Climate model
A mathematical representation of the climate system used to investigate its behaviour and possible responses.
Example
Researchers compare simulations with observations and run different emissions scenarios.
The catch
A projection depends on its assumptions; it is not a prediction of human decisions.
Related terms
Albedo, Atmospheric lifetime, Carbon budget, Carbon dioxide, Climate change, Climate feedback
In more depth
Climate model, explained.
A climate model divides the atmosphere, ocean and land into a grid of boxes stacked in layers and steps the laws of physics forward in time, box by box. Processes smaller than a box, such as individual clouds, have to be approximated, which is a major source of differences between models and one reason estimates of climate sensitivity vary.
Models reproduce the broad pattern of observed warming when driven with historical emissions, and the IPCC weighs observations to temper projections from models that run hot. They are strongest on global averages and long-term trends and weaker on local rainfall, so a regional figure deserves more caution than a global one. Treat a single run as one possible path within natural climate variability, and look for results averaged across many models.