Half of the planet’s glaciers will have melted by 2100 even if humanity sticks to the targets set in the Paris Climate Agreement, according to research that finds the scale and impacts of glacial loss are greater than previously thought. At least half of this loss will occur in 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 under the current 2.7°C warming scenario, losses would be greater, with 68% of glaciers disappearing. according to the paper, published in Science. There would be almost no glaciers in central Europe, western Canada and the United States by the end of the next century if this happened.
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 floods. The study covered 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 a warming of 2.7°C, melting ice would result in a sea level rise of about 115 mm. These scenarios are up to 23% higher than previous models had estimated.
The melting of mountain glaciers is thought to contribute to more than a third from sea level rise. Much of this loss is unavoidable, but the magnitude of the loss is directly linked to rising temperatures, so action on the climate crisis is essential. The researchers wrote in the paper: “The rapid increase in glacier mass losses as global temperature rises above 1.5°C underscores the urgency of establishing more ambitious climate commitments to preserve the 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 relied on measurements of specific glaciers, and that information was then extrapolated, but now researchers could get data points on each of the planet’s 200,000 glaciers. For the first time, it gave them insight into how many people would be lost under different climate change scenarios.
The study’s lead author, Dr David Rounce, a civil and environmental engineer from Carnegie Mellon University and the University of Alaska Fairbanks, said: “This is the first time we have isolated the number of glaciers that will be lost – before there is total mass loss”. Most of the glaciers that will be lost are small, currently less than 1 km². Although they contribute less to the total volume, they are the most vulnerable to This is why the total mass loss is less – so, for example, in the 2.7C scenario, 68% of the glaciers will be lost but the relative mass is less – projected at 32%.
Small glaciers are an important source of water and sustenance for millions of people. Rounce said: “When we think of where most people see and visit glaciers, it’s really in places where they’re accessible, like central Europe, or in high mountain Asia. In these regions there are many small glaciers. They are really at the heart of the societies and economies of these places.
The lower mountain ranges such as the Alps and the Pyrenees are among the most affected. In the Alps, for example, by 2050 glaciers are expected to be on average 70% smaller, with many of the smaller ones already gone, with snow-capped peaks replaced by bare rock in some places, and with significant losses of biodiversity as a result. alpine flowers could disappear After the disappearance of the glaciers, more competitive species colonize the terrain higher up the mountain. Proglacial environments are very sensitive to global warming, and mountain species are subject to the “escalator to extinction”.
It’s not the first research to predict sea level rise from melting glaciers, but the projections are more accurate than previous models. He follows the research of 2021 who found that the rate of melting ice had doubled in the past two decades, contributing more to sea level rise than the ice sheets of Greenland or Antarctica.
Professor Antonio Ruiz de Elvira, from the University of Alcala, who was not involved in the article, said all existing evidence was consistent with the findings. He said: “The study makes much of the previous partial data more concrete.”
Highlighting the importance of glaciers, he said, “In California, the water needed to support agriculture comes directly from glaciers beginning in late July. In Spain, the disappearance of the Sierra Nevada glaciers means an almost complete reduction in water availability from that time, and the same applies to the glaciers of the Pyrenees. In India and China, they mainly depend on the Himalayan glaciers.
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