6 data available from 2021.