Guide: How to understand and interpret global climate model results

Global climate models (GCMs) are the most widely used method to understand future climate change. A new guide from the Future Climate for Africa Programme explains how to interpret GCM results, in order to understand what models tell us about likely future climate. This guide complements a previous FCFA publication on how climate models can be used in planning.

A wide variety of climate model results are available due to uncertainty related to how the climate will change in the future, the many sets of climate model projections available, as well as the many ways of visualising projections. GCM results can be presented visually in formats such as graphs, maps and increasingly innovative presentations like infographics and animations. Each approach has positives and drawbacks. This guide takes readers through the different presentations to better understand and interpret model results. Key messages include:

  • Climate model results are not predictions or forecasts. Because of the uncertainties of GCM results, they are referred to as ‘projections’ (plausible descriptions of future climate). Climate model projections are also not final. Models are constantly being refined as new understandings of the climate system emerge.
  • Model results are most commonly presented as a time series graph or a map. Time series graphs are useful for showing changes in climate extremes and variability, and how the rate of change varies over time. Time series can also provide information about changes in monthly climate patterns, which is useful for informing planning decisions. Maps present data spatially and make it easy to see what is projected in different locations. However, they are limited by the coarse resolution of GCMs (each grid cell is roughly 200km x 200km).
  • New and innovative ways of visualising and presenting climate information now exist, such as infographics and animations, which typically provide greater context and more information about climate impacts. However, these alternative approaches must accurately reflect levels of uncertainty and avoid alarming messages. A good example of an innovative presentation of global temperature change is Ed Hawkins’ animated climate spiral.

UMFULA research team members Declan Conway, Katharine Vincent, Sam Grainger, Emma Archer van Garderen and Joanna Pardoe wrote the guide.