Climate Change: Causes and Evidence
- Earth & Space
- Ages 11–14 · Grades 6–8
What you’ll find out
- Greenhouse gases trap outgoing heat; the natural greenhouse effect keeps Earth habitable.
- Burning fossil fuels and clearing forests have raised carbon dioxide levels, warming the planet.
- Independent evidence confirms warming; societies can mitigate it and adapt to it.
No sign-up and no real names. In the lesson you check your understanding as you read, and practise until it sticks.
The greenhouse effect
Sunlight passes through the atmosphere and warms Earth’s surface, which then gives off heat. Certain gases in the air, called greenhouse gases, such as carbon dioxide and methane, trap some of that heat and keep the planet warm. This natural greenhouse effect makes life possible; without it, Earth would be frozen. However, burning coal, oil and gas, and cutting down forests, have greatly increased the amount of carbon dioxide in the air. More greenhouse gas traps more heat, so Earth is warming.
The evidence and the response
Many independent lines of evidence show that Earth is warming. Temperature records from thousands of weather stations, ships and satellites show a clear rise. Glaciers are shrinking, Arctic sea ice is thinning, and sea levels are rising as water warms and ice melts. Air bubbles trapped in ancient ice reveal that carbon dioxide levels are now far higher than at any time in hundreds of thousands of years. People can reduce warming by switching to renewable energy, using energy efficiently and protecting forests.
Curriculum links: NGSS MS-ESS3-5 · England KS3: Earth and atmosphere · Cambridge Lower Secondary Stages 7–9: Earth and space · NCERT Science, Classes 6–8