Vicious circles

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Temps de lecture : 2 minutes  

feedback positif rétroaction positive climat

Vicious circles have a specific scientific name : “positive feedback”. This means that once a phenomenon has begun, it will increase or speed up its own development. In the global warming process, at least three types of this effect have been identified.

The first is the melting ice in the Arctic. Indeed, ice is the surface that reflects the sun’s rays the most. Conversely, liquid water is the surface that absorbs them the most. When the ice floe melts, an area that used to send the sun’s heat back into space starts storing it. The more it melts, the more it warms up and so, the more the rest of the remaining surface of the ice floe will melt. This partly explains why the warming observed at high latitudes is about twice as intense as the average.

Another such effect has to do with permafrost, the Far North’s frozen soil. It releases methane – a GEG 25 times stronger than CO2 – as it melts. This speeds up the greenhouse effect and therefore, global warming. This effect could speed up further if methane trapped by the ice at the bottom of oceans is also released. This phenomenon could take on disastrous proportions as there are huge quantities of gas involved.

A third example has to do with the behavior of forests and oceans. Normally, they store huge amounts of CO2 every year but global warming has disrupted their functioning. They might absorb fewer greenhouse gases and could even release some.

The precise mechanisms of these three amplification effects are still subject to debate. Others, like the part global warming plays in fires or cloud formation, still need to be clarified. One thing is certain: beyond a certain point, the situation spirals out of control. This is why researchers are aiming to limit temperature increase to 2°C compared to last century’s average temperatures.


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