Explaining Climate Facts - 1/3 - Climate Balance

1 - Climate Balance
(subtitles available in English and French)
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How warm or cold our planet is depends mainly on the balance between the energy that it gets from the sun, and the energy that it loses to space.
The greenhouse effect is a very important part of this energy balance.
Some of the gases that form our atmosphere reflect the energy that the planet would lose to space back to the surface, exactly like the windows of a greenhouse.
Carbon dioxide, or CO2, is the Greenhouse gas that has the largest effect in changing the energy balance. Large amounts of carbon were stored in fossil form in oil, gas and coal deposits. This carbon is being released into the atmosphere since the beginning of the industrial revolution and the widespread use of fossil fuels. As a result the amount of CO2 in the atmosphere has gone up by 40%, and its increase is accelerating.
Without the Greenhouse effect, our planet would have an average temperature of -18ºC, but with it, we enjoy a relatively comfortable 15ºC average temperature. This energy balance can be influenced by a number of factors.
If a factor lowers the amount of energy that comes in, like dust clouds from a volcanic eruption blocking solar radiation, then the planet gets cooler.
If a factor lowers the amount of energy that goes back into space, then the planet gets warmer.
This can be an increase of the greenhouse effect due to an increase of CO2 in the atmosphere, for example.
A change in the reflectivity, or albedo, of the planet can also have an effect. If the surface gets darker, like when sea ice melts, then more energy is added to the climate system, and if the surface gets lighter, like when areas of dark forests are turned into lighter areas of fields, then more energy is reflected.
Natural phenomena, like the cyclical variations in solar output or the eruption of volcanoes, do have an impact on the energy balance of the climate system, but it is the emission of greenhouse gases by human activity that has the largest effect on the current energy balance.
And so it is the scientific consensus that the current situation is one of shifting balance. The increase of the greenhouse effect results in an excess of energy in the climate system, and the planet is getting warmer.
For more information on climate change, see our in-depth digests on the GreenFacts website:
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