According to a study just published, Himalayan glaciers have been melting twice as fast since the beginning of this century, underscoring the threat posed by the climate crisis to the water supply for hundreds of millions of people in all of Asia.
Scientists have long tried to establish how fast global temperatures caused by burning coal, oil and gas are rising in the ice landscapes of the region known as the Earth's third pole.
The Reuters news agency reports that the new analysis, covering 40 years of satellite observations in India, China, Nepal and Bhutan, showed that glaciers have been losing the equivalent of more than 46 centimeters of vertical ice every year since 2000. That it represents double the rate between 1975 and 2000.
"This is the clearest picture yet of how quickly the Himalayan glaciers are melting in this time interval and why," said lead author of the report, Joshua Maurer, a doctoral candidate at the Earth Observatory. Lamont-Doherty of Columbia University.
Although the melting of the ice caps at the Earth's north and south poles is already destabilizing the climate system, the retreat of the Himalayan ice has more direct consequences for some 800 million people who depend on meltwater to sustain their rivers. . Seasonal runoff flows appear to be increasing for the time being as glaciers degrade.
However, scientists fear what is likely to happen over time: a gradual decline in water supplies to the densely populated floodplains in India, Pakistan and China, which could increase local and international tensions.
The new findings, which were based on declassified images from US spy satellites, were released as governments met for talks in the German city of Bonn to boost efforts to cut greenhouse gas emissions. under the 2015 Paris Agreement sponsored by the United Nations.
Global carbon emissions hit a record last year. Climate models suggest that existing promises made by governments to try to reduce the emissions curve downward have yet to achieve the rapid transformational economic change needed to prevent climate impacts from worsening by many orders of magnitude.
Although the Himalayan study, published in Science Advances, did not attempt to determine precisely how much ice had melted, Maurer said that glaciers may have lost up to a quarter of their mass in the past 40 years.
Dr. Joseph Shea, a glacial geographer at the University of Northern British Columbia, who was not involved in the study, said the findings showed that higher temperatures were affecting glaciers in the world's highest mountains.
"In the long term, this will lead to changes in the timing and magnitude of the current flow in a highly populated region," Dr. Shea said.