September 26, 2022

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Climate Change | Earth at the threshold of the five cardinal points

Review Science has published the results of a study, according to which the planet is approaching the dangerous five cardinal points (Node points) that could cause significant climate disruption… and risk creating a domino effect.

Published at 12:00 am.

Andre Duchesne

Andre Duchesne

In the Paris Agreement window

The scientific consensus suggests that current temperatures are 1.1°C warmer than pre-industrial times. The Paris Agreements aim to limit the increase in global warming to 1.5°C, with an upper limit of 2°C. However, the article Science It reveals that once 1.5°C is reached, or before the margin of error is considered, the planet may reach five tipping points of irreversible climate upheaval. “Our assessment provides strong scientific evidence to target urgent action in hopes of mitigating these changes,” the scientific summary concludes.

Five close points…

The five most likely climate disruptions of 1.5 degrees warming are melting of the Greenland ice sheet, melting of the West Antarctic ice sheet, death of tropical coral reefs, melting of northern permafrost and loss of sea ice. Barents Sea. These changes do not happen immediately. They last from a few years to a few hundred years. For example, once started, melting of the permafrost can last an average of 50 years and melting of the Greenland ice sheet is estimated to last 10,000 years.

Cow! So it’s far away!

Photo courtesy of the University of Quebec at Outais

Researcher Jerome Dubras

not at all ! It’s tomorrow! “It’s very low on a biogeochemical scale,” says Jérôme Dubras, a professor and research leader in environmental economics at the University of Quebec in Outoa. “Take the disappearance of the dinosaurs. It is attributed to a meteorite impact that disrupted Earth’s biodiversity in two million years. However, the 1.1°C increase from pre-industrial times dates back about 150 years, and we observed significant changes in climate. The pace of these changes is moving at an astonishing pace. »

Nine other reference points

Photo by Mauro Pimentel, Agence France-Presse Archives

Deforestation of the Amazon rainforest in Labria in September 2021

A study of Science It identifies a total of 16 tipping points, nine globally and seven regionally. In addition to the above events, the melting of glaciers, the loss of the Amazonian forest, the collapse of the ocean current (AMOC) plays the role of the planet’s thermostat, the northern retreat of the boreal. Forest, Sahel and end of monsoon in West Africa. Not all of these tipping points occur at once. For example, four of them are estimated to occur (with a margin of error) of 4°C warming. But there is no peace. “Ten years ago, these tipping points were estimated to occur on Earth 3 degrees Celsius warmer,” recalls Jerome Dubras. In 2019, a new study Science Nine tipping points are estimated to be triggered at 1.5°C. Now this new study says five of them have already committed to a 1.1°C planet. »

The domino effect

Photo by Maxim Shemedov, Reuters Archives

A house in a village in Sakha Republic, Russia, has collapsed under permanent snow. Melting of permafrost can lead to the release of methane and CO in astronomical amounts.2Produces many GHGs in the atmosphere.

The triggering of tipping points is particularly worrisome because it can cause a domino effect. “Overall, we can carry,” says Dominique Gravel, a professor in the Department of Biology at Université de Sherbrooke and Canada Research Chair in Integrative Ecology. “We trigger the first tipping point, which increases the warming, which triggers the second, third and others in the layer. The example of melting permafrost is instructive and worrying in this regard. “If the permafrost starts to melt, it will release huge amounts of methane and CO.2 Stored in the soil, says Mr. Even if we become carbon neutral, this feedback will be permanent. Permafrost will continue to melt and release new greenhouse gases (GHGs) into the atmosphere, which will increase temperatures. »

with Science, Guardian And the world

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