Global warming is quite a recent phenomenon that came to international prominence only by the end of the 20th century.
But man-made pollution was known to affect the climate system of the planet as long ago as the middle – end of the 19th century.
It was first suggested in 1863 that changes in the composition of the atmosphere due to pollution could lead to climate change. In 1896 the Swedish scientist Svante Arrhenius made first actual calculations of the effect of greenhouse warming in which he estimated that a doubling of carbon dioxide in the atmosphere would increase the global average temperature by 4 ° C to 6 ° C.
Mechanism of global warming
In order to understand the mechanics of global warming, let’s see how the Earth is “powered” by the Sun (through solar radiation), how the energy (radiation) between these two entities is continuously recycled, and how this cycle maintains the equilibrium temperature of the Earth.
Here is how this process works:
1. The Earth receives its original supply of shortwave radiation from the Sun
2. The Earth then reflects 30% of this solar radiation back into space in its original shortwave form
3. The Earth absorbs the remaining 70% of this solar energy and then re-radiates it back into space in the longwave form (infrared radiation)
4. So in order to maintain thermal equilibrium, the amount of shortwave and longwave radiation leaving the Earth must be equal to the amount of the original shortwave radiation received from the Sun.
Thus, for a certain amount of radiation being exchanged with the Sun the Earth will achieve a certain equilibrium temperature. When there is a change in this equilibrium the problem begins.
The Earth’s atmosphere is a unique environment which consists of a number of naturally occurring gases.
The content of the atmosphere is roughly as follows:
Nitrogen (around 78% of the total)
Oxygen (around 20% of the total)
Water vapor (substantial amount)
Carbon dioxide (small amount)
Trace gases (hydrogen, argon, helium and other gases)
It is exactly some of these gases in the atmosphere (e.g., water vapor and carbon dioxide) that trap the upward-going longwave radiation emitted by the Earth, re-emit it in all directions and thus contribute to the warming of the planet.