“Humanity is walking on a thin layer of ice and this ice is melting quickly,” warned UN Secretary General Antonio Guterres on Monday March 20. And this ice is melting all the faster as global warming accelerates. By the years 2030-2035, it will reach 1.5°C compared to the pre-industrial era, confirmed on Monday March 20 IPCC experts in their new summary reportthe sum of the last nine years of research representing the most up-to-date scientific consensus on climate.
An announcement that appears to be yet another bad news for the planet, whereas since COP21 in 2015 in France, this + 1.5°C threshold was brandished as a compass for climate policies. “Since the Paris Agreements, the stated objective of States has been to keep global warming well below 2°C compared to the pre-industrial era and to step up efforts to limit it to 1.5°C” , recalls Wolfgang Cramer, CNRS research director at the Mediterranean Institute of Marine and Continental Ecology Biodiversity. “It gave a clear horizon and target for climate policies.”
“And indeed, today, looking at the different possible trajectories and the weak efforts put in place by governments, it seems very difficult to achieve this second objective”, continues the specialist, who had been one of the main authors. from a previous IPCC report published in February 2022.
The numbers speak for themselves. Today, according to the summary published on Monday, to have a chance of keeping warming at 1.5°C, we would have to reduce greenhouse gas emissions by around 45% by 2030 compared to today’ today. This would amount to experiencing the same decline each year as that experienced in 2020, in the midst of the Covid-19 pandemic, when economies around the world were at a standstill.
A colossal drop while the planet seems for the moment to take the opposite trajectory. According to the IPCC, it is heading for a warming of 2.5°C by the end of the century if the promises made by the States are respected, 2.8°C by following their current policies.
Global warming, the “fever” of the planet
But for all that, we must not fall into fatalism, agree to say the experts. “Because our current actions will also determine the extent of climate change in the longer term”, explains Wolfgang Cramer. “The objective, always, is to manage to stay as low as possible.”
“This goal, anyway, was already too much… We see it today: we are already at 1.2°C of warming and we are suffering the consequences with the multiplication of heat waves, droughts, floods… “, he continues.
To understand the importance of these additional fractions of degrees, the specialist draws a parallel with a human suffering from fever. Usually, an individual’s body temperature is 37°C. If we add 1°C to it, he will be unwell and will have a slight headache. At 2°C, it will suffer even more. But at 3°C, it can become dangerous, especially if the person is vulnerable.
The same goes for the planet. “The consequences will not be the same at each degree and in different parts of the globe. For the most vulnerable, the consequences will be much greater than for those who are less so,” he explains. “1.5°C will always be better than 1.6°C, which will always be better than 1.7°C. Every tenth of a degree counts.”
First threat to biodiversity
The illustrations of the consequences of this “fever” of the planet are numerous. Among them: the extinction of biodiversity. The Bramble Cay Melomys, a small rodent that lived on small islands between Australia and Papua New Guinea has already disappeared due to global warming. “Scientists have shown that its disappearance is due to the submersion of its habitat”, detailed to France 24 last December Camille Parsesan, director of research at the CNRS and specialist in the links between biodiversity and climate. “We also noted the disappearance of 92 species of amphibians, killed because of the proliferation of a fungus. We have proof that this one developed because climate change, by modifying the ecosystems, caused it to offered favorable conditions.” Another glaring example: corals. At 1.5°C, 70-90% of them might disappear. At 2°C, the figure rises to 99%.
Today, according to IPBES – the UN’s biodiversity experts – more than a million species are threatened with extinction and “climate change is on the way to becoming the most important threat to them”. “The more it increases, the more the ecosystems are disturbed, with consequences for the fauna and flora”, they note in a report published in 2021.
>> To read also: “Biodiversity, both victim and tool in the fight once morest global warming”
“More and more intense weather phenomena”
“Each additional degree will also result in more and more intense weather phenomena,” insists Wolfgang Cramer. “With ever greater impacts for the 3.3 billion people who live in vulnerable areas.”
For some years, some scientists are indeed working on the “science of attribution”, which aims to study the links between extreme weather events and climate change. Through their work, they confirm that heat waves, floods or hurricanes are increasing in intensity, scale and frequency in connection with global warming. They estimate, for example, that it made the heat wave that affected India and Pakistan in March and April 2022 thirty times more probable.
“Faced with these threats, our efforts must also make it possible to slow down the warming as much as possible”, abounds for his part Gerhard Krinner, glaciologist and one of the authors of the summary for policymakers published on Monday. “It’s just as important. The faster the warming goes, the less time people will have to adapt. This will increase the risk of shortages, famines or conflicts.“
Not to mention, notes the glaciologist, that some changes will be irreversible and must therefore occur “as late as possible”. “An extinct species, for example, will not be able to reappear,” he quotes. “A melted glacier will have a lot of trouble recreating itself. The rise in water levels, meanwhile, will continue for centuries more or less quickly depending on the warming.”
The fear of tipping points
Finally, the two specialists warn once morest “tipping points”. “These events, for which it is very difficult to know at what stage of global warming they might occur and which would have major consequences for the planet”, insists Wolfgang Cramer.
“This is the case, for example, destabilization of the Antarctic ice sheet. The probability of this happening today is low but increases with global warming with real risks of a huge acceleration in sea level rise between 1.5°C and 2°C.” Concretely, if the frozen ground (permafrost) of Antarctica were to melt, it would release billions of greenhouse gases stored in its ice, which would then warm the planet and further accelerate the melting of the ice – a vicious cycle. cited: the transformation of the Amazon rainforest into savannah or even the melting of the Greenland cap.
All these scenarios can be avoided, hammer the two specialists. “Today, we have many solutions in hand, which are available and effective, to slow down and limit climate change. The obstacles are no longer in the area of innovation but political”, concludes Wolfgang Cramer. “The efforts we are making now will make all the difference in the long term and can still save us those extra tenths of a degree,” concludes Gerhard Krinner.
