Home Science Glaciers will melt even in compliance with Paris Agreement 1.5C

Glaciers will melt even in compliance with Paris Agreement 1.5C

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If global warming continues at the current rate of 2.7°C, losses will be greater with 68% of glaciers disappearing.

Half of the planet’s glaciers will have melted by 2100, even if humanity meets the targets set in the Paris climate agreement , according to the research, the scale and impacts of glacier loss are greater than previously thought. At least half of that loss will occur over the next 30 years.

The researchers found that 49% of glaciers would disappear under the most optimistic scenario of 1.5°C warming. However, if global warming continued at the current 2.7°C warming scenario, the losses would be more significant, with 68% of glaciers disappearing, according to the article , published in Science. If that happened, there would be almost no glaciers left in central Europe, western Canada and the US by the end of the next century.

This will significantly contribute to sea level rise, threaten the water supply of up to 2 billion people and increase the risk of natural disasters such as flooding. The study looked at all glacial land ice except the Greenland and Antarctic ice sheets.

If temperature increases are limited to 1.5°C of warming, mean sea level would rise by 90 mm (3.5 inches) between 2015 and 2100, but with 2.7°C of warming, melting glaciers would cause an increase in sea level of about 115 mm. These scenarios are up to 23% larger than previous models estimated.

Melting glaciers and rising sea levels

Melting mountain glaciers are believed to contribute to more than a third of sea level rise. Much of this loss is unavoidable, but the magnitude of the loss is directly related to rising temperatures, so it is critical to act on it. climate crisis. The researchers wrote in the paper: “The rapid increase in mass losses from glaciers as global temperatures rise by more than 1.5°C underscores the urgency of more ambitious climate commitments to preserve glaciers in these mountainous regions.”

The team used two decades of satellite data to map the planet’s glaciers with greater precision than ever before. Previous models were based on measurements of specific glaciers, and that information was then extrapolated, but now researchers can get data points on each of the planet’s 200,000 glaciers. For the first time, this gave them an idea of ​​how many would be lost under different climate change scenarios.

The lead author of the study, Dr. David Rounce, civil and environmental engineer at Carnegie Mellon University and the University of Alaska Fairbanks, said: “This is the first time we’ve isolated the number of glaciers that will be lost, rather than the total mass loss.” that will be lost are small, currently less than 1 square kilometer. Although they contribute less to the total volume, they are more vulnerable to changes. This is the reason why the total mass loss is lower; For example, in the scenario of 2.7C, 68% of glaciers will be lost, but the relative mass is lower; it is expected to be 32%.

Small glaciers will disappear first

Small glaciers are an important source of water and livelihoods for millions of people. Rounce said: “When we think about where most people see and visit glaciers, it’s really in places where they are accessible, like central Europe or the high mountains of Asia. In these regions there are many smaller glaciers. They are really at the center of the societies and economies of these places.”

The lower mountain ranges, such as the Alps and the Pyrenees, are among the hardest hit. In the Alps, for example, by 2050, glaciers are predicted to be 70% smaller on average, many of the smaller ones already gone, with snowy tops replaced by bare rock in some places and with significant biodiversity losses as a result. Alpine flowers may become extinct after they fade as more competitive species colonize the terrain higher up the mountain. Proglacial environments are highly sensitive to global warming and mountainous species are subject to the “escalator to extinction”.

Research yields less-than-optimistic results

This isn’t the first research to project sea level rise due to melting glaciers, but the projections are more accurate than previous models. Continues a 2021 investigation which found that the rate of melting has doubled over the past two decades, contributing more to sea level rise than the Greenland or Antarctic ice sheets.

Professor Antonio Ruiz de Elvira of the University of Alcalá, who was not involved in the paper, said all existing evidence was consistent with the results. He said: “The study makes many of the above partial data more concrete.”

Emphasizing the importance of glaciers, he said: “In California, the water needed to sustain agriculture comes from glaciers directly starting in late July. In Spain, the disappearance of the Sierra Nevada glaciers means an almost total reduction in the availability of water from that moment on, the same happening with those of the Pyrenees. In India and China, they crucially depend on Himalayan glaciers.”

By Phoebe Weston. Article in English

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