Climate modelling

Climate models are mathematical descriptions of the climate system which enable us to project how the climate may change in the future. Developments in climate modelling, alongside increasing computing power, mean that scientists have greater confidence than ever before in the ability of climate models to provide useful information about future climate.

Businesses and organisations can use this information to help them to make decisions that have long-term consequences, for example, the construction of a new bridge, planning new schools, future business planning.

However, climate models can’t reproduce the full complexities of the real climate system, and scientists know that there are considerable uncertainties associated with information based on climate models, such as UKCP09.

Producing climate models is a very complex procedure and is carried out in only a handful of countries in the world. The HadGCM is run at the UK Met Office Hadley Centre in Exeter.

To create a global climate model (GCM) the modellers first break the globe down into grid blocks, typically acting at a very coarse resolution of about 3–4 degrees across the globe. The models are then run for the entire globe and values for each grid block, or cell, are returned. Different models are used for different purposes. Models can be an atmospheric-only model, an ocean-only model or a complex atmosphere-ocean coupled model.

In recent years, modellers have developed ways of downscaling these global climate models to provide useful climate change projections for smaller land or sea areas.