CMIP Overview

CMIP is a project of the World Climate Research Programme (WCRP). Members of the CMIP Core Panel are currently working on developing the design of CMIP phase 7 (CMIP7). Task teams have been created to bring in expertise from across the climate science community, each tackling a different aspect of the design. Click here for updates on CMIP7 and for the pages on the CMIP7 task teams. The data output for CMIP phase 6 (CMIP6) is available on the Earth System Grid Federation (ESGF). For more information on CMIP6, click here.

What is CMIP?

The Coupled Model Intercomparison Project (CMIP) is an international climate modelling project, designed to better understand past, present and future changes in the climate. A climate model is a complex computer code that creates a digital analogue to Earth. This model digitises the processes and interactions between parts of Earth’s climate system: the atmosphere, ocean, land surface, cryosphere and biosphere. We use models to experiment how future changes in human activities will impact the Earth’s future climate, how much it warms, how floods, droughts and other extremes will change. However, many processes in our climate occur on such small scales, that models are not able to exactly represent them in models, and therefore some simplifications are required. How we simplify the climate system is unique to each model. Therefore comparing simulations from different models is useful for understanding which results are consistent across models, and which results are less agreed upon. Since 1995, CMIP has been coordinating this model intercomparison across the climate science community. This multi-model approach helps to evaluate climate models, leads to improvements in the model simulations and provides a better understanding of past, present and future climates. One additional strength of CMIP lies in its global infrastructure which has gathered the data and gives open access for a growing global research community. CMIP has grown from a modest scientific research initiative in the early nineties to become a global enterprise: more than 50 modelling centres around the world are participating in the sixth phase of CMIP, CMIP6. Many hundreds of scientific papers have already been published and the results are taken into account for policy decisions. CMIP has been organised in different phases, each with new and improved climate model experiment protocols, standards, and data distribution mechanisms. CMIP6 is the most recent phase to release its modelling output data for general use, whilst the latest phase, CMIP7 is in its earliest organisational stages. CMIP is a project of the World Climate Researcher Programme (WCRP), providing climate projections to understand past, present, and future climate changes. It is part of the WCRP Earth System Modelling and Observations (ESMO) Core Project, which was formed to coordinate all modelling, data, and observation activities across WCRP and its key partners. Under the guidance and at the direction of the Working Group on Coupled Modelling (WGCM), CMIP activities are overseen by a coordinated pair of subcommittees: the CMIP Panel and the WGCM Infrastructure Panel (WIP).This continued collaboration of climate scientists has resulted in CMIP knowledge being extended across the world. As such, this website brings this together to provide a one-stop shop for key resources, events, news, and information for the CMIP community. If there is any information you cannot find on these webpages, please see our FAQs and community-led Q&A forum.

History

In 1995, the WGCM established the Coupled Model Intercomparison Project (CMIP) to provide climate scientists with a database of coupled global model simulations following a standard experiment protocol. The model simulations were used to understand why different models gave different results even when given identical model input and to understand which results are commonly agreed upon between models. In its first two phases, CMIP involved running 18 GCMs in two different configurations:  a “control run” under constant pre-industrial conditions, and a “perturbed run” where atmospheric carbon dioxide was increased by 1% per year over 80 years. The need for state-of-the-art climate science understanding has grown continually over the past twenty years, and as such as have the goals and remit of CMIP.  In 2005-2006, CMIP3 significantly expanded the data outputs of the project with now 25 models participating, and 12 different experiments proposed. This upward trajectory has continued with CMIP5 and CMIP6, each involving more models and more experiments than its predecessor. More information on each of CMIP3, CMIP5, and CMIP6 can be found by following the respective links. Now attention is turning to the planning of CMIP7. A number of task teams have been set up to oversee the design of different aspects of CMIP7. See the task teams and their latest progress updates here.

CMIP Data

From the inception of CMIP, there has been a focused effort to make the model intercomparison data available to scientists besides those who run the models. CMIP has grown over the past two decades, as has the volume of data and number of people wishing to use it. The WIP promotes coordinated development of infrastructure needed to support CMIP, most notably the archiving and serving of CMIP data. CMIP6 data is already in excess of 14 PB of unique data. This data needs to be made available to the international climate science community and increasingly downstream users. The Earth System Grid Federation (ESGF) is a partnership of climate modelling centres dedicated to supporting climate research by providing secure, web-based, distributed access to climate model data.  The ESGF provides secure web access to the CMIP Phase 5 and 6 (CMIP5 and CMIP6) model data enabling search and download of climate data from around the world. For more information on accessing and using CMIP data, see our CMIP Data pages.