Too much carbon dioxide
What extra CO₂ does to the Earth.
More CO₂ in the air
People burn fossil fuels and cut down forests. Both put more CO₂ into the air.
Is some CO₂ in the air useful to the Earth, or is it all harmful?
What this lesson covers
The idea
Burning fossil fuels and deforestation raise atmospheric CO2; while some CO2 keeps the Earth warm enough for life, excess CO2 intensifies the greenhouse effect, leading to global warming.
More CO₂ in the air
People burn fossil fuels and cut down forests. Both put more CO₂ into the air.
Is some CO₂ in the air useful to the Earth, or is it all harmful?
- Some is needed, too much is harmful
- None is needed
- More is always better
From smoke to warming
Press Next step.
A balance
CO₂ is not a villain in small amounts, since it keeps the Earth warm enough for life. The trouble is the extra CO₂ from burning fossil fuels and cutting down forests. Since 1960 the CO₂ in the atmosphere has risen from 315 ppm to 420 ppm.
Burning fossil fuels and deforestation raise atmospheric CO₂. Some CO₂ keeps the Earth warm enough for life, but excess CO₂ intensifies the greenhouse effect, leading to global warming.
Notes
Burning fossil fuels and deforestation raise CO₂. Some CO₂ keeps the Earth warm enough for life, but excess CO₂ intensifies the greenhouse effect and causes global warming.
Check yourself
Which human activities raise the CO₂ in the atmosphere?
Why is some CO₂ in the atmosphere necessary?
What does excess CO₂ do?
Atmospheric CO₂ rose from 315 ppm to 420 ppm since 1960 (ppm means parts per million). By how many ppm did it rise?
Answer: 105 ppm
- Planting trees. Trees take in CO₂ for photosynthesis, so planting them does not raise the CO₂ in the atmosphere.
- Burning fossil fuels and deforestation — correct. Yes!
- Switching to solar and wind energy. Renewable energy sources help minimise the carbon released into the atmosphere.
- It blocks harmful UV rays. Blocking harmful UV is the job of the ozone layer.
- It makes the troposphere calm. The calm of the stratosphere comes from temperature rising with height, not from CO₂.
- It helps keep the Earth warm enough to sustain life — correct. Yes!
- Intensifies the greenhouse effect and leads to global warming — correct. Yes!
- Weakens the greenhouse effect. Excess CO₂ intensifies the greenhouse effect.
- Cools the Earth. Excess CO₂ leads to global warming, not cooling.