Global climate model (GCM)
A General Circulation Model (GCM), more commonly called a global climate model, is a mathematical model of the general circulation of the planet's atmosphere or oceans based on mathematic equations that represent physical processes. These equations are the basis for complex computer programs commonly used for simulating the atmosphere or oceans of the Earth. GCMs are widely applied for weather forecasting, understanding the climate, and projecting climate change. HadCM3 is the GCM used for the UKCP09 scenarios.
HadCM3 is a fully coupled ocean-atmosphere GCM (AOGCM) that was used in UKCP09 for simulating 17 transient projections of climate change. This means that both the atmospheric and the oceanic processes were included in the modelling, hence providing a realistic representation of the climatological processes.
- More details about the climate models used in UKCP09 are given in Box 2.1 in the UKCP09 Climate change projections report. A commentary about the strengths and weaknesses of climate models is given in Annex 3.
Find out more
- IPCC Fourth Assessment Report, Working Group 1 report The Physical Science Basis , Chapter 8.6