Scary icicle shows scale of endangered ice caps

On Earth, the amount of ice lost each year is equal to one monstrous ice cube over six miles high looming over New York.

And this loss of ice is accelerating.

In research published Monday in the scientific journal The cryosphere, Earth scientists concluded that the planet lost 28 trillion tonnes of ice between 1994 and 2017. This means that the mass of ice was melting, like a shrinking glacier. Since the 1990s, the rate of annual ice loss has increased by 57%.

“Over the past three decades, ice has been lost from all corners of our planet,” said Andrew Shepherd, professor of Earth observation at the University of Leeds and co-author of the research.

Accelerating ice loss threatens to redraw the charts around the world, as much of that melted ice – from Greenland, Antarctica and other glaciers – flows into the ocean. Already, sea level has risen by about eight to nine inches since 1880. Yet if this current rate of accelerating ice loss continues, the planet’s sea level could rise by 27 to 31 inches (about 70 to 80 cm) by the end of the century. explained Bob Kopp, director of the Institute for Earth, Ocean and Atmospheric Sciences at Rutgers University. Kopp was not involved in the study.

For much of the 20th century, sea level rose annually by about 1.4 millimeters per year. But in recent years, that figure has grown to 3.6 millimeters. “It’s accelerating,” Kopp said.

To visualize the extent of ice loss over the past several decades, ice cap researchers collaborated with graphics company Planetary Visions to produce (to scale) an image of a huge ice cube deposited next to New York. This 10 kilometer (6.2 mile) block represents the average ice loss each year since the 1990s.

Earth’s dramatic ice loss has been widely revealed by modern satellites. These satellites, some of which zoom in on the poles, document changes in difficult and inaccessible places, particularly in Greenland and Antarctica. “It’s amazing how far we’ve come in a generation,” Shepherd said, pointing to the relatively limited number of satellites in the early ’90s.

Greenland and Antarctica, home to the planet’s two largest ice caps, are expected to be the main contributors to sea level rise in the decades to come. Over the past 30 years, the loss of ice in Greenland and Antarctica has already multiplied by six. These isolated ice-covered lands are of deep concern to Earth scientists because they have the potential several feet sea ​​level rise.

“Ice has been lost from every corner of our planet.”

Greenland, for example, is now affected by warming both on land and in the oceans. Over the past two decades, warmer air temperatures have melted the ice in Greenland at an “unusual” rate. Meanwhile, an ongoing NASA mission has revealed that warming oceans are also playing a dominant role in the melting of Greenland. In research also published on Monday, this time in the journal Scientific advances, scientists show that some of Greenland’s giant glaciers, which flow to the sea in steep coves, are almost half of ice loss in Greenland occurred between 1992 and 2017.

This group of deep glaciers (79 in all), including the colossal Jakobshavn Glacier, can reach some 3,000 feet below the ocean’s surface. Here, relatively warmer waters eat away at the ice. Eventually, large chunks of serpentine glaciers break away in the ocean, adding to the rise in sea level.

“There are a small number of deep glaciers that are the big dogs,” explained NASA oceanographer Josh Willis, who heads missions in Greenland and is a co-author of the new Greenland research. “They are the most connected to the ocean.”

The oceans, which are now steadily warming, show no signs of slowing their impact on Greenland’s ice. This is one of the reasons why estimates of sea level rise at the end of the century (which in their best cases range from about one to two feet and in their worst cases range from about two feet to potentially more than three feet) from the UN Climate Science Agency. , the Intergovernmental Panel on Climate Change, are sometimes viewed as conservative. Most forecasts of sea level rise, for example, do not yet take into account the oversized impact of the ocean on Greenland. Yet there are colossal amounts of ice left for the seas to melt. We could see massive and permanent flooding of the coasts.

“Large ice caps may continue to accelerate [melting] for a long time, “said Willis of NASA.” There is a lot of ice there. “

During this time, the Earth is experiencing dramatic losses of sea ice, which plays a much smaller role in sea level rise than melting glaciers, but contributes to global warming. Today, arctic sea ice is a shell of itself: it has been declining sharply for 40 years. When shiny, reflective sea ice melts, it lets dark oceans absorb more sunlight, which in turn helps amplify warming in the Arctic. It’s a vicious circle.

See also: Where to see the dying glaciers

The overall picture is clear. The melting ice will almost certainly accelerate in many parts of the world unless humanity halt the continuing warming trend of the Earth.

“He disappears,” Willis said. “It is happening faster and faster every decade.”

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