The ice on earth is melting faster than it was in the mid-1990s, as new research shows, as climate change is driving global temperatures ever higher.
In total, an estimated 28 trillion tons of ice has melted from the world‘s sea ice, ice sheets and glaciers since the mid-1990s. The annual melting rate is now about 57 percent faster than three decades ago, scientists report in a study published Monday in the journal The Cryosphere.
“It was a surprise to see such a large increase in just 30 years,” said co-author Thomas Slater, a glaciologist at Leeds University in the UK.
While the situation is clear to those who rely on mountain glaciers for drinking water or who rely on winter sea ice to protect coastal homes from storms, the world‘s ice melt has begun to draw attention far from frozen regions, noted Slater.
Aside from being fascinated by the beauty of the polar regions, “people realize that even though the ice is far away, they will feel the effects of melting,” he said.
Melting land ice – on Antarctica, in Greenland, and on mountain glaciers – added enough water to the ocean over the three-decade period to raise the average global sea level by 3.5 centimeters. Ice loss from mountain glaciers accounted for 22 percent of annual ice loss, which is remarkable when you consider that it only accounts for about 1 percent of all land ice on land, Slater said.
All over the Arctic, sea ice is also shrinking to new summer lows. Last year saw the second lowest sea ice extent in more than 40 years of satellite monitoring. As the sea ice disappears, it releases dark water that absorbs solar radiation instead of reflecting it back from the atmosphere. This phenomenon, known as Arctic fortification, increases regional temperatures even further.
The global atmospheric temperature has risen by around 1.1 degrees Celsius since pre-industrial times. In the Arctic, the rate of warming has been more than twice the global average over the past 30 years.
Using satellite data from 1994 to 2017, location measurements and some computer simulations, the team of British scientists calculated that the world lost an average of 0.8 trillion tons of ice per year in the 1990s, but around 1.2 trillion tons annually in recent years.
Calculating an estimated ice loss from the world‘s glaciers, ice sheets, and polar seas is “a really interesting approach that is actually badly needed,” said geologist Gabriel Wolken of the Alaska Division of Geological and Geophysical Surveys. Wolken was a co-author of the Arctic Report Card 2020 published in December, but was not involved in the new study.
In Alaska, people are “very conscious” of ice loss, Wolken said. “You can see the changes with the human eye.”
Researcher Julienne Stroeve, of the National Snow and Ice Data Center in Boulder, Colorado, found that the study did not include a blanket of snow over land “that also has strong albedo feedback,” referring to a measure of how reflective one is Surface is.
The research also did not consider river or lake ice or permafrost, except to say that “these elements of the cryosphere have also undergone significant changes in the past few decades”.
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