The red dot shows the approximate location of the Nathaniel B. Palmer research vessel each day. For Boston, it’s something the city plans to adapt to. As the ice shelf thins, it lifts away from the seafloor and loses its ability to act as a brake on the flow of ice from the continent. Recent Antarctic ice mass loss from radar interferometry and regional climate modelling. Without this pushback, the glaciers that fed the ice sheet have accelerated and thinned. (Adrienne White) None of the protections necessary to preserve coastal communities will come cheap. Rignot, E., Bamber, J. L., van den Broeke, M. R., Davis, C., Li, Y., van de Berg, W. J., & van Meijgaard, E. (2008). Warm ocean temperatures in the Weddell Sea that occurred during the same period might have caused thinning and melting on the underside of the ice shelf. Their 2016 research, which predicts how marine ice cliffs will react to atmospheric warming under a variety of future greenhouse gas scenarios, found that in a future where we quickly and radically cut greenhouse gas emissions, the West Antarctic ice sheet would be relatively stable for centuries. If every country met its Paris Agreement commitments, the world would warm to 2.7 degrees Celsius. By . Before collapse, ice shelves first undergo a period of long-term thinning and basal melting, which makes them vulnerable. Chris Mooney. “There's still a debate over what [this collapse] would look like,” Graham said. The Larsen B ice shelf collapsed and broke away from the Antarctic Peninsula during February and March, 2002—a progression observed by Terra’s Moderate-resolution Imaging Spectroradiometer (MODIS) and analyzed at the University of Colorado’s National Snow and Ice Data Center. Scambos, T. A., Bohlander, J., Shuman, C., & Skvarca, P. (2004). The grounded portion of the shelf used to push back against the glaciers, slowing them down. Once the ice shelf is gone, ice will flow into the sea unchecked. At the start of the series, the ice shelf (left) is tattooed with parallel lines of blue dots. Canada’s last fully intact ice shelf was no more. A recent study put the price tag of protecting the US from rising seas over the next two decades at more than $400 billion. The ice shelf had an area of about 290 square km (110 sq miles), in 1986. In For some communities, 2 feet of sea level rise, which would come if Thwaites Glacier melts completely, represents an existential threat. While the collapse of the Larsen B was unprecedented in terms of scale, it was not the first ice shelf on the Antarctic Peninsula to experience an abrupt break up. Is Thwaites Glacier doomed? Without the buffer of an ice shelf, the glacier’s flow accelerated, stretching and thinning the ice. In a future where carbon emissions continue unabated, warming air temperatures would force its collapse within 250 years. It is the second-largest ice shelf in the Arctic Ocean. The line marks the outer limit of the ice shelf as surveyed by Marvin in 1906 (from Bushnell 1956). “Suddenly, it was making sense with what we were seeing out of the windows.”. The icebreaker Nathaniel B. Palmer, chartered by the US National Science Foundation, is shown. Many of the bergs were too tall and narrow to float upright. Tagged: “When we have better data, better science, then we can make more informed decisions.”. Scientists studying Thwaites Glacier hope to give policymakers a better sense of just how fast sea levels might rise in coming decades, and whether it’s still possible to halt the kind of massive sea level rise it could cause, or just slow its onset. U.S. Antarctic Program scientists were in the north-western Weddell Sea investigating the sediment record in a deep glacial trough of roughly 1,000,000 square kilometres (390,000 sq mi) (twice the size of Texas or France). Credit: Drone footage courtesy Aleksandra Mazur/ University of Gothenburg. National Snow and Ice Data Center. From krill to king crabs, the collapse of a 160-square-mile portion of the Wilkins Ice Shelf in Antarctica could mean many changes for wildlife at the bottom of the world. Livable Planet. “Whether it leads directly to further changes or not, we just have to wait and see,” Larter said. I don't think anyone can, hand on heart, say which of those it is yet. Climate Change But the IPCC, too, serves up its estimates with an important caveat, stating that “the collapse of the marine-based sectors of the Antarctic ice sheet, if initiated, could cause [global mean sea level] to rise substantially above the likely range during the 21st century.”. If the entire floating ice shelf at Thwaites fractures into icebergs, what’s left at the edge of the glacier is a giant cliff of ice whose shape makes it particularly vulnerable to runaway collapse. 2. This is the last in a series, Into the Thaw: Decoding Thwaites Glacier. On the other side of the island, the most northerly in Canada, the St Patrick’s Bay ice caps completely disappeared. The collapse of the Milne Ice Shelf in a combination of satellite images taken July 30 to August 4, 2020, over Ellesmere Island, Nunavut, Canada. Thwaites’ ice shelf stabilizes the whole glacier, acting like a cork in a wine bottle to slow the seaward flow of ice from the continent’s interior. Read all of the reporting from the eight-week expedition. An ice shelf is like a floating ice plateau, fed by land-based glaciers. Roughly 90% of an ice sheet typically sits below the water line. Satellite images soon showed where these icebergs were coming from. Into the Thaw: Decoding Thwaites Glacier Thwaites’ ice shelf stabilizes the whole glacier, acting like a cork in a wine bottle to slow the seaward flow of ice from the continent’s interior. Seasonal sea ice began to form and locked most of the ice debris in place for the winter, although the April 13 image shows that a few of the largest icebergs from the southern portion of the shelf had already drifted out of the area. When the bergs tipped over, the very pure ice on the bottom side of the ice shelf was exposed. A roughly 20-mile stretch of Thwaites had fractured into mile-long icebergs that were now being blown out into the bay in front of Thwaites. Antarctica The collapse of Canada’s Milne ice shelf — the country’s last one — in a corner of the country’s Ellesmere Island, has increased fears of the Arctic region being under severe stress due to global warming.. “You'd expect it might lead to even further acceleration of flow of the glacier,” Larter said of the blowout. Although sea ice occasionally occupies the bay during cold winters, it is no substitute for the ice shelf in terms of its influence on the glaciers that once fed the Larsen B. But it is a sign of the glacier’s instability. retreating ice shelves in Antarctica are located on the Antarctic Peninsula Ice ecosystem collapse. Disintegration: Antarctic Warming Claims Another Shelf, Rapid Retreat: Ice Shelf Loss along Canada’s Ellesmere Coast, Retreating Terminus of the Jakobshavn Isbrae Glacier, NASA Goddard Space “It's another step in the [progressive] retreat,” Larter said. Distribution of supraglacial lakes in relation to wind scour zones, exposed rock, blue ice, near-surface wind speed, surface melt rate and ice shelf vulnerability to surface-melt-induced collapse. But the wide range of scenarios possible by 2100 makes planning for century’s end impossible, according to Alisha Pegan, coordinator of the city’s Climate Ready Boston program. The United Nations Intergovernmental Panel on Climate Change projects between roughly 1 1/2 to 3 feet of sea level rise under a “business as usual” carbon emissions scenario, or 1 to 2 feet if we start cutting carbon immediately and dramatically. Chris Mooney. By March 7, the shelf had disintegrated into a blue-tinged mixture (mélange) of slush and ice bergs. “There are a lot of people interested in making sure that we can do this, but I can't say for sure right now.”. The next good view of the area came on February 23; several more long and narrow ice bergs had fractured from the shelf in the south. Pacific Island nations like Kiribati, the Marshall Islands and the Maldives would be wiped off the map if the West Antarctic ice sheet were to collapse entirely. In the US, just half that amount of sea level rise could prompt a coastal exodus that would rival the great migration. The last intact ice shelf in the Canadian Arctic has collapsed. Coupled with the thinning of the glacier and its faster flow, “this [event] is one expression of the fact that Thwaites Glacier is putting more and more ice into the ocean.”. “We’d like to plan for 2100. Once the glacier has retreated to a certain point, the tall cliffs of ice may crumble under their own weight. The West Antarctic Ice Sheet sits atop bowl-shaped bedrock and the West Antarctic shelf, which includes Thwaites, stabilizes the larger ice shelf. The discovery was accidental. The city is working with communities to develop neighborhood plans focusing on solutions like raised parks along Boston Harbor that serve both as spaces for recreation and flood barriers. Some communities are going beyond these national and international projections and incorporating potential melting from Antarctica’s ice sheets into their local sea level rise estimates. Antarctica’s ice shelves, floating extensions of the ice sheet, help slow the flow of ice into the ocean. The Milne Ice Shelf in Canada lost nearly half of its area in just two days. Pure, thick ice absorbs a small amount of red light. At 11 feet, much of the city would be underwater without massive, new infrastructure projects to protect it. Other factors might have contributed to the unusually rapid and near-total disintegration of the shelf. And how fast it might happen once it starts. In Boston, much of the current downtown didn’t exist prior to the arrival of European settlers. After the 2002 Larsen B ice shelf collapse, glaciers in the embayment emptied directly into the ocean. Reporter covering climate change, energy and the environment. … Yet some find opportunities in the crisis. But even the city government isn’t sure that level of protection is possible. The Ex-Markham Ice Shelf collapsed August 2008, the Ward Hunt Ice Shelf calved two ice islands between 22 July and 24 July 2008, the entire Ex-Ayles Ice Shelf calved to form an ice … The ship is the length of a football field and dwarfs a nearby cruise ship. This means that cities and countries using IPCC data to build their own localized sea level rise projections are likewise only planning for a small amount of loss from West Antarctica, which might prove to be an underestimation. If Thwaites retreats far enough inland and reaches a certain thickness, physics dictates it will start collapsing under its own weight. “The entire embayment where we’d been working for several days was littered with icebergs.”. Then the last intact ice shelf in the Canadian Arctic, the Milne Ice Shelf, did collapse losing a chunk of ice bigger than Manhattan to the ocean. RADARSAT-1 image of the Ward Hunt Ice Shelf, 12 h 47 min (GMT), 30 August 1998. “What we didn’t realize at the time is the ice [front] was coming out to chase us out,” said Rob Larter, a marine geophysicist at the British Antarctic Survey and chief scientist on the ship. Flight Center. The city of Boston is planning for more than 3 feet of sea level rise by 2070, and between 2 and 7 feet by 2100. Scientists race against time to find out. “They filled in a lot of the [Boston] Harbor with horses and shovels,” Wormser said, “and they never contemplated sea level rise.”. Eleven feet of sea level rise, which would come from the collapse of the entire West Antarctic ice sheet, is another story entirely. Scientists fear the collapse of Thwaites Glacier could one day destabilize surrounding glaciers and eventually trigger up to 11 feet of global sea level rise. Photo-like satellite images are made by combining the satellite’s observations of red, green, and blue wavelengths of light reflected from the Earth’s surface. Boston’s affluent Back Bay neighborhood was previously a tidal bay in the city until a 19th-century land reclamation project made construction of the neighborhood possible. ECCC/ESA Copernicus/Handout via … DeConto said they are still working to identify the exact tipping point that would trigger this dramatic fracturing of the West Antarctic ice sheet, but work he presented at the American Geophysical Union meeting this past winter suggests it’s somewhere between 2-3 degrees Celsius of warming. As seasonal sea ice melted the following summer, the mélange began to drift away with the currents, and in many summers since the collapse, the bay has been completely ice free. The massive blowout of icebergs won’t itself change sea levels, as the ice that fractured off deep into the ice shelf had already been floating. World of Change. Satellite images of the western portion of the Thwaites ice front on March 2, 2019, and on March 6, 2019, after a large section of what had previously been called “ice shelf” crumbled into a flotilla of icebergs. The Milne Ice Shelf, a 4,000 years old shelf is a fragment of the former Ellesmere Ice Shelf, located in the Qikiqtaaluk Region, Nunavut, Canada. The United States’ National Climate Assessment estimates we’ll see 1-4 feet of sea level rise by 2100, citing the complicated dynamics of Greenland’s and Antarctica’s ice sheets as “the primary reason that projections of global sea level rise includes such a wide range of plausible future conditions.”. Thwaites Glacier is melting fast, and scientists fear its collapse could one day destabilize surrounding glaciers and eventually trigger up to 11 feet of global sea level rise. “How quickly can you feasibly collapse something like Thwaites?” Graham said. “You could get a domino effect of icebergs falling off of the edge of an ice sheet,” said Ali Graham, a marine geophysicist on the ship from the UK’s University of Exeter. As the surface melt ponds began to fracture the shelf, strong winds or waves might have flexed the shelf, helping to trigger a runaway break up. Following the even more spectacular collapse in 2002, the Larsen A and B glaciers experienced an abrupt acceleration, about 300% on average, and their mass loss went from 2–4 gigatonnes per year in 1996 and 2000 (a gigatonne is one billion metric tonnes), to between 22 and 40 gigatonnes per year in 2006. During the next summer thaw, scientists will watch to see if more of the ice shelf inland from the mélange starts to crumble. Methane and hydrogen sulfide associated with cold seepsis suspected as the source of the chemical energy powering the ecosystem. Significant surface melting due to warm air temperatures created melt ponds that acted like wedges; they deepened the crevasses and eventually caused the shelf to splinter. The data were obtained in SAR wide 3-beam mode during descending orbit 14720. At the start of the series, the ice shelf (left) is tattooed with parallel lines of blue dots. This big blowout confirmed that there's very little actual ice shelf left in the western part of Thwaites Glacier. The dots are pools of meltwater, and they are arranged in lines because the water drained into existing crevasses. ICE-SHELF COLLAPSE, CLIMATE CHANGE, AND HABITAT LOSS 135 Fig. West Antarctica. Scambos, T. A., Hulbe, C., Fahnestock, M., & Bohlander, J. Melting ice has made the region’s abundant mineral deposits and oil and gas reserves more accessible by ship. When certain thresholds are passed, catastrophic ice shelf disintegration through iceberg calving is initiated. The Larsen C ice shelf in Antarctica, from which a Delaware-size iceberg broke away two years ago, could be at risk of collapse. Top video: Drone footage captures the Nathaniel B. Palmer research vessel surrounded by icebergs and floating sea ice in Antarctica. Instead, much of the ice there is actually what scientists call a “mélange,” a slushy mix of icebergs and other floating bits of ice formed by fracturing at an ice front. If Thwaites collapses, much of the West Antarctic Ice Sheet could follow it into the ocean. Ice shelves collapse in response to long term environmental changes, which cause on-going thinning and shrinking. Boston, of course, is not alone, nor is it the most vulnerable. One World Bank estimate suggests more than 90 million people in just 12 developing countries would be displaced. This Antarctic ice shelf could collapse by 2020, NASA says. Follow. Beneath a thin layer of clouds, a smattering of icebergs appears in the dark, open waters of the bay (right). Many low-lying coastal cities, from the US to the Netherlands to Bangladesh, are built on land partially reclaimed from the sea. They toppled over and spread out across the bay like a neat row of books that had been knocked off a shelf. The questions swirling around the future of the West Antarctic ice sheet add to the considerable uncertainty policymakers and planners face when trying to prepare for sea level rise. The ice debris field did not become a permanent fixture in Larsen Bay. Produced by Ian Coss, Steven Davy, David Evans, Alex Newman, Anna Pratt and Peter Thomson. The northernmost section of the Larsen Ice Shelf Complex, called Larsen A, lost about 1,500 square kilometers of ice in an abrupt event in January 1995. Livable Planet Milne Ice Shelf collapse . Science Scientists aboard noticed something had changed when the research vessel tried to navigate to a spot in front of the Florida-sized glacier and was blocked by ice-choked seas. This is the last in a series of deep dives into the science and people of the Nathaniel B. Palmer’s 2019 voyage to Thwaites Glacier in West Antarctica. “I don't have an answer for that,” Pegan said when asked if it was even feasible to protect Boston from 11 feet of sea level rise. The link between climate warming and break-up of ice shelves in the Antarctic Peninsula. Scientists race against time to find out. In the near term, these changes will mean more frequent, coastal flooding in low-lying areas, including some of Boston’s most historic neighborhoods. Antarctica’s Ice Shelves May Be at Growing Risk of Collapse. “Is it over a century, over a thousand years, or can you do in a decade? Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica. By February 17, the leading edge of the C-shaped shelf had retreated about 10 kilometers (6 miles) as the shelf began to splinter. The collapse of the Larsen B Ice Shelf was captured in this series of images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between January 31 and April 13, 2002. Email. The thinning and rate of future ice‐shelf demise is notoriously unpredictable, but models suggest increased shelf‐melt and calving will become more common. The last remnant of the northern part of the Wilkins Ice Shelf collapsed in early April 2009. The front face of Thwaites glacier rises an estimated 60 to 75 feet above water in the areas where it is most intact. It was the tenth major ice shelf to collapse in recent times. “It was quite remarkable,” Larter said of the satellite images. The ultimate goal of the five-year research collaboration is to collect data — on the glacier itself, the bedrock beneath it, and the warm water melting it — that will improve models and fill in some of the unknowns about what the glacier’s collapse might look like. The collapse of the Larsen B Ice Shelf was captured in this series of images from the Moderate Resolution Imaging Spectroradiometer on NASA’s Terra satellite between January 31 and April 13, 2002. The ice shelf is stabilized by contact with the seafloor. The pale blue color is largely due to the reflection from this ice. Downtown didn’t exist prior to the Netherlands to Bangladesh, are built on land partially reclaimed from sea. And 31, reducing the last images in the Larsen B embayment, Antarctica glacier, Larter... 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