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Predicting the Future with Climate Models

A model is a representation of something that allows people to see what the actual thing is like and how it works. A model can be especially helpful when it is impractical to take a look at the real version. Global climate models describe the workings of the Earth system to the best of our ability. They are used to predict how the Earth system would react decades into the future if we add greenhouse gasses and aerosols to the atmosphere, deforest land, or otherwise change our world.

To represent the Earth’s atmosphere, global climate models use a three-dimensional grid system that coats the globe and extends upward, dividing the atmosphere into several layers that each includes thousands of points where the model calculates atmospheric processes as it runs. General circulation models (GCMs) are highly complex and have a grid of points with a very fine mesh. They might take into account 10 different levels in the atmosphere, each represented by a grid layer with 65,000 data points, making a total of more than half a million points.

Global climate models use mathematical equations to describe happenings within the Earth system, such as atmospheric processes, the amount of solar energy that enters and Earth's rotation. Complex climate models receive information about Earth processes and anthropogenic change from the calculations of hundreds of different mathematical equations and assesses what sorts of climatic events would result at locations within the grid.

The mathematical equations for a large climate model require quick supercomputers that perform many calculations rapidly, often more than 80 million calculations an hour. The most sophisticated climate models take into account five important components:

  • The biosphere: the amounts of animals and plants
  • The hydrosphere: the oceans and other bodies of water
  • The cryosphere: including sea ice, glaciers and ice sheets
  • The atmosphere: composition and behavior
  • The geosphere: tectonic variations such as volcanic eruptions and moving continents

The climate system is so complex that all models must make some assumptions. However, as scientists continue to study and better understand the processes that go on within the Earth system, our models become more and more accurate.

Delve Deeper...

Visit NCAR’s Climate Modeling Section

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