We emit CO2. The forests are burning. The ice cream is melting. The Earth is heating up. Inexorably. And more and more headlines are warning us. The point of no return is near. Although some researchers note that the concept may have little meaning in ecology. Each deterioration brings its share of consequences.
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A point of no return is a threshold not to be exceeded. Otherwise theecosystem could suddenly deteriorate. Or even purely and simply disappear. To get an idea, the image of a cup that is pushed to the edge of a table is interesting. Because the moment comes when a little extra push causes the cup to fall. No hope of turning back.
Scientists have thus defined a whole series of potential points of no return. What lead them initially to think that our survival on Earth would not be irreversibly endangered before a temperature rise around 5°C compared to pre-industrial temperatures.
But at the end of the 2010s, they revised their estimates, judging that a temperature increase of 1 to 2°C could be enough to trigger a cascade of disaster. However, between 2016 and 2020, the global temperature of the Earth had already increased by 1.1°C compared to these famous pre-industrial averages. The 1.5°C mark should be crossed by 2030.
Our carbon clock is ticking
The Intergovernmental Group of Experts on the Evolution of the weather (IPCC) warned in 2018 that with a rise in temperatures of 1.5 to 2°C, the world would no longer be the same. That we would have to face increased risks for species — including ours — and savings. that the stability and resilience of our planet would be called into question. It is on this basis that the Mercator Research Institute on Global Commons and Climate Change (MCC) imagined a carbon clock. A clock that counts down the time we have until we have emitted enough carbon to reach this point of no return.
If we want to stay below the +1.5°C mark, we will not be able to emit – since the end of 2017 – more than 420 gigatonnes of CO2. Which brings us, to the emission level of greenhouse gas today, just over nine years from now — the end of 2027. To break the +2°C mark, it will take about 26 years — so it will happen by about the end of 2045.
The Arctic on the brink of rupture
From a less global point of view, on the side ofArctic, the situation seems ready to change. Since the early 2000s, theice sheet Greenland is inexorably losing its ice. Mainly as a result of rising temperatures in theair. And this ice is no longer regenerated by snowfall. Prior to 2050, the region is expected to experience ice-free summers.
Scientists have placed the point of no return slider somewhere between +1.5°C and +3°C. I’collapse of the ice cap might take centuries, it would become what the researchers describe as irreversible. The only way to go back would then be to cool our planet well below these temperatures.
The Amazon in danger
In the Amazon, the deforestation progresses a little more each year. According to Carlos Nobre, climatologist at the University of Sao Paolo, the point of no return — the moment when the Amazon rainforest, one of the largest forests in the world, will have become unable to sustain itself — is somewhere around 20-25% deforestation. We are now at 17%! It is difficult to predict when the border will be crossed. What is certain is that we are getting dangerously close.
planet on fire
More than 18 million hectares went up in smoke in Australia during the season from Forest fires 2019-2020. Mega-fires in the western United States and Arctic. Scientists had predicted an increase in forest fire activity as a result of the global warming. But they didn’t expect it to happen so quickly.
According to them, rising global temperatures and worsening droughts ushered the world into a new era. And the methods of fighting these fires will have to be reviewed. Clearing of meadows, drone monitoring systems or even computer models simulating the departures of fire could be part of the solution.
What if there was no point of no return?
At the same time, some ecologists are asking the question. Does this idea of a point of no return correspond to an ecological reality?
In August 2020, they sifted through some 4,600 studies of ecosystems in which degradation was observed due to climate change. Result: a point of no return could be observed in only 5% of cases. From a certain increase in temperature and a disappearance of Pisces herbivores, the Coral reefsfor example, are giving way to prairies ofalgae. But for most ecosystems, the deterioration of the environment appears progressive. With consequences from the first disturbance.
Act urgently
If one thing is certain, it is that the uncertainties in matter changes in the climate and ecosystems remain numerous. Some researchers believe, for example, that the melting ice could lead to an increase in clouds and indeed, snowfall. What ultimately slows down the process in a feedback loop. Just as a slowdown in the Atlantic Meridional Overturning Circulation (AMOC) could help slow the rate of ice melt.
But all scientists agree on one point: at the end of 2020, nothing is yet lost. Subject to drastically reducing our emissions of greenhouse gas from today.
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