Radically new scheme to prevent catastrophic rising sea levels

Glaciologist from Princeton says several engineering mega-projects can help stabilize the world's most dangerous glaciers.

Geoengineering , as its most loyal followers will tell you, is not only possible in principle - it is already working.

They say that they know this because we are already engaged in it - we just call this process global warming. Humanity annually releases billions of tons of greenhouse gases into the atmosphere, and as a result we have already created a different climate system: hotter, more humid and less docile than the one in which people have lived since the advent of agriculture.

So far, the most promising and least expensive ways of reversing these changes are also approaching the issue at the global level. Researchers talk about how airplanes can periodically spray gas in the upper atmosphere, which will not allow some of the sunlight to reach the surface of the Earth, which will cool the globe. This idea is actively discussed and is called solar geo-engineering. In August 2017, it was discussed by more than a hundred scientists at an informal conference; Harvard University opened a center for studying this issue for $ 7.5 million.

But the negative side effects of this technology are impossible to predict. It can create winning and losing regions, cooling some places and causing drought in others. What if you take a narrower approach? What if scientists can prevent one catastrophic symptom of climate change - the rapid rise of sea level, for example - without interfering again with nature?

Michael Wolovick, a postdoc on glaciology from Princeton University, believes this is possible.

For the last couple of years, Volovik has been studying the question of whether a set of highly focused geo-engineering projects could delay the rise of sea level by several centuries and give people time to adapt to climate change, and probably turn them around. He studies whether it is possible by building underwater walls next to the world's most unstable glaciers — namely, huge heaps of sand and stones stretching for miles across the seabed — to change the response of glaciers to warming the oceans and atmosphere, to sharply slow down or reverse their collapse.

If they work as planned, these huge walls can cause glaciers to remain intact 10 times longer than if they do nothing. In the simplest simulations, the presence of walls leads to the fact that a glacier that would collapse in 100 years is worth another thousand.

Volovik presented his work in December 2017 at the annual meeting of the American Geophysical Society, where I saw his work. In the next few weeks, we talked with him about this topic.

“One of the reasons why I present this project is that narrowly targeted measures can lead to better results. A wide range of solar geoengineering affects the scale of the entire planet, but the problems of this approach can also be global, ”he told me.

His proposal, which until this point has not been described in detail in the media, is to try to work with the source of the problem. Glaciers in Greenland and Antarctica, which will lead to the most rapid rise in sea level, are now relatively well restrained. Attempts to do something with them will be different from attempts to tweak a restless global weather system.

“They have a smaller geographic scale,” he said. “Get a lot more for the same money, in terms of public influence exerted by these streams of ice and glaciers.”

“We need to think about how we can solve this problem,” says Robin Bell, a professor of glaciology at Columbia University, and the recently elected president of the American Geophysical Society, an organization made up of more than 60,000 Earth science scientists.

“We, as scientists, can make individual contributions, and we also spend a lot of time trying to figure out how the Earth works,” Bell told me. She was Volovik's adviser when he wrote his doctoral thesis in Colombia. They used the radar to study how the ice sheet was curving and twisting, moving across the underlying rock.

“At the same time, I believe that he belongs to a small group of people who said - well, is there something we could do to slow down the influence of ice on climate change and change its movements in the future? She says. - For young scientists, such statements carry a certain risk, everyone wants you to do the same things that everyone else does. But someone needs to take the first steps. ”

And although Volovik spent two years studying this proposal in Princeton, his ideas remain in the theoretical field. It will take years of study before they become feasible. And even if they seem to be workers, they will not eliminate the need to reduce greenhouse gas emissions. A slowdown in sea level rise will not affect other effects of climate change — abrupt high-temperature arrivals , ten-year droughts , large-scale destruction of coral reefs .

These ideas will just give us some time, slowing the rise of the ocean level. But for 150 million people living on the coast not exceeding one and a half meters above sea level, this may be enough.

Here is a description of Volovik's idea: how it should work, scientific substantiation, expert opinion.



According to Volovik's plan, it is necessary to build what he calls “thresholds”: huge flat piles of material lying at the bottom of the sea. “Nothing particularly technically complex,” he says. “I imagine a large pile of sand or other bulk material, and possibly an outer layer of boulders, protecting it from tides and ebbs.”

Simply by building these giant walls in front of the world's most unstable glaciers, says Volovik, you can stop them from collapsing. How? The process seems counterintuitive. Volovik thresholds will not rise above the water level. These will not be the sea walls - not the dams that surround New Orleans today, restricting the movement of water. These will simply be changes in the underwater topography of the ocean floor.

However, our current understanding of the causes of the melting of the largest ice sheets suggests that these walls can actually work. “The largest vulnerability of Antarctica, which we know from a couple of decades of observations and qualitative data obtained, is not so much warm air as warm water,” Volovik said.

Today, the ocean surface near most ice sheets is rather cold. But only the upper layer of water is cold, but it is above denser and warmer water. When water moves in the oceans, it rises from middle depths and approaches the continental shelf of the Antarctic and its huge glaciers ending in the sea.

When this warm water reaches the glacier, it splashes at the base of the "ice barrier" - as scientists call the place where the front wall of the glacier is open to the sea. There, the warm ocean water corrodes and melts open ice. The water of the glacier becomes sea, the sea level rises, the glacier retreats.

And here is a key fact for future geo-engineers: with the growth of global temperatures, not all the giant glaciers of the world will melt equally. The second largest ice sheet of the world, located in Greenland, is mostly above sea level and touches the ocean at only a few points. “The Greenland Ice Sheet sticks its nose into the North Atlantic,” says Bell.

Now the warm ocean waters are corroding some of the fastest ice flows in Greenland - including the Jacobsavni glacier , which produces more icebergs than any other glacier in the world. But Greenland is also located between Canada and northern Europe, and therefore collects more warm air than its twin antipode from the other hemisphere. Approximately half of the annual mass loss of the glacier occurs due to surface melting — this happens when the air above the ice sheet becomes too warm to keep the ice.


Icebergs rising above the water of the Jakobshavnsky glacier, one of the few large glaciers in Greenland, melting due to contact with the ocean, are encountered with the sea at the end of the Illulissat ice fjord, pictured above. Volovik dreams that one of the first rapids will be built in this place.

By definition, Volovik's geoengineering proposal can only work with the melting caused by the ocean. But this is good: superficial melting occurs, albeit constantly, but slowly. Ocean melting is fast and unpredictable, and it is precisely because of it that in the 21st century most of the catastrophic rise in sea level will occur. All thanks to the Antarctic - more precisely, the unique geography of the western Antarctic ice sheet (Western Antarctic Ice Sheet, WAIS).

In the late 1950s, scientists who first marked out the southernmost continent found that the ice sheet of the western Antarctic differs from the Greenlandic one. The Greenland shield is on the underlying rock above sea level, and WAIS lies in the likeness of a giant bowl located in the Earth. Most of its underlying rock is below sea level. And all this is retained by strange physics: “Because the rock is below sea level, the ice sheet is attached to its base just because it is too thick to swim,” explained in a recent paper David Vaughan, director of the British Antarctic review.

Twenty years later, John Mercer, a glaciologist at Ohio State University, combined this unusual feature with a new idea that people warm up the globe by polluting the atmosphere with carbon dioxide. In 1978, in the journal Nature, he warned that the interaction of warm ocean water and the rocky bowl of WAIS could lead to a catastrophe.

At any glacier ending in the ocean, warm sea water corrodes and melts the barrier, due to which the sea level rises and the glacier retreats. But the WAIS bedrock has a slope towards the center of the continent - which means that most of the water in the glacier is closer to its center, since it is the highest in the center. These two facts together lead to a terrible mechanism with rapid and uncontrolled growth: with every meter to which WAIS retreats, it gives the ocean access to more water than a meter before. At the same time, during the retreat, the enormous weight of each ice stream will push it forward towards the hungry ocean.

Glaciers connecting WAIS with the ocean will not just disappear all the time. With acceleration, they will strive for their death, throwing more and more water into the ocean every ten years, until WAIS disappears completely. They will collapse and raise the level of the ocean by 4.5 meters.

It is this mechanism that tries to stop Volovik. His models say that simply by building a threshold at the bottom of the ocean, we will hold the deep warm water and not let it reach the glacier. If you reduce the amount of warm water washing the glacier barrier, it stops retreating, and sometimes even gains mass.


The Tewäts Glacier and the Pine Island Glacier overlook Amundsen Sea in West Antarctica

Take the Tewates Glacier, one of the largest ice flows in the ocean of the West Antarctic Ice Sheet, and one of the glaciers most disturbing to scientists. For now, the Touways retreats 1 km annually. When Volovik turns on his model, he first allows her to work for 100 years without building thresholds to simulate the passage of time and the onset of serious global warming. Towards the end of the run, the Thweits barrier retreats 100 km from the current position.

Then he builds a virtual threshold. “And then he stabilizes and he is able to recover,” he says. “In some cases, the Tweights grows larger than the current volume, and in these cases the barrier moves to the very threshold.”

In the most optimistic models, the ice shelves - floating ice, extending from the barrier into the sea - expands and connects with the threshold. This slows the advancement of the glacier and allows the barrier to advance.

And even in the most pessimistic scenarios — when Volovik indicates a simulated glacier to undergo erosion and destroy the threshold more quickly — humanity still has time left, as the lifetime of the glacier increases by 400-500 years.

Volvik warns that his models are rather primitive, and therefore time estimates should be considered as promising possibilities, and not as accurate predictions. “You don’t have to expect too much from the model’s timelines,” he says. “The simulated process removes many small irregularities from the bottom, and these irregularities are able to temporarily stabilize the ice barrier.”

He recommends that people concerned with the fate of the coasts build such rapids in two places. First they must be built in the fjords of the largest glaciers of Greenland, such as the Jacobshavn. Their width often does not exceed 2-3 km, and underwater drainage in them will resemble other large-scale civil engineering works, such as the Palm Islands in Dubai. Greenland is jointly managed by Denmark and the Greenland National Government, and these two organizations may decide to work together on this construction.

If the thresholds work in Greenland, then he recommends humanity to build them in the Antarctic. Politically, it will be quite difficult - Antarctic manages 53 countries - and this will go beyond any previous mega-engineering project. The part of the Tewates glacier that goes into the ocean is about 100 km wide. The glacier of the Gulf of Sosnovy Island, another unstable ice flow associated with WAIS, is approximately 40 km wide. Interested countries will have to use submarines for construction in both places, since some of the best places for this are under ice shelves floating on the surface of the sea.


Lovers of walks on rough terrain are walking along the icy slope in Antarctica at the end of January 2014

And they will have to work fast. Over the past two decades, scientists have built a whole constellation of satellite observatories over the southern continent. Their measurements confirm: the retreat of the ice of western Antarctica has already begun. The glacier is shorter, it moves faster and its mass is smaller than it was before. Full-scale is a collapse or not, it will be known only somewhere in the 2050th.

If this is a collapse, then it will most seriously affect the United States. The world's largest glaciers are so huge that they have their own gravitational field, which attracts ocean water to itself. The Atlantic and Pacific coasts are at the center of the gravitational influence of WAIS, with the result that global sea level rise in these places will be 25% more.

Over the past few years, some scientists have discovered several new mechanisms that may accelerate the collapse of WAIS. One of them is the instability of sea ice slopes. In the process of the constant retreat of glaciers, their leading edge can rise more than 600 m above the ocean floor. Ice is just not strong enough to hold such a weight. It will crumble, and debris, the size of a skyscraper, will fall into the water.

Another reason is hydraulic fracturing. With increasing air temperature in the Antarctic, floating lakes may form on the floating shelves. They are able to quickly destroy the ice beneath them, as happened in the Larsen Sea in 2002, when a piece of ice the size of Rhode Island [with Tomsk Oblast / approx. trans.] fell apart in just a few weeks. With the disappearance of the shelf, the terrestrial glaciers behind them accelerate their journey to the sea.

Not all glaciologists agree that computer models correctly describe these mechanisms. For example, in the last year, Robin Bell and his colleagues discovered a huge waterfall on the Antarctic shelf, as well as many other features suggesting that melt-water lakes do not always destroy the shelves.

But if you include this data in the model, the results are frightening. In 2013, the International Climate Change Expert Group predicted that by 2100 the sea level would not increase by more than 98 cm. And in a paper published a month ago, scientists took into account two new mechanisms and stated that by 2100 the sea level was business will grow by 146 cm. 153 million people will see the flooding of their own homes.

Rob Deconto, a climatologist at the University of Massachusetts at Amherst, says that he was skeptical about Wolovik's technology, but he understands why she should study. “I think I basically responded like this: okay, in the short term, we will slow down these processes,” he says. “And when can we decide that this is all really happening?” And is this a worthwhile international investment in engineering projects? ”

He is also worried that Volovik’s proposal is dealt with only with warm water, while his research says that warm air can lead to the appearance of lake melt water, the impact of which can be catastrophic. “In models with high emissions, there are long periods of high air temperature in the summer, and because of this - a large amount of melt water. And we know that in some conditions it is very bad for the shelf, regardless of the ocean temperature, he says.“We can save Tweets from melting from the bottom up, but what happens if the whole surface is covered with huge amounts of melt water every summer?”

Ken Caldeira, a climatologist from the Institute of Carnegie says that he would like to hear the opinions of engineers before spending his energy on this plan. “Without quantifying and consulting with engineers, this is just a thought experiment with modeling,” he wrote in an e-mail. “I do not have enough qualifications to evaluate this proposal, but I am skeptical about it.”

WAIS geo-engineering schemes have already happened in the past. Glaciologists once evaluated the idea of ​​pumping seawater into the center of Antarctica, so that it froze and reduced the risk of rising sea levels. In 2016, Katya Friler from the Potsdam Climate Research Institute and her colleagues studied this idea and found that such actions actually accelerate the movement of glaciers, using up to 7% of world energy production.

“Regarding geoengineering, I always stand for leaving fossil fuels in the ground and relying on proven, already existing technologies such as renewable energy,” Deconto wrote in an email.

So does Volovik himself. “It is important to emphasize that any geoengineering is not a substitute for a reduction plan,” he told me. “Sea-level rise is not the only negative consequence of climate change, and glacial geoengineering does nothing with thermal expansion and with the oxidation of the oceans, as well as with periods of sudden heat.”

“Besides,” he adds, “this is not forever. - The final fate of the Antarctic ice sheet is closely related to total carbon emissions. If we burn all the carbon in the earth, all of Antarctica will eventually melt. ”

Such a warning was made by all glaciologists - and it fits well with our ambiguous historical period. In almost all assessments of sea level rise, it is assumed that people will continue to burn fossil fuels at a tremendous rate, especially in the most underdeveloped parts of the world. Will this prediction come true? Events are too contradictory for this to be predicted. Consider, for example, the latest news: China may ban the use of gasoline cars, while Chinese companies continue to build coal-fired power plants. In America, carbon dioxide emissions continue to fall, and the federal government promises to open almost all coasts for oil drilling. Solar energy is the fastest growing source of energy, but India saysthat its coal-fired power plants will work "for many more decades."

In December, at the same conference where Volovik revealed his idea, Deconto presented early evidences based on modeling, from which it follows that if the world manages not to raise the global temperature by more than two degrees, we may be able to prevent the collapse of WAIS altogether. “It is possible,” he told me. “For this, you just need to take action with international coordination.”

But there are very few signs of such coordination now. And therefore, a new world appears, where global carbon emissions are high, and future geoengineers have to add new glaciers to their lists.

“It's not just about the Tweets, is it? Said Deconto. - Tweits are so often paid attention because there is a lot going on there, and we are watching him now. But there are other protruding glaciers that we observe throughout the continent. And there are other ways that ice can contribute to rising sea levels in deep reservoirs in eastern Antarctica — much bigger and stronger than WAIS. There are protruding glaciers that can react to fairly strong warming. ”

Then it will be not only in the Tewates, the Gulf of Sosnovy Island or Jacobshavn. And no mountains of sand and stones will keep the tide.