has the point of no return already been passed?

State environmental policies, but also those of the private sector, aim to reduce CO2 emissions, to limit the increase in average temperatures, and to avoid the most serious consequences of such climate change. But according to one article scientist published in the famous journal Nature on November 12, global warming has already passed the point of no return of the 2.3 ° C increase in temperature. Even if emissions of CO2 and other greenhouse gases were immediately and completely stopped, the 2.3 ° C increase would be reached by 2070. After this period, temperatures will drop but then rise again to approximately 4 ° C in 2500.

Methane release from melting permafrost will fuel warming for hundreds of years

This article has identified this point of no return based on the ESCIMO climate model. According to this model we have reached the temperature where permafrost, the frozen ground of the poles, slowly melts. This melting causes a small continuous release of methane that will fuel warming over the next few centuries. This phenomenon is a vicious cycle, caused by the release of methane, but also by reflection from the sun (caused by melting ice and snow) and higher atmospheric humidity (caused by higher temperatures). This cycle seems to start from a global warming of barely 0.5 ° C above the pre-industrial level, in the middle of the 19th century.

The ESCIMO model, complete enough to make predictions?

Dorota Retelska, an expert in climatology, explains in the Swiss newspaper Le Temps, that this model is incomplete, because warming can increase the absorption of CO2 by the biosphere, but can also be impacted by droughts, which cause a significant emission of carbon from the ground.
For Daisy Dunne, in the British daily The independent, this model is also a bit simplistic. Some climatologists therefore ask public opinion to take these results with caution, because this model would not be credible enough to make predictions.

Sea ice is melting at an alarming rate, and this would not have been taken into account

One of the criticisms of the ESCIMO model, used in the new study, is that it does not simulate how global warming works well. The warming of the world’s oceans and atmosphere must also be taken into account. Bright white ice reflects sunlight, and once it disappears, the dark ocean begins to absorb more sunlight, which heats the waters further, and leads to further ice melting.
The results of the study are finally in contradiction with the conclusions of the assessment report of the Intergovernmental Panel on Climate Change (IPCC) which uses models that can also simulate the behavior of the Earth’s feedback loops. .
While the authors of the article are also aware that their model may be too simple, their intention is to encourage other researchers to supplement these predictions.

We must therefore take these conclusions with caution, and above all, we must under no circumstances use this supposed crossing of the point of no return as an argument to stop the efforts against global warming. On the contrary, it is more than ever necessary to coordinate strategies to reduce CO2 emissions as much as possible, and to try, if this has not already been done, never to reach the point of no return which would trigger a vicious circle of disastrous consequences. .

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