Modelling Climate Change
- Earth & Space
- Ages 14–18 · Grades 9–12
What you’ll find out
- Climate models divide the Earth system into grid cells and apply the laws of physics, stepping forward in time.
- Models are tested by hindcasting, and past projections have proved broadly accurate.
- Future warming depends mostly on emissions: about 1.8 °C by 2100 with deep cuts, about 4.4 °C with very high emissions.
No sign-up and no real names. In the lesson you check your understanding as you read, and practise until it sticks.
How climate models work
Climate models are computer programs that represent Earth’s climate system mathematically. They divide the atmosphere, oceans, land and ice into a three-dimensional grid of cells, often about 100 kilometres across. In each cell, the model uses the laws of physics to calculate temperature, wind, humidity and other quantities. It then works out how energy, air and water flow between neighbouring cells, step by step through time. Only supercomputers can run these huge calculations. Processes smaller than a cell, such as individual clouds, must be estimated. Scientists test models through hindcasting: running them over the past and comparing the results with real observations. Models from the 1970s correctly projected the warming that followed.
Scenarios and forecasts
Future warming depends largely on how much greenhouse gas humans emit, which no model can predict. So scientists run models under a range of emissions scenarios. Earth has already warmed by about 1.2 degrees Celsius since the late 1800s. In a scenario with rapid, deep cuts in emissions, models project warming of around 1.8 degrees by 2100. With very high emissions, they project around 4.4 degrees. Models agree on many regional effects. Heatwaves and heavy downpours become more frequent and intense. The Arctic warms fastest, and sea level keeps rising for centuries. Uncertainty remains, especially about clouds, but human choices matter most. Even with deep cuts, some further warming is now unavoidable for decades.
Curriculum links: NGSS HS-ESS3-5 · NGSS HS-ESS3-6 · England KS4: Chemistry · Cambridge IGCSE: Environmental Management · NCERT Geography, Class 11