Greenhouse effect — Science definition
Defined in 2 courses:
- The natural process by which greenhouse gases trap some of Earth's outgoing heat, keeping the lower atmosphere warm enough for life. (Earth & Space Science)
- The trapping of outgoing heat by atmospheric gases that absorb and re-radiate infrared energy, keeping Earth's surface warmer than it would otherwise be. (Physics & Environmental Science)
Where it is taught
- Climate & the Greenhouse Effect — Oceans, Carbon & Climate, Earth & Space Science, Grade 9
- Climate Change — Pollution, Carbon & Climate Evidence, Physics & Environmental Science, Grade 12
In use
Underneath every one of Earth's climates sits the greenhouse effect — and despite its bad reputation, in its natural form it is the reason we're alive.
Climate & the Greenhouse Effect
The natural greenhouse effect keeps Earth’s surface substantially warmer than a simplified no-greenhouse radiative model.
Climate Change
Questions using greenhouse effect
Problem 1
- The greenhouse effect itself is natural and necessary; the concern is that human activity is increasing greenhouse gas concentrations, enhancing the effect and raising temperatures further.
- There is no difference; they are the same process.
- The greenhouse effect only happens at the poles.
- Global warming is caused by too much oxygen in the atmosphere.
Answer and explanation
The greenhouse effect itself is natural and necessary; the concern is that human activity is increasing greenhouse gas concentrations, enhancing the effect and raising temperatures further.
The natural greenhouse effect keeps Earth livable. The concern is that burning fossil fuels and other activities have added extra greenhouse gases, intensifying the natural effect and pushing global average temperatures higher.
Problem 2
Answer and explanation
The greenhouse effect itself is natural and necessary — without it, Earth would be far too cold to support life as we know it. The real problem is that human activities have increased the amount of greenhouse gases in the atmosphere, enhancing the natural effect beyond its normal balance and causing global temperatures to rise; the goal is to reduce that extra human-caused increase, not eliminate the greenhouse effect altogether.
Problem 3
- block incoming sunlight
- absorb and re-emit outgoing infrared radiation
- cool the surface
- destroy ozone
Answer and explanation
absorb and re-emit outgoing infrared radiation
They are largely transparent to incoming sunlight but absorb the infrared Earth radiates back.
Problem 4
- much warmer
- about the same
- much colder
- unchanged in temperature but darker
Answer and explanation
much colder
The natural greenhouse effect keeps the surface well above what sunlight alone would produce.