Glacier the size of Florida is changing the course of human civilization – Alternet.org

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The Waita Glacier in West Antarctica is huge and is often described as the most dangerous glacier on the planet. It has also been dubbed the apocalyptic glacier. The glacier is two feet above sea level, but more importantly, it is the "safety net" of four other glaciers, with an additional rise in sea level of 10 to 13 feet. When Thwaites collapses, it will take away most of Antarctica from the West. This is not new information for those of us who follow science, for example, Eric Rignot in 2014, said the loss of Antarctica from the West is unstoppable . You can listen to an excellent 2019 interview between Rignot and Radio Eco-shock on Antarctica.

According to researchers at the University of Washington in 2014, Thwaites is already collapsing. "The simulations indicate that early-stage collapse has begun," their article notes. In addition, the Thwaites Glacier is a "pivot" for the rest of the Western Antarctic Ice Sheet; its rapid collapse "would likely impact on adjacent watersheds, thus undermining much of West Antarctica".

Thwaites glacier in 2019.

NASA's Jet Propulsion Laboratory announced last January that a huge cavity had been dug at the bottom of the glacier because of the ocean warming alarms that indicated the ice block could collapse and disintegrate the ice pack. .

It would be two-thirds the size of Manhattan and, at the height of a ten-story building, at an altitude of 1,000 feet. The new hole contained 14 billion tons of ice and NASA observed that the terrible melting and decomposition was not there just three years ago. It was NASA's Icebridge program that made this discovery possible with radar penetrating the ice, crossing the glacier several kilometers deep, as well as "data from a constellation of radars with synthetic aperture Italian and German ".

But this was just one of the terrors discovered by the satellites, which confirmed fears that "Thwaites was not attached to the rock in place."

Another element that is changing is the line of grounding of a glacier – the place near the edge of the continent where it rises and begins to float on the sea water. Many Antarctic glaciers extend on kilometers beyond their anchor lines, floating above the ocean.

Just as a stranded boat can float again when the weight of its cargo is removed, a glacier that loses weight of ice can float above the lands where it once was. When this happens, the line of stranding recedes to the interior of the land. This further exposes the bottom of a glacier to seawater, increasing the likelihood that its melting rate will accelerate.

For Thwaites, "we are discovering different withdrawal mechanisms," Millilo said. Different processes at different locations of the glacier front, of a length of 100 miles (160 km), desynchronize the rates of withdrawal from the line of stranding and ice loss.

The enormous cavity lies beneath the main glacier trunk on the west side, on the farthest side of the western Antarctic Peninsula. In this region, when the tide goes up and down, the grounding line retreats and advances over an area of ​​about 3 to 5 km. Since 1992, the glacier has been peeling off a ridge in bedrock at a constant rate of about 0.6 to 0.8 km (0.6 to 0.8 km) per year. Despite this steady rate of withdrawal from the grounding line, the melting rate on this side of the glacier is extremely high.

"On the east side of the glacier, the withdrawal of the grounding line is by small channels, perhaps a kilometer wide, like fingers that collapse under the glacier to melt it by down, "said Milillo. In this region, the rate of decline of grounding lines has doubled from about 0.6 kilometers per year between 1992 and 2011 to 1.2 kilometers per year between 2011 and 2017. Even with this accelerated decline, this glacier are lower than the west side.

With warming and rising sea levels, super storms will become a new animal. I can not understand a storm like Sandy destroying the Manhattan infrastructure every five years by 2030.

Scientists have recently returned from a two-month trip aboard the Nathanial B. Palmer to the Thwaites Glacier. Jeff Goodell of Rolling Stone Magazine was aboard the research vessel and filed some pretty interesting dispatches.

On March 3rd, Bastien Queste, oceanographer of the University of East Anglia and key member of the scientific team aboard the ship, received the WhatsApp message from a colleague back in the UK -United. She had sent him a satellite image of the Thwaites Glacier and the surrounding area of ​​West Antarctica. At the time, we had just finished our own meeting with the impressive steep blue glacier and we were a few kilometers away, mapping the seabed in front of the glacier using the ship's sonar.

During this trip, satellite imagery was essential to help scientists follow the ever-changing ice in the regions we are exploring. But the card Queste received that morning was different. He noticed dark cracks in some parts of the pack ice, floating above the sea like a huge fingernail of the glacier itself. They had never been there before. The pack ice was clearly beginning to break. Queste's first thought: "Oh, shit."

Queste knew, like everyone else, that the purpose of this research trip was to better understand the risk of Thwaites Glacier collapse, one of the most important tipping points of the Earth's climate system. Thwaites is not only big, though it is (imagine a glacier the size of Florida). But because of the way the glacier ends in deep water, as well as the inverted slope of the soil, Thwaites is vulnerable to a particularly rapid collapse. Even more troubling, Thwaites is like the cork of the wine bottle for the rest of the West Antarctic Ice Sheet. Scientists are worried that the entire ice sheet will begin to collapse, resulting in sea level rise of more than 10 feet.

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[…] In about 48 hours, a mixture of ice about 25 miles wide and 15 miles deep is cracked and dispersed in the sea. As Queste says, "a part of the glacier which is as big as the city in which I live – it had just disappeared. "

In a separate dispatch, Goodell writes:

We tagged 12 seals with a high-tech instrument that allows them to collect ocean data while diving and swimming; These hard-working seals have already completed more than 10,000 dives and recorded close to 700 reports of temperature, depth and salinity. We recovered two moorings containing important long-term oceanographic measurements. We have mapped hundreds of kilometers of seabed still unexplored with sonars. We launched and recovered underwater gliders to measure the temperature and salinity of the oceans. We did three missions with the Hugin, an automated underwater camera, which created very high resolution maps of the seabed in front of the Thwaites Glacier. We have explored ancient beaches on five isolated islands, looking for evidence of past sea-level rise in the area. And we captured 27 cores of sediment at the bottom of the sea of ​​Amundsen.

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Scientists will take a while to analyze the data we have collected and say anything definitive. But it is already clear that some of our conclusions were remarkable, even historical: we mapped a non-mapped part of the Amundsen Sea, which allowed us to better understand the seabed topography in front of Thwaites, which will help scientists understand the flow of hot water under the sea. glacier. Using high-resolution instruments installed in the Hugin, we found traces at the bottom of the seabed, probably due to the retreat of glaciers, which will greatly help researchers determine when and if the Thwaites glacier collapsed. recently. And we have collected the first direct evidence of the presence of a warm circumpolar deep water under Thwaites, as well as several hypotheses regarding the mechanism that governs it.

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I've also learned a lot about climatologists and their work. Like the rest of us, they are able to make mistakes, to push wrong assumptions and to overinterpret the data. Money matters a lot to them, but not for the critics of the climate (it's about funding research, not about ski condos in Aspen). I've learned that some scientists can read sediment cores like a book, each chapter being filled with new characters engaged in a fierce struggle to survive on our ever-changing planet. I've learned that science is not only hard work and often dangerous, but also impromptu, improvised and weather dependent. And that on a ship like the Palmer, scientists are only worth the naval technicians and the crew members who work with them. More importantly, I learned that the best scientists are radical and fearless, in a way that few outsiders can understand or appreciate. They are heroes of our time.

John Gertner of Wired magazine writes:

Anandakrishnan stood up and headed for a whiteboard to draw an image of the geometry of the glacier bed. It was a line that started with a bump on the forehead, where the glacier met the sea, and tilted gently inward. For the moment, he said, it's unclear exactly how long Thwaites will have before breaking free of his lump – his land line – and beginning a rapid decline. "It's a little hooked by the nails," he explained pointing to the bump.

Glaciers like Thwaites that end in the ocean tend to follow a well-known collapse pattern. At first, the water gnaws the pack ice from below, which weakens and dilutes it. Rather than sitting securely on the seabed, it begins to float, like a ship stranded on the sand. This exposes even more of its underwater to water, and the weakening and thinning continue. The platform, now too fragile to support its own weight, begins to sink into the sea in huge pieces. More ice goes down from the inside of the glacier, restoring what has been lost, and the whole cycle begins again: melting, dilution, breakage, withdrawal; melt, thin, break, retreat.

It's hard to find a scientist, Anandakrishnan in particular, who thinks Thwaites can avoid this fate. Because his bed rests below sea level, the water will chase him far into the land. According to Anandakrishnan, when Thwaites' anchor line begins to retreat, probably in the next few decades, she could do it fast enough. This retreat may only raise sea level modestly at first. According to radar studies, scientists believe they have detected another lump, now called Ghost Ridge, which is about 45 miles from the existing one. This is what the Anandakrishnan Ghost team will plot with its seismic experiments from the surface. Is the ridge made of wet sediment or is it firm and dry? Is it weak or high? Such esoteric differences can have extraordinary effects. According to Anandakrishnan, if his fieldwork at Thwaites gives good news, it could come from the discovery that the glacier has a chance to remain firmly stuck on the phantom ridge.

So you can think of Thwaites as a man hanging on the edge of a cliff. As he falls, he grabs a rock, a solid handle, to avoid the abyss. Of course, the rock can loosen and tragically dislodge in his hands. And then he will fall.

We are not alone in experiencing the trauma of climate change:

Thank you for reading and watching with me.

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