BIOLOGY · Stage 8 · Chapter 8: Weather and Climate
Biology 8.2 Climate and climate change — Greenhouse Gases and Global Temps — Alhussan International Academy - Biology (Stages 7-9) Revision Notes & Topical Questions
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Lesson summary
8.2 Climate and climate change — Greenhouse Gases and Global Temps — Alhussan International Academy — Biology (Stages 7–9) notes: Distinguish weather from climate and explain the greenhouse effect and how increased greenhouse gases are changing global temperatures.Climate = the l…
- Shared features
- Difference
- Temperate climates
- Fossil evidence
- Present change
- Incoming radiation
Section 1 of 7Weather and climate
- Climate = the long-term weather pattern of an area, found from average conditions over years, centuries or thousands of years.
- Climate tells you what weather to expect, while weather is what you actually get.
- Shared features
- both involve rainfall, wind, sunshine, humidity and temperature.
- Difference
- everyone shares weather today, but different parts of the world have different climates.
Section 2 of 7Climatic zones
| Zone | Main pattern | Example |
|---|---|---|
| Tropical | Hot and humid with lots of rainfall; strong winds and hurricanes | Caribbean countries |
| Arid | Very dry with very little rain | Desert countries |
| Mediterranean | Hot dry summers and cool wet winters | Italy |
| Temperate | Mild summers and cool winters | UK |
| Continental | Short hot summers and long cold winters | Russia |
| Polar | Extremely long, very cold winters and short cold summers | Greenland |
- Temperate climates
- temperatures change by 30 °C or more between summer and winter, and hurricanes are very rare.
Section 3 of 7Climate has changed before
- Fossil evidence
- parts of the world that are now cool were once tropical oceans.
- Trilobite fossils found in the UK show that its climate 428 million years ago was very different from today.
- Present change
- the temperature at the Earth's surface is now rising in all climatic regions, from the polar ice to the tropics, relatively quickly.
Section 4 of 7The natural greenhouse effect
- Incoming radiation
- the Sun emits short-wave radiation, including visible light, which passes through the atmosphere and warms the Earth's surface.
- Outgoing radiation
- the warm surface emits longer-wave infrared radiation.
- Greenhouse gases
- mainly carbon dioxide, methane and water vapour absorb some infrared radiation and re-emit it in all directions, including back to the surface.
- Result
- the planet is warmer than it would be otherwise.
- Without the natural effect the average temperature would be about −18 °C instead of about 15 °C.
Section 5 of 7The enhanced greenhouse effect
- Cause
- human activities have increased greenhouse gas concentrations, strengthening the effect and causing global warming.
- Carbon dioxide
- it comes from burning fossil fuels in power stations, vehicles and industry, and from deforestation, which removes trees that take in carbon dioxide.
- Methane
- it comes from cattle and sheep, rice paddies and rubbish in landfill sites.
- Nitrous oxide
- it comes from fertilisers and some industrial processes.
- Data
- carbon dioxide has risen from about 280 ppm before the industrial revolution to over 420 ppm today.
- Global average temperature has risen by about 1.1 °C since the late 1800s.
Section 6 of 7Consequences of climate change
| Effect | Explanation |
|---|---|
| Rising sea levels | Ice on land melts and seawater expands as it warms; low coasts flood |
| More extreme weather | More heat energy powers droughts, heatwaves, storms and floods |
| Changes to habitats | Species move or die out; coral reefs bleach |
| Effects on farming | Crop yields change; some regions become too dry |
Section 7 of 7Reducing the problem
- Cutting emissions
- use renewable energy such as wind, solar and hydroelectric power, improve energy efficiency and use public transport.
- Absorbing carbon dioxide
- plant trees and protect forests.
- Cooperation
- international agreements set targets, but progress needs governments, industry and individuals.
- Mitigation and adaptation
- mitigation cuts emissions, while adaptation copes with change, such as building sea walls.
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