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8.2Chapter 8: Weather and Climate

Climate and climate change — Alhussan Biology - Stage 8 Revision Notes & Topical Questions

5 min read 9 parts Lesson 2 of 6 1 quiz

📚 Alhussan Biology - Stage 8 Hub / Topical Revision
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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

Part 1 of 7Weather and climate

Weather and climate
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
  • Shared features both involve rainfall, wind, sunshine, humidity and temperature.
Difference
  • Difference everyone shares weather today, but different parts of the world have different climates.

Part 2 of 7Climatic zones

ZoneMain patternExample
TropicalHot and humid with lots of rainfall; strong winds and hurricanesCaribbean countries
AridVery dry with very little rainDesert countries
MediterraneanHot dry summers and cool wet wintersItaly
TemperateMild summers and cool wintersUK
ContinentalShort hot summers and long cold wintersRussia
PolarExtremely long, very cold winters and short cold summersGreenland
  • Temperate climates
    • temperatures change by 30 °C or more between summer and winter, and hurricanes are very rare.

Part 3 of 7Climate has changed before

Fossil evidence
  • 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
  • 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.

Part 4 of 7The natural greenhouse effect

Incoming radiation
  • Incoming radiation the Sun emits short-wave radiation, including visible light, which passes through the atmosphere and warms the Earth's surface.
Outgoing radiation
  • Outgoing radiation the warm surface emits longer-wave infrared radiation.
Greenhouse gases
  • 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
  • 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.

Part 5 of 7The enhanced greenhouse effect

Cause
  • Cause human activities have increased greenhouse gas concentrations, strengthening the effect and causing global warming.
Carbon dioxide
  • 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
  • Methane it comes from cattle and sheep, rice paddies and rubbish in landfill sites.
Nitrous oxide
  • Nitrous oxide it comes from fertilisers and some industrial processes.
Data
  • 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.

Part 6 of 7Consequences of climate change

EffectExplanation
Rising sea levelsIce on land melts and seawater expands as it warms; low coasts flood
More extreme weatherMore heat energy powers droughts, heatwaves, storms and floods
Changes to habitatsSpecies move or die out; coral reefs bleach
Effects on farmingCrop yields change; some regions become too dry

Part 7 of 7Reducing the problem

1Cutting emissions
  • Cutting emissions use renewable energy such as wind, solar and hydroelectric power, improve energy efficiency and use public transport.
2Absorbing carbon dioxide
  • Absorbing carbon dioxide plant trees and protect forests.
3Cooperation
  • Cooperation international agreements set targets, but progress needs governments, industry and individuals.
4Mitigation and adaptation
  • Mitigation and adaptation mitigation cuts emissions, while adaptation copes with change, such as building sea walls.

Key terms

TermMeaning
ClimateThe long-term weather pattern of a region.
Greenhouse gasA gas that absorbs infrared radiation and warms the atmosphere.
Greenhouse effectThe warming of the Earth by gases that trap heat in the atmosphere.
Global warmingThe rise in average global temperature.
MitigationReducing emissions to slow climate change.
AdaptationCoping with the effects of climate change.

Avoid these mistakes

1
Saying the greenhouse effect is bad — the natural effect is essential; the enhanced effect is the problem.
2
Confusing global warming with the ozone layer hole — they are different problems.
3
Thinking weather proves climate change — climate is measured over decades.
4
Saying carbon dioxide traps visible light — it absorbs infrared radiation.

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