The loss of glacial mass has dramatically accelerated in the last 20 years and now includes nearly all the world’s glaciers, according to an international research team.
The team studied all of the world’s glaciers, numbering around 220,000, excluding the Greenland and Antarctic ice sheets. Between 2000 and 2004, glaciers collectively lost 227 gigatons of ice per year, but between 2015 and 2019, the mass lost amounted to 298 gigatons per year..
The researchers used images captured aboard NASA’s Terra satellite, which has been in orbit around Earth once every 100 minutes since 1999. A high-tech camera that records pairs of images allowed scientists to create high-resolution models. of all the world’s glaciers and their elevation over time, so that they could calculate changes in the thickness and mass of the ice.
The contraction of the Himalayan glaciers continues to accelerate, populous countries like India and Bangladesh could face water or food shortages in a few decades
Scientists have long known that glaciers have melted at a high rate since the mid-20th century. But so far, the full extent of the ice loss has only been partially measured and understood. The new study, published in Nature, cited the melting of glaciers as the cause of up to 21% of the observed rise in sea level during this period, about 0.74 millimeters per year.
A “worrying” situation
Glaciers in Alaska, Iceland, and the Alps are among the fastest melting, and it is also significant in the Pamir Mountains, the Hindu Kush, and the Himalayas. “The situation in the Himalayas is particularly worrying,” he explains. Romain Hugonnet, lead author of the study and researcher at ETH Zurich and the University of Toulouse.
“During the dry season, meltwater from glaciers is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased thaw acts as a buffer for the people living in the region, but if the contraction of the Himalayan glaciers continues to accelerate, populous countries like India and Bangladesh could face water or food shortages within a few decades. “, He said.
The researchers also identified some areas where melt rates slowed between 2000 and 2019, such as on the east coast of Greenland, in Iceland and Scandinavia. They believe this was due to a meteorological anomaly in the North Atlantic which caused higher rainfall and lower temperatures over the past decade, which has slowed the loss of ice.
The study also found that an earlier trend of glaciers in the Karakoram mountain range remaining stable or even growing was no longer the case, and that these glaciers are now losing mass as well.
Glacial avalanches
On the other hand, a investigation from European Space Agency (ESA), found that glacial avalanches they are more common than previously thought. Scientists have known for several years that glaciers can break away from mountain rock and descend into valleys at speeds of up to 300 kilometers per hour like a fluid avalanche of ice rocks.
“Using satellite data, we have now discovered that such events are more common than we could have imagined, and this could be a consequence of a changing climate,” he said. Andreas Kääb, from University of Oslo.
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