Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

5.3.2Unit 5: Respiration, Internal Environment, Coordination and Gene Technology

Anthropogenic Climate Change — IAL Edexcel Linear Revision Notes & Topical Questions

5 min read 6 parts Lesson 26 of 36 Unit quiz

📚 IAL Edexcel Linear Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
Curriculum Equation Key معادلة التنفس الخلوي الهوائي الموزونة - Balanced Cellular Respiration EquationFast Exam Solution
C₆H₁₂O₆ + 6O₂ ➔ 6CO₂ + 6H₂O + 36-38 ATP
Word Equation & Conditions: Glucose + Oxygen -> Carbon Dioxide + Water + Energy (36-38 ATP) | جلوكوز + أكسجين ← ثاني أكسيد كربون + ماء + طاقة
Location & Specifications: الميتوكوندريا (Mitochondria) والسيتوسول.
0%read

Section 1 of 6The Greenhouse Effect

Be precise with termsthe greenhouse effect is the natural process, while global warming is the extra temperature rise caused by raised gas levels.

Incoming energy
  • Incoming energy Sunlight warms the Earth, and the warmed surface then re-radiates energy outwards as infrared radiation.
Greenhouse gases
  • Greenhouse gases Gases such as carbon dioxide and methane absorb some of this infrared radiation and so slow its escape into space.
A natural process
  • A natural process The greenhouse effect is natural and keeps Earth warm enough for life, with far smaller swings in temperature than a planet without it.
Enhanced effect
  • Enhanced effect More greenhouse gas in the air traps more radiation, so the average temperature of the lower atmosphere rises.

Section 2 of 6Where the Extra Carbon Dioxide Comes From

Where the Extra Carbon Dioxide Comes From
Fossil fuels
  • Fossil fuels Burning coal, oil and gas for transport, electricity and industry releases carbon that was locked away for millions of years.
Deforestation
  • Deforestation Clearing forests removes trees that were absorbing carbon dioxide and often releases carbon when the wood is burned or rots.
Soils and peat
  • Soils and peat Draining or harvesting peat bogs and degrading soil exposes stored carbon to decay, which releases it as carbon dioxide.
Warming oceans
  • Warming oceans Warmer water holds less dissolved gas, so a warming ocean can release carbon dioxide rather than absorb it.

Section 3 of 6Methane Sources

1
Methane (CH₄) is a hydrocarbon and the main component of natural gas, and it is also a greenhouse gas.
2
Intensive farming of ruminant animals such as cattle raises methane levels because microbes in their guts release it.
3
Waterlogged rice paddies provide anaerobic conditions where bacteria produce methane that escapes into the air.
4
Landfill sites release methane as buried organic waste is broken down by microorganisms without oxygen.
5
Extracting fossil fuels releases methane, and warming can thaw permafrost and release the methane trapped in frozen ground.

Section 4 of 6Reading the Evidence

Trend
  • Trend Carbon dioxide has risen from about 280 ppm before industrialisation to above 400 ppm today, alongside rising mean temperature.
Correlation
  • Correlation Matching trends show a correlation, but correlation alone does not prove that one variable causes the other.
Stronger case
  • Stronger case The link is supported by the known ability of carbon dioxide to absorb infrared radiation and by many independent data sets.
Other factors
  • Other factors Temperature also fluctuates when carbon dioxide is steady, so other influences such as volcanic activity are involved.

Section 5 of 6Worked Example

Question

  • Carbon dioxide rose from 280 ppm to 420 ppm.
  • Calculate the percentage increase.

  1. Find the change420 − 280 = 140 ppm.
  2. Divide by the original value140 ÷ 280 = 0.5.
  3. Multiply by 100 to give a percentage.

Answer 50% increase.

Section 6 of 6Exam Checklist & Tips

5.3.2 – Key Points for the Exam

  • Greenhouse gas A gas that absorbs infrared radiation re-emitted from the Earth and so traps energy in the atmosphere.
  • Anthropogenic Caused by human activity.
  • Carbon sink A store that takes in more carbon than it releases, such as forests, soils, peat and the oceans.
  • Permafrost Ground that stays frozen throughout the year.
  • ppm Parts per million, a unit for the concentration of a gas in air.

Common Mistakes

  • Using greenhouse effect and global warming as if they mean the same thing, when the first is natural and the second is the enhanced rise.
  • Saying that carbon dioxide levels were constant before humans;
    • they have always varied naturally, but never as quickly.
  • Writing that a correlation proves causation; say only that the data are consistent with it.
  • Forgetting methane, which is a different gas from carbon dioxide and has its own human sources.

Last updated:

\n