According to the study, there were five climate perturbations, the sudden melting of boreal permafrost, the collapse of the Greenland and West Antarctic ice sheets, the rapid disappearance of coral reefs and the termination of the organization of ocean currents in the Labrador Sea. .
Based on numerous academic and scientific works, the study reveals that these tipping points will lead to an irreversible collapse of the climate system.
Even more alarming: the study reveals that four reference points go from Possible
at Possible
1.5°C global warming. These include the sudden melting of boreal permafrost, the collapse of the Greenland and West Antarctic ice sheets, and the rapid disappearance of coral reefs.
What we are seeing are various negative impacts such as sea level rise and coral reef death
said the paper’s co-author David Armstrong McKay, an expert on climate issues and a visiting scholar at the University of Exeter in England.
The findings also raise questions about whether the international Paris Agreement’s goal of limiting global warming to well below 2°C and well below 1.5°C is enough to avoid climate catastrophe.
The researchers draw an important conclusion: when global warming exceeds 1 ° C, the planet has already left a safe climate state.
Destructive effects
The study indicates that reaching these tipping points will have catastrophic consequences for global climate conditions, sea levels and biodiversity. Some of them, like thawing permafrost, will release even more greenhouse gases and accelerate climate change.
But according to the study authors, while understanding of tipping points has improved over the past decade, uncertainties remain. And they estimate that if global warming exceeds 1.5°C in the coming years, some tipping points could be avoided.
Tipping points also have varying time scales. Some occur quickly: the death of coral reefs can occur in 10 years, while the sudden melting of boreal permafrost can occur over 200 years. Others, such as the collapse of Greenland’s ice sheet, can take up to 10,000 years once the processes begin, extending their effects on the global climate system and sea level over long periods of time.
” Every additional fraction of a degree we avoid above 1.5°C reduces the likelihood that further extremes will be triggered or possible. »
“I would say it’s not a situation Game over. It shows what the stakes are in that 1.5 to 2 degree range,” he adds.
Of these five hotspots, two are in Canada.
Permafrost : The Canadian case
Half of Canada is covered in permafrost, where the ground is at or below 0°C.
According to McKay, the gradual thawing of this permafrost has been a concern for some time. There is now widespread awareness of the sudden permafrost thaw that can leave its mark on local landscapes – and have major consequences for the global climate.
Permafrost contains carbon from the remains of plants and animals that died millions of years ago. Right now, this carbon is safely locked in the ground, but if the permafrost thaws, it can be released into the atmosphere and accelerate global warming.
Our understanding of this is just beginning to evolve and we estimate that it could increase emissions by 50-100%, in addition to the gradual melting.
McKay says.
A destructive cycle
Jennifer Baltzer takes a close look at the changes to the northern landscape and emphasizes the importance of protecting these soils.
” Twice as much carbon is buried in permafrost soil as there is in the atmosphere. »
As the soil warms and thaws, this carbon becomes available to soil microbes to decompose and then release carbon dioxide and methane into the atmosphere.
She continues.
It becomes a destructive cycle.
As the permafrost melts and carbon is released, the planet continues to warm, causing the permafrost to melt faster, sending more carbon into the atmosphere.
Ms. Baltzer notes that the Arctic is warming at a faster rate than the average rate recorded in the rest of the world. A 1.5°C increase in global temperature would mean a rise of four to five degrees in the Arctic. At those temperatures, he says, it becomes harder for the permafrost to maintain itself and hold that carbon.
This huge temperature increase in the Arctic drives the whole process [visant à combattre le réchauffement climatique] Even harder. It’s really essential that we stay below 1.5 degrees
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With information from CBC News’ Inayat Singh
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