Climatology data used in Climate Change 2007, the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC) calculated from Coupled Model Intercomparison Project Phase 3 (CMIP3) model output.

Simulations of global climate models were run by various climate modelling groups coordinated by the World Climate Research Programme (WCRP) on behalf of the IPCC.

Climatology data was calculated from global climate model simulations of experiments representative of Special Report on Emission Scenarios (SRES) scenarios: A1b, A2, B1, the commitment scenario experiment (COMMIT), the twentieth century experiment (20C3M), the pre-industrial control (PICTL) and the idealised experiments 1PCTO2X and 1PCTO4X.

The AR4 climatologies are 20-year period averages. 30-year period averages have also been calculated for comparison with the IPCC Third Assessment Report (TAR). The monthly climatology data covers the period from 1850-2100. The climatologies are of global scope and are provided on latitude-longitude grids.

The period averages are:
20x: 20-year averages [+20-39, +46-65, +80-99, +180-199] as used in chapter 10 of IPCC 2007,
30a: 30-year averages [+01-30, +31-60, +61-90] as used in the observed climatologies,
30b: 30-year averages [+10-39, +40-69, +70-99] for compatibility with the IPCC 3rd Assessment Report (TAR).

The climatology period averages listed above are relative to AD2000 for SRES scenarios A1B, A2, B1, and the commitment scenario COMMIT, relative to AD1900 for the twentieth century run (20C3M) and relative to the start of the experiment for the pre-industrial control (PICTL) and the 1PCTO2X and 1PCTO4X runs.

Data files are 'tar' files with names of the form [model]_[experiment]_[variable]_{climatology}.tar.

The experiments in this dataset include the SRES future scenarios:
A1B Globalisation with rapid economic growth,
A2 Regionalisation with regionally oriented economic development,
B1 Globalisation with global environmental sustainability.
Also:
COMMIT simulation of climate change we are committed to given the current loading of greenhouse gasses and zero future emissions.
PICTL the pre-industrial control.
20C3M the 20th century climate simulaiton.
1PTO2X and 1PTO4X idealised simulaitons where the concentration of atmospheric carbon dioxide (CO2) is increased by 1 percent per year from pre-industrial concentration until reaching 2x and 4x the original concentration.

The dataset is comprised of monthly mean surface data for the following atmospheric variables:
specific humidity,
precipitation flux,
air pressure at sea level,
surface downwelling shortwave flux in air,
air temperature,
air temperature daily max,
air temperature daily min,
eastward wind,
northward wind.