News Article | April 19, 2017
Antarctica isn’t a huge, static block of ice where very little goes on. For the first time, scientists are getting a sense of just how active the continent’s extensive network of lakes, rivers, and streams is. These bodies of water have existed for decades on Antarctica, and their meltwater affects the stability of the ice shelf underneath. That, in turn, has important implications for sea level rise. Antarctica’s landmass is surrounded by hundreds of floating ice shelves that play a key role in preventing sea levels from engulfing our coastal cities. In fact, these ice shelves keep the ground-based ice from flowing into the sea, which would raise sea levels by several feet. Scientists have long known that, in the summer, some surface ice and snow on these ice shelves melts, pooling in lakes and streams. But until now, the phenomenon was thought to be pretty rare, according to Alison Banwell at the University of Cambridge’s Scott Polar Research Institute, who wrote a comment on the new research. Today’s study, published in Nature, shows that the network of lakes and streams is actually widespread on top of many ice shelves, transporting water for up to 75 miles. Some ponds were found to be up to 50 miles long. “The fact that there are these huge rivers moving water for hundreds of kilometers, that’s even quite an exciting discovery,” lead study author Jonathan Kingslake, a glaciologist at Columbia University’s Lamont-Doherty Earth Observatory, tells The Verge. “They’re very common across the ice sheet, but we are a long way from being able to understand how they behave and how they will impact the ice sheet in the long term.” In fact, there’s a lot we don’t know about the way this meltwater interacts with the ice sheet. Lakes and ponds that form on top of the ice are thought to be dangerous. That’s because the weight of the liquid water can crack the ice; when water drains through the crevasses, it may freeze and expand, widening the cracks and fracturing the ice. This process is believed to have caused the break-up of the Larsen B Ice Shelf in 2002. But the meltwater doesn’t only collect in puddles. Today’s study shows that it also flows downhill in rivers — for miles across the continent. And another study published today, also in Nature, shows that the meltwater doesn’t necessarily weaken the ice shelf beneath. This second paper analyzed a particular region called the Nansen Ice Shelf located in West Antarctica. Here, large and complex river networks allow huge amounts of meltwater to flow off the shelf into the ocean, with a 400-foot-wide waterfall. The drainage system may be protecting the ice shelf by getting the water off the ice quickly, before its weight cracks the ice. That means the meltwater isn’t necessarily dangerous. “The meltwater acts as a jackhammer on an ice shelf is what we’ve always thought,” the lead author of the second Nature paper, Robin Bell, a polar scientist at Columbia University’s Lamont-Doherty Earth Observatory, tells The Verge. “This study suggests that we can’t just assume that if we turn up the temperature, every ice shelf will collapse.” Rather, the study suggests the process will be more complex. Scientists expect that as temperatures warm up, we’re going to see even more meltwater in Antarctica. So understanding how this water behaves and what effects it has is key for predicting what’s going to happen in this part of the world, and whether or not it’s going to affect sea level rise. In the first study, researchers analyzed satellite images from 1973 onwards, as well as aerial photos taken from 1947 onward. They found that a widespread and complicated drainage system made of lakes and rivers has existed across Antarctica for decades. Some of these streams and ponds are present as close as 375 miles from the South Pole, and at 4,300 feet above sea level. Those are areas that were thought to be clear of liquid water. Whether the amount of meltwater has actually increased in the past 70 years is impossible to tell, says Kingslake. That’s because in the past, photos of the continent were not taken as frequently as today. So you might have a photo taken in 1973, and then another one taken in 1980, with no images in between, Kingslake says. That seven-year gap doesn’t allow researchers to understand long-term trends, and calculate whether we’re seeing more meltwater. “At the moment, the initial indication is that things haven’t changed significantly,” Kingslake says. But as the planet warms up, scientists are expecting to see more ice and snow from the surface to melt and puddle up in lakes or flow in rivers. What effects this liquid water will have on the stability of the ice shelf, however, remains to be seen. “It is complicated and there are a whole bunch of processes that are really interesting and we don’t really understand,” Kingslake says. That’s why the Nature studies published today are important: they add a piece of the puzzle to figuring out how one of the largest reserve of ice on Earth works. As temperatures climb up and waters warm, all this information will be key to understand how sea levels will rise. As for how Kingslake got interested in studying Antarctica’s drainage systems, it’s all thanks to Google Earth. In 2010, he used to spend lots of time surfing the site, he says. At one point, he noticed lots of ponds on Antarctica’s ice surface. That inspired him to study more detailed satellite images and look into the widespread system of lakes and rivers dotting the continent. Today, Kingslake tells his students to never feel bad if they’re procrastinating by looking at Google Earth images. You never know what you’re going to find. “It’s not a waste of time!” he says.
News Article | April 25, 2017
The most comprehensive and high-resolution atlas of the seafloor of both Polar Regions is presented this week (Tuesday 25 April) at the European Geosciences Union General Assembly (EGU) in Vienna. Over 250 marine geologists and glaciologists from around the world have spent the last four years collating stunning seafloor and glacial landform images to publish the new Atlas of Submarine Glacial Landforms. This new compilation enables researchers to interpret the history of the Earth's large ice sheets and view how environmental change has re-shaped the continents. Thousands of square kilometres of the seafloor, covering an area the size of Great Britain, showcase a range of geological phenomena such as plough marks, scratched on the seafloor by the underwater keels of huge icebergs, and glacial lineations -- streamlined ridges up to tens of kilometres long moulded on the beds of fast-flowing glaciers. More than 35 individual landforms feature and are described, ranging from dramatic features in the East Siberian permafrost to trough-mouth fans -- enormous sediment deposits that build up at the mouths of the largest glaciers. The scientists examine the "fingerprint" of past glaciers and ice sheets on the seafloor where they have previously advanced and retreated due to changes in the Earth's climate. Dr Kelly Hogan, a geophysicist at British Antarctic Survey (BAS) and an editor of the volume, is presenting the atlas at the EGU in Vienna. She says: "It's exciting to see the atlas finally in print. It's a huge achievement to bring together all these images in a way that will enable us to interpret the polar seafloor landscape like never before. And it's a beautiful representation of what the seafloor can tell us about the past, much like a tree ring. For the first time it brings together examples of the more widely known glacial landforms. For example mega-scale glacial lineations offshore the Antarctic Peninsula but also of rare, enigmatic features like 40 km-long needle-shaped ridges in the Barents Sea and frost polygons -- raised mounds with geometric patterns -- formed in a permafrost landscape (then submerged by the sea) in the Laptev Sea, Eastern Siberia. "The value in having these beautiful exemplars in one volume is that we can now compare features from a range of locations and climatic settings (mild to extreme cold) and gain key information on past ice dynamics and ice retreat." Advances in ice-breaking research vessels and the use of state-of-the-art acoustic methods have produced high-resolution seafloor imagery from water depths of tens to thousands of metres, presenting it in a three dimensional context. Lead Editor Professor Julian Dowdeswell, who is the Director of the Scott Polar Research Institute in Cambridge University, says: "The individual glacial landforms and groups of landforms presented in the atlas cover a wide geographic spread from the coldest environments on the planet in East Antarctica to the warmest areas where ice reaches the sea like the fjords of Chile or Alaska. Most examples in the atlas were created since the last glacial about 20 000 years ago, but it also includes landforms from "ancient" glaciations. For example, glacial lineations that are several kilometres long are found across the Murzuq Basin in Libya, formed by an ice sheet that grew over Africa around 450 million years ago when the continent was sitting over the South Pole. These "ancient" glacial landforms are strikingly similar to the features we see on the seafloor around Antarctica today that were made by an expanded Antarctic Ice Sheet during the last glacial cold period." The atlas is presented at a session at the EGU 2017 science conference in Vienna, Austria on Wednesday 26 April. It was published recently as Memoir 46 of the Geological Society of London.
News Article | May 1, 2017
Ocean scientists often say that humans know more about the surface of Mars than the seafloor of Earth. Under the icy water surrounding Earth's poles, there's a hidden world of dramatic landscapes — ancient canyons, craters, hills and fields. A group of scientists has compiled a new atlas of some of those formations and released images from the collection on Tuesday (April 25) at the annual meeting of the European Geosciences Union in Vienna. The 200-plus images in the "Atlas of Submarine Glacial Landforms" reveal the "fingerprints" that past glaciers and ice sheets left on the seafloor, Kelly Hogan, a marine geophysicist with the British Antarctic Survey, told reporters during a news conference. [See Images of Hidden Landsacpes from the Underwater Atlas] In all, about 250 scientists from 20 countries contributed to the new atlas. Most of the high-resolution,3D seafloor imagery was obtained by acoustic methods like multibeam sonar, where sensors on research ships send sound signals to the seafloor and record the responses back up to the ship. "I like to think of this as remote sensing of the seafloor," Hogan said. "In the same way that satellites are moving around the globe and sending down a pulse and receiving the signal back and putting together a whole picture of the planet, this is what we're doing on the ships." But satellites in space don't have to navigate pack ice. Researchers who study the seafloor can take images of only those areas they can sail near, so thereare still a lot of blank spots in the underwater topography around the poles. The total area of the images covered in the atlas would fill a region about the size of Great Britain. Nonetheless, chief editor of the atlas, Julian Dowdeswell, director of the Scott Polar Research Institute, told Live Science that over 95 percent of the types of landforms you would find on the seabed are likely represented in the new collection. The formations include a range of geological phenomena, from the once-exposed ridges left behind by fast-moving glaciers to the squiggly plough marks that have been etched into the seafloor by the keels of massive icebergs. Studying these formations could help scientists reconstruct past climates and environments. [See Time-Lapse Photos of Retreating Glaciers] "Often these features are very well-preserved because there's no humans, there's no roads, there's no weathering," Hogan said. For example, she described a former permafrost field in the shallow Laptev Sea in Eastern Siberia that was submerged when sea levels rose at least 6,000 years ago. "What these permafrost patterns tell us is that although this area was permanently frozen during the last glacial [period], it wasn't covered by grounded ice. This tells us exactly the environmental history of that area." Retreating glaciers and ice sheets are among the biggest concerns of scientists trying to understand the effects of climate change today, and Hogan hopes the glacial history preserved underwater could help scientists predict how ice will behave under different conditions in the future. "If we can find information from the seafloor about what stabilizes ice when it retreats or about how quickly it flows over different materials on the seafloor, then it means we can contribute that knowledge to the ice sheet modelers today," she said.
Chown S.L.,Stellenbosch University |
Chown S.L.,Monash University |
Lee J.E.,Stellenbosch University |
Hughes K.A.,British Antarctic Survey |
And 25 more authors.
Science | Year: 2012
News Article | January 25, 2016
Legendary explorer Ernest Shackleton and his men boarding the boat that would take them to South Georgia. More It's been a century since Sir Ernest Shackleton led some of the first major expeditions to Antarctica, but today, medical sleuths suggest Shackleton might have had a hole in his heart, possibly explaining the health problems he had all his life. A famed explorer, Shackleton led the Nimrod Expedition of 1907 to 1909, members of which were the first people to climb Mount Erebus in Antarctica, the southernmost active volcano on Earth. But the adventurer is best known for leading the Endurance expedition 100 years ago, when his ship Endurance, the strongest vessel of its time, was crushed by sea ice off the coast of Antarctica. Although Shackleton and his crew faced near death, they all succeeded in returning home. The Endurance expedition was the third of four Antarctic expeditions that Shackleton undertook. It was also the only one during which he did not suffer a physical breakdown, according to a new paper by two doctors, retired anesthetist Ian Calder in London, and cardiologist Jan Till, of the Royal Brompton Hospital in London. [Antarctica: 100 Years of Exploration (Infographic)] Shackleton was capable of great acts of endurance — for instance, he made the first crossing of the mountains and glaciers of South Georgia without any health issues. However, during other expeditions, Shackleton alarmed his companions with repeated attacks of breathlessness and weakness, Calder and Till wrote in their study. Now, Calder and Till suggest that Shackleton's breakdowns were because of a hole in his heart. They detailed their findings Jan. 13 in the Journal of the Royal Society of Medicine. Calder began investigating Shackleton after his own experience crossing South Georgia, a remote island in the Southern Ocean. "I have always been interested in the 'heroic age' of Antarctica, the space exploration of its day," Calder told Live Science. "South Georgia is still a formidable challenge — it is so isolated, and the weather so severe. It made me more interested in Shackleton's life and death." In the new research, he and Till analyzed records held in the Scott Polar Research Institute in Cambridge, England. Diary entries made by Dr. Eric Marshall, the medical officer on the Nimrod Expedition, revealed that Shackleton had a heart murmur on two occasions, the researchers found. For instance, in an entry made on Beardmore Glacier dated Jan. 21, 1909, Marshall wrote, "[Shackleton] very unwell, walked by the sledge all day – Midday-Pulse on march thin & thready, irregular about 120." However, Shackleton recovered within a few days, and was one of the strongest members of the party by the end of the journey, marching for 30 miles to prevent the Nimrod from leaving without them. Based on Shackleton's history of attacks of breathlessness, weakness and color change, and Marshall's findings of a heart murmur and an irregular pulse, the researchers diagnosed Shackleton with a congenital atrial septal defect, or hole in his heart. Shackleton died at age 47 after arriving in South Georgia at the beginning of his fourth expedition, probably due to heart problems exacerbated by his smoking. The researchers suggested that Shackleton knew that he had something wrong with his heart — his father was a doctor, and Shackleton often avoided being examined by doctors who might have tried to prevent him from going to Antarctica. "We feel sure that he knew there was an issue with his heart, but at that time there was no way of finding out what it actually was — no EKGs, no ultrasound, no scans and so on — and absolutely no treatment even if the problem had been identified," Calder said. "His collapses were infrequent, and the alternative was to revert to the mundane, by comparison, life of a seaman." Today, about 2,000 babies are born yearly in the United States with an atrial septal defect, according to the Centers for Disease Control and Prevention. The hole in the heart's wall sometimes closes on its own. But doctors can also do surgery to repair the hole, or give medications to help treat the symptoms. "Some may feel that Sir Ernest was irresponsible in undertaking the leadership of Antarctic expeditions if he suspected a problem," Calder said in the study. "But to paraphrase Dr. Johnson, there is seldom a shortage of prudent people, whilst the great things are done by those who are prepared to take a risk. Few would deny that the quality of Shackleton's leadership during his third expedition 100 years ago was crucial to the survival of the party and remains an inspiration and example for generations to come." Follow Charles Q. Choi on Twitter @cqchoi. Follow us @livescience, Facebook & Google+. Original article on Live Science. Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Cutler N.A.,Scott Polar Research Institute |
Chaput D.L.,Smithsonian Institution |
van der Gast C.J.,UK Center for Ecology and Hydrology
Soil Biology and Biochemistry | Year: 2014
Soil microbial communities (SMCs) play a critical role in the cycling of carbon and nutrients in terrestrial ecosystems, as well as regulating plant productivity and diversity. However, very little is known about long-term (decades-centuries) structural changes in these communities. The development of aboveground-belowground linkages during century-scale succession is also poorly understood. Our study addressed this knowledge gap by investigating SMC and plant communities undergoing primary succession on an 850-year chronosequence of lava flows in Iceland. We hypothesised that communities of microfungi and bacteria would respond to progressive changes in vegetation and that SMC diversity would increase with terrain age. Soil samples were collected from three lava flows at different stages of primary succession (165, 621 and 852 years after lava flow emplacement). Plant community composition was surveyed as the samples were collected. The composition of the SMCs present in the soil was determined using amplicon pyrosequencing. The physical and chemical properties of the soil were also analysed. The results of the study indicated changes in plant and fungal communities with increasing terrain age. Distinct plant and fungal assemblages were identified on the three sites and both communities became richer and more diverse with increasing terrain age. There was also evidence to suggest the development of mycorrhizal associations on older sites. In contrast, the composition and structure of the bacterial communities did not change systematically with terrain age. Similarly, there were few changes in soil properties: SOM concentrations and pH, both of which have been demonstrated to be important to SMCs, were constant across the chronosequence. These results suggest that plant community composition is significant for fungal communities, but less relevant for bacterial communities. This finding has implications for studies of primary succession and the biogeochemical impact of vegetation change in high-latitude ecosystems. © 2013 Elsevier Ltd.
Meredith M.P.,British Antarctic Survey |
Schofield O.,Rutgers University |
Newman L.,University of Tasmania |
Urban E.,University of Delaware |
Sparrow M.,Scott Polar Research Institute
Current Opinion in Environmental Sustainability | Year: 2013
The Southern Ocean is fundamentally important to the Earth system, influencing global climate, biogeochemical and ecological cycles. Limited observations suggest the Southern Ocean is changing, yet chronic under-sampling makes the causes and consequences of such changes difficult to assess, and limits the effectiveness of any response. A Southern Ocean Observing System (SOOS) is thus being created, to facilitate integration of resources, to enhance data collection and access, and to guide the sustained development of strategic, multidisciplinary science in the Southern Ocean. Here we outline the long-term vision for this system, the gains inherent in its implementation, and how the international community can move towards achieving it. © 2013 Elsevier B.V.
Donovan A.R.,University of Cambridge |
Donovan A.R.,University of Sheffield |
Oppenheimer C.,University of Cambridge |
Bravo M.,Scott Polar Research Institute
Applied Geography | Year: 2012
This paper documents the evolution of hazard maps on the island of Montserrat, where volcanic activity has continued episodically since 1995. The paper argues that public participation can constitute political empathy, particularly where livelihoods are at stake, and can bring some order to the contested boundary between scientific risk assessment and its uptake by policymakers. This highlights that both bottom-up and top-down approaches to risk assessment are important, but also that the detailed structures within government and within science can be critical in ensuring the safety of populations, and that understanding the intricacies of local realisations of the science-policy interface is crucial to managing future hazard events. Systems that are responsive to public opinion and are transparent are more likely to win public trust. This is an important area for geographical studies combining human and physical methods, not solely in the development of maps but in the framing of their production and use. © 2012 Elsevier Ltd.
Bougamont M.,Scott Polar Research Institute |
Price S.,Los Alamos National Laboratory |
Price S.,Bristol Glaciology Center |
Christoffersen P.,Scott Polar Research Institute |
Payne A.J.,Bristol Glaciology Center
Journal of Geophysical Research: Earth Surface | Year: 2011
Predicting ice sheet mass balance is challenging because of the complex flow of ice streams. To address this issue, we have coupled a three-dimensional higher-order ice sheet model to a basal processes model where subglacial till has a plastic rheology and evolving yield stress. The model was tested for its sensitivity to regional water availability. First, with an assumed undrained bed, the ice stream oscillates between active and stagnant phases, solely as a result of thermodynamic feedbacks occurring at the ice-till interface. However, the velocity amplitude decreases over time, as insufficient basal meltwater causes the ice stream to gradually thicken and enter a slow flowing "ice sheet mode." Second, we assume that the till is able to assimilate water from a hypothetical regional hydrological system. This leads to significantly different long-term behavior, as a continuously oscillating "ice stream mode" is maintained. The extra water incorporated in the till leads to higher velocities, triggering stronger thermodynamic feedbacks between the ice and till layer. Results also suggest that fast-flowing ice streams may be modulated by till properties as a result of the duration of thermal conditions during the preceding stagnant phase. Similarly, till properties beneath stagnant ice streams are influenced by basal conditions during the preceding fast flow phase. Our findings support the inference that ice streams are strongly influenced by the presence of a regional hydrological system, underscoring the need to accurately describe the coupling between ice dynamics, basal conditions and regional subglacial hydrology in ice sheet models. © 2011 by the American Geophysical Union.
News Article | January 19, 2017
I’ve always had a passion for the ice. I’d been to Iceland seven or eight times, to Arctic Norway and to Greenland. Greenland’s contribution to global sea-level rise is about three times that of Antarctica. I saw how fast the landscape was changing and wanted to put it into a body of work. I teamed up with the Scott Polar Research Institute in Cambridge. They told me these deep blue lakes were appearing every summer in increasing numbers, higher and higher up on the ice cap. They provided me with satellite images highlighting where they tend to be. But frankly, the second I got up there I could have thrown all the maps away: there are so many lakes, it’s scary. A landscape you’d expect to be pristine white is just littered with blue. I was on the ice cap for about a week last summer, and I flew whenever the weather permitted. You get massive storms, fog cover – and then suddenly it’s clear again. But at that time of year the sun never really sets, so you can go flying at three or four in the morning and the light is perfect. Imagine sitting in a helicopter without any doors, strapped into a harness and leaning out over the Arctic ice cap. It’s not particularly comfortable. The helicopter also costs around £2,000 an hour to fly, so I ended up shooting mostly from a twin-engine plane, which only had a tiny hole in the window. That meant the pilot needed to tilt the plane at an almost 60-degree angle for me to be able to shoot vertically down. He was swearing at me a lot. The images are deliberately abstract. I didn’t want them to be documentary photographs. You have to get close to find the small, hidden details that help you to understand what you’re seeing. They’re beautiful, but what you’re looking at is climate change at its worst. My favourite is the one that looks like an eye. It’s a half-circle of concentric blues at the top of the image – it’s almost as if global warming is looking right back at you. More and more lakes are forming. THAW is at Bonhams, 101 New Bond Street , London, W1S 1SR 20 to 24 February. www.timolieber.com