If your 10-year-old nephew or your colleague Brigitte asked you: But what is the greenhouse effect exactly?“, could you take up the challenge in a few words? We hear about it every day, we all have a vague idea of what it is, but not sure that everyone has understood that this natural phenomenon is essential to our survival… We’re going to fix that.
Yes, the greenhouse effect is good for the planet.
Yes, the greenhouse effect is essential to life on earth.
Yes, the greenhouse effect has an interest and not only for tomato plants.
So what is the greenhouse effect? ?
We often do a amalgam between the greenhouse effect and global warming, but that’s not quite fair.
It is important to fully understand the definition of the greenhouse effect in order to fully understand climate issues. So my goal today is to give you one simple definition.
When solar radiation reaches the Earth’s atmosphere, some (about 30%) is directly reflected, that is to say sent back to space (by the atmosphere and clouds).
The rays that have not been reflected back to space are absorbed by the atmosphere for 20% of them while 50% finally reach the earth’s surface.
Of these, a part is still reflected by the earth depending on the nature of the surface of the ground (for example, the ice reflects the sun’s rays better than the earth).
Without the greenhouse effect, we would all be frozen!
Rays that are not reflected are absorbed by soil and oceanscausing them to heat up.
Then some of that heat is released back into the air as infrared. These infrared rays remain partially imprisoned in the atmosphere and heat it. It is this heating because of the infrared rays which is called the greenhouse effect.
It’s exactly like in a greenhouse which allows the sun’s rays to pass through, but traps the infrared which heats up the interior of the greenhouse.
It is thanks to the greenhouse effect that we have an average temperature of 15°C on earth.
Without the greenhouse effect, the average temperature would be around -18°C.
You noticed that I just explained the greenhouse effect and I didn’t talk about it at all. global warming. The greenhouse effect is indeed a physical phenomenon which explains why we are all here today and which we need to survive.
If someone asks you: “What is the greenhouse effect? » : I am sure that you will be able to explain it with your words. But if you want to understand the phenomenon on video, the one I put for you above explains the phenomenon very well.
Why are we being beaten up with this?
It’s true that, if it’s a natural phenomenon, why do we come to beat our ears with this subject?
The amount of heat retained in the atmosphere by the greenhouse effect depends on the concentration of certain gases which are contained in the atmosphere. These gases (called greenhouse gas) capture infrared radiation and increase the part of radiation that remains in the atmosphere instead of leaving beyond it.
It therefore increases the atmosphere temperature. The higher the concentration of greenhouse gases, the higher the average temperature of the atmosphere.
Finally, it is not the greenhouse effect that causes the global warming. It is the increase in the concentration of greenhouse gases which, increasing the natural greenhouse effect, causes global warming.
In conclusion, the greenhouse effect is a physical phenomenon, the greenhouse effect has always existed, the greenhouse effect has created the conditions conducive to life.
What we need to understand now is what greenhouse gases are and how human action causes their concentration to vary.
We will see that in a future article.
