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Glaciers are powerful rivers of ice that can carry rocks on their backs and grind valleys in rugged mountain ranges. But now, scientists say humans may need to think about trying to conceive of these formidable forces of nature.
According to a new paper published in The Cryosphere, glacial retreat in the Arctic and Antarctic could be the most targeted – and surprisingly least expensive – way to slow sea-level rise. a dike, or even a series of artificial seamounts against which the glacier might stick, could retain unimaginable amounts of meltwater.
Unlike the construction of dikes and dikes on the coasts of the world, technical glaciers could slow the rise in sea level at the source, leveling the playing field between rich and poor countries. [Images: Greenland’s Gorgeous Glaciers]
But the idea of glacier engineering worries some scientists, especially because of the possibility of unforeseen side effects. Valentina Roberta Barletta, a postdoctoral researcher studying ice sheet dynamics at the Technical University of Denmark, may also give the public a false sense of security.
"As a theoretical exercise, it's good, that's fine," said Barletta, who was not involved in current research, at Live Science. But, she said, "playing with the public on this stuff can be a bit dangerous."
Melt the cast iron
The authors of the new document certainly do not intend their research to be considered as an excuse to ignore the consequences of greenhouse gas emissions. For one of the authors of the study, Michael Wolovick, a postdoctoral researcher at Princeton University, who is trying to slow the flow of glaciers, will not help other disasters related to climate change, ocean acidification , droughts and floods. climb that does not come from melting ice, but seawater that grows as it warms.
But ice caps are not small potatoes, as far as climate impacts go. Unfortunately for mankind, the Antarctic ice sheet is what is called "overdependent". Its edges are anchored to the seabed which is shallower than its center. If you imagined traveling from the edge of the ice cap to the center, the seabed would move away under you. The transition point of the ice to be anchored on land afloat is called the grounding line.
The glaciers of Antarctica are its bridge between the pack ice and the ocean. As temperatures rise and glaciers melt, their grounding lines recede – and the seabed on which they retreat is deeper than where they started. This means that ice tends to float, like an ice cube in a glass, said John Moore, professor of climate change at the University of Lapland and chief scientist of the College of Global Change and Earth System Science at Beijing Normal. University. And floating ice is more likely to melt than grounded ice.
It is a positive feedback system: the more the ice melts, the more likely it will melt. If this "instability of the sea ice cap" is triggered and some scientists think it exists, even if all carbon emissions stop abruptly, the ice would still be gone, Moore added.
"Then you think," Well, do we salute the ice cap or are there alternatives? "Did he declare.
Stop glaciers
Goodbye is an unattractive option. Even a sea level rise of 1.2 meters (3.9 feet) in the next century could overwhelm the coastline and create one million climate refugees per year, the researchers wrote. Hundreds of millions of people are likely to have to relocate temporarily every year, fleeing the floods. A 2014 study in the Proceedings of the National Academy of Sciences estimated that protecting the world's coastlines would cost between $ 12 billion and $ 71 billion a year.
The outlet glaciers and ice currents that will dump all this melting water into the sea are relatively small compared to this entire coastline, said Wolovick and Moore.
"Ice currents and outlet glaciers are very important leverage points in the climate system," Wolovick said.
The researchers used a very simple computer model to determine if glacier engineering would even be possible. They considered two possible solutions: first, they could build an underwater wall that would prevent hot water from entering the base of the ice, where it could cause the most damage; secondly, they could create a series of small artificial mounds that would attack the glacier, allowing them to re-join or stop floating. These structures would be built with earth and rocks, either from the nearby seabed or perhaps from elsewhere. [Images of Melt: Earth’s Vanishing Ice]
Since there are many questions about how icebergs remove icebergs and how they slide against the bedrock, the researchers did several scenarios, modifying these variables in each of them. They chose Thwaites Glacier in Antarctica as a benchmark because it is a huge "cork" that holds back the western Antarctic ice sheet.
"The Thwaites Glacier is the biggest, the toughest," said Moore. "If it works on Thwaites, what we are really saying is that other smaller glaciers should be easy."
The researchers found that in 100% of the cases, a dike that prevented hot water from circulating near the glacier prevented Thwaites from collapsing. A dike that blocked half of the hot water worked 70% of the time. In an encouraging conclusion, 50 percent of the time, it's enough to nail the seabed with seamounts to remake the glacier without blocking the water.
Unimaginable solutions
The scenarios used in the research were very simplified, said Barletta. In the actual Antarctic, there would be many more potential feedback loops to take into account in the model. His research has shown, for example, that the seabed itself could rise as glaciers recede, relieving the weight that pushes the bedrock. In the short term, at least, the rise of the seabed could be its own anchor for retreating glaciers.
"It's pretty easy to see that [geoengineering] could have a lot of other effects than stopping a glacier, "said Barletta." If you think about all that thermal energy that is stopped, where is it going? Another glacier? Does this change the current of the ocean? What will it do? We do not know anything about it. "
Although scientists are more likely than ever to focus on Antarctica and the Arctic, there is currently less infrastructure at the poles than at the height of the cold war when the military saw them as "said Moore. Countries need to open their checkbooks again to advance research on the functioning of the ice sheet collapse, he said. If the East Antarctic ice crumbled, the world could see a sea level rise of 11 feet (3.4 m). West Antarctica contains enough ice so that the sea level reaches 19 feet. (Scientists do not expect these levels to reach 2200 or 2300 even in the worst climate change scenarios.)
"Of course, much of the knowledge we need to do this kind of work is what we need, even if we decide not to do that kind of work," Moore said.
A scheme like the one researchers have explored in the new study would be best tested on a small Greenland glacier, Moore said.
This is not the first glacial geoengineering program, said Wolovick. Other possibilities include massive seawater pumping systems that would draw water from the ocean and place it on ice patches to refreeze it. Some scientists have suggested drying schemes to try to remove seawater beneath the anchored ice base, said Wolovick, or attempts to thicken the pack ice in front of glacial outlets to reduce speed calving icebergs. But it will take decades, if not a century, before glacier geoengineering is technically possible, he said.
While these ideas do not negate the need to control carbon emissions, they represent a more sophisticated approach to geoengineering, Moore said. Rather than trying to change the atmosphere as a whole to cool the globe, geoengineers can look for targets of small size but of great value. Concerning concerns about the deliberate modification of the planet? This boat sailed, said Moore.
"We control the climate of the Earth," he said. "We must take responsibility."
Original article on Live Science.
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