What are climate models?

Climate models are used to calculate the future climate and produce climate scenarios. These models are three-dimensional representations of the atmosphere, land area, ocean, lakes and ice. 

In global climate models the atmosphere is divided into a grid horizontally along the earth’s surface and vertically into the air. At every point in the grid the development of different meteorological, hydrological and climatological parameters in time are calculated. For global models the size of each square in the grid is 100—300 km, while in regional models a smaller area of the earth is modeled e.g. over Europe with grid squares of 25—50 km. Over a smaller area, a denser grid can be created without demanding so much extra computer power so greater detail can be achieved. What happens outside the calculated area in a regional climate model is controlled by the results of the global climate model so that consideration is also taken to changes outside of the regional model area. 

At the local level, one would on the first hand choose regionally downscaled climate information if it is available, as the detail in regional models is greater. If this is not available, even information from global climate models can give some indication of future climate, but in a coarser way.