A level Biology B · Edexcel 9BI0 · Topic 10E
Climate change
Key points
- The greenhouse effect: gases such as CO and methane absorb infrared radiation emitted by the Earth and keep it warm. Extra gases from burning fossil fuels, deforestation and farming cause global warming.
- Evidence: direct temperature and CO records (e.g. Mauna Loa), ice cores (air bubbles), pollen in peat bogs and tree rings (dendrochronology).
- Effects: changes in species distribution, timing of seasonal events, crop yields, sea levels and the spread of insect vectors.
- Higher temperature changes enzyme activity, so rates of growth and development can rise or fall.
- Models predict future change, but have uncertainties; extrapolating data beyond the range measured is risky.
- Ways to reduce CO: renewable energy, reforestation, and biofuels (carbon released was recently absorbed, though they compete with food crops).
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The Earth's climate is warming, mainly because human activity has increased greenhouse gases in the atmosphere. Biologists need to understand the evidence, predict the effects on organisms, and judge ways to use resources sustainably.
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