Greenhouse Effect
Gases trap infrared radiation, keeping Earth warm.
About this topic
Earth is kept about 33 °C warmer than it would be otherwise by greenhouse gases such as water vapour, CO₂ and methane. They let incoming visible sunlight through, but absorb and re-emit infrared radiation from the warm surface, trapping heat.
Burning fossil fuels and deforestation have raised CO₂ from about 280 parts per million before the industrial era to over 420 today, strengthening the effect and warming the planet by roughly 1.2 °C so far. Rising temperatures melt ice, raise sea levels and shift weather patterns. Venus shows the extreme case: a thick CO₂ atmosphere keeps its surface near 460 °C.
Worked example: Earth absorbs about 240 W/m² of sunlight on average and must radiate the same amount back. Without greenhouse gases the surface would sit near minus 18 °C, but with them the average is about 15 °C. A car parked in the sun heats up in a similar way, as glass lets light in but traps heat.
The natural effect is essential for life; the concern is the enhancement caused by human activity. Solutions include renewable energy, energy efficiency and protecting forests. A misconception is that the greenhouse effect and the ozone hole are the same; the ozone hole concerns ultraviolet radiation and is a separate problem.
Key ideas
- CO₂, methane and water vapor absorb IR
- Natural effect makes life possible
- Extra gases warm the planet
Quick check
Use cases: where Greenhouse Effect helps
- Homework: review the key idea behind Greenhouse Effect before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Greenhouse Effect without notes.
- Visual learning: play with the interactive lab to see how Greenhouse Effect changes when you adjust its inputs.
- Teaching a friend: explain Greenhouse Effect in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Greenhouse Effect?
Gases trap infrared radiation, keeping Earth warm.
What will I learn in Greenhouse Effect?
CO₂, methane and water vapor absorb IR. Natural effect makes life possible. Extra gases warm the planet.
Is Greenhouse Effect part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Greenhouse Effect lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Greenhouse Effect?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.