Tag: sea ice

As the largest single chunk of melting snow and ice in the world, the massive ice sheet that covers about 80 percent of Greenland is recognized as the biggest potential contributor to rising sea levels due to glacial meltwater. Until now, however, scientists’ attention has mostly focused on the ice sheet’s aquamarine lakes — bodies of meltwater that tend to abruptly drain — and on monster chunks of ice that slide into the ocean to become icebergs. But a new UCLA-led study reveals a vast network of little-understood rivers and streams flowing on top of the ice sheet that could be responsible for at least as much, if not more, sea-level rise as the other two sources combined. When snow and ice thaw during the summer, these waterways form an intricate drainage system that captures virtually all surface runoff and is capable of flushing its entire volume in less than two days, the team found. “It’s the world’s biggest water park, with magnificent and beautiful — but deadly — rushing blue rivers cutting canyons into the ice,” said Laurence C. Smith, the study’s lead author and the chair of UCLA’s geography department. The research, published in the latest issue of Proceedings ...

According to National Snow & Ice data Center, Arctic sea ice extent remained about a standard deviation below average for the month of December. Compared to recent years, 2014 as a whole was rather unremarkable. The bigger story was the record high extents observed in the Antarctic through more than half of the year. At year’s end, Antarctic sea ice extent was again at a record high, but poised for a rapid decline as the austral summer wears on. Overview of conditions Sea ice extent in December averaged 12.52 million square kilometers (4.83 million square miles). This is 540,000 square kilometers (208,495 square miles) below the 1981 to 2010 long-term average of 13.06 million square kilometers (5.04 million square miles) and 500,000 square kilometers (193,051 square miles) above the record low for the month observed in 2010. Both Hudson Bay and Baffin Bay are now essentially completely ice covered. On the Atlantic side, recent winters have been characterized by reduced winter ice extent in the Kara and Barents seas. This is not the case for the winter of 2014 to 2015. The only two regions where extent is notably below average are in the Bering Sea and the Sea of ...

A new NOAA-led report shows that Arctic air temperatures continue to rise at more than twice the rate of global air temperatures, a phenomenon known as Arctic amplification. Increasing air and sea surface temperatures, declining reflectivity at the surface of the Greenland ice sheet, shrinking spring snow cover on land and summer ice on the ocean, and declining populations and health of some polar bear populations are among the observations released today in the Arctic Report Card 2014. “Arctic warming is setting off changes that affect people and the environment in this fragile region, and has broader effects beyond the Arctic on global security, trade, and climate,” Craig McLean, acting assistant administrator for the NOAA Office of Oceanic and Atmospheric Research, said during a press conference today at the annual American Geophysical Union Fall Meeting in San Francisco. “This year’s Arctic Report Card shows the importance of international collaboration on long-term observing programs that can provide vital information to inform decisions by citizens, policymakers and industry.” McLean joined other scientists to release the Arctic Report Card, an annual update provided since 2006, that summarizes changing conditions in the Arctic. Some 63 authors from 13 countries, United States and other nation’s federal agencies ...

The Nereid Under Ice vehicle is launched from the Alfred Wegener Institute's ice-breaker Polarstern during an expedition last summer. (Image Credit: Chris German, Woods Hole Oceanographic Institution) Scientists studying the harsh and rapidly changing Arctic environment now have a valuable new tool to advance their work—an innovative robot, designed and built at the Woods Hole Oceanographic Institution (WHOI) that is changing the way scientists can interact with and observe the polar environment. Over the past 30 years, the Arctic has warmed more than any other region on Earth. As sea ice continues to thin and melt, understanding the rapid changes going on in this sensitive part of the world and its ecosystems becomes even more crucial. The new vehicle, called Nereid Under Ice (NUI), is remotely operated by pilots aboard a surface ship via a lightweight, micro-thin, fiber-optic tether, which relays in real time environmental data, including high definition imagery of what the vehicle "sees" as it explores, maps, and gathers data beneath undisturbed sea-ice away from the disruptive impact of an ice-breaking research ship.  This real-time view allows scientists to direct the vehicle's path and collect data of interest based on their visual feedback. The approximately $3 million vehicle, which was ...

CryoSat has delivered this year's map of autumn sea-ice thickness in the Arctic, revealing a small decrease in ice volume. In a new phase for ESA's ice mission, the measurements can now also be used to help vessels navigate through the north coastal waters of Alaska, for example. Measurements made during October and November show that the volume of Arctic sea ice now stands at about 10 200 cubic km – a small drop compared to last year's 10 900 cubic km. The volume is the second-highest since measurements began in 2010, and the five-year average is relatively stable. This, however, does not necessarily indicate a turn in the long-term downward trend. "We must to take care when computing long-term trends as this CryoSat assessment is short when compared to other climate records," said Prof. Andrew Shepherd from University College London and the University of Leeds. "For reliable predictions, we should try other approaches, like considering what is forcing the changes, incorporating the CryoSat data into predictive models based on solid physics, or simply waiting until more measurements have been collected." CryoSat was designed to measure sea-ice thickness across the entire Arctic Ocean, enabling scientists to monitor accurately the overall ...

It comes as no surprise, therefore, when researchers announce as they did this past September that Arctic sea ice extent is still below normal, continuing a years-long downward trend, covering less and less of the north polar seas with a frozen crust. On the heels of that announcement, came another, a little more puzzling.  While Arctic sea ice was melting, Antarctic sea ice was at an all-time high.  In 2014, sea ice surrounding Antarctica covered more of the southern oceans than it has since satellite record began in the late 1970s. "There is no doubt that climate change is real," says Walt Meier of NASA's Goddard Space Flight Center.  "The two poles are just responding in their own unique way to the same global phenomenon." Walt Meier points out that Earth, taken as a whole, is losing sea ice. According to satellite measurements from NASA and the National Snow and Ice Data Center, the Arctic has lost an average of 20,800 square miles of sea ice a year since the late 70s.  Meanwhile, the Antarctic has gained an average of 7,300 square miles per year—not enough to balance loses at the other end of the planet. "The increase we've seen in ...

While the U.S. experienced extreme weather in November, conditions in the Arctic were fairly ordinary, according to National Snow & Ice Data Center (NSIDC). Arctic sea ice in November followed a fairly average growth pace. Ice extent was near average over much of the Arctic with only the Chukchi Sea and Davis Strait showing below average ice conditions. Overview of conditions Sea ice extent in November averaged 10.36 million square kilometers (4.00 million square miles). This is 630,000 square kilometers (243,000 square miles) below the 1981 to 2010 long-term average of 10.99 million square kilometers (4.24 million square miles) and 520,000 square kilometers (201,000 square miles) above the record low for the month observed in 2006. Arctic sea ice extent continued to increase throughout the month of November. By the end of the month, most of the Arctic Ocean was covered by ice, the exception being the Chukchi Sea that remained unusually ice free for this time of year. Ice also began to extend into Hudson Bay and Baffin Bay, although ice growth was slower than average in Davis Strait. The near-average ice conditions in the East Greenland, Barents and Kara seas have not been seen in the last few ...

University of Adelaide-led research will help pinpoint the impact of waves on sea ice, which is vulnerable to climate change, particularly in the Arctic where it is rapidly retreating. Published in the Proceedings of the Royal Society A, the research reports the first laboratory experiments testing theoretical models of wave activity in frozen oceans. "Sea ice is both an indicator and agent of climate change," says project leader Dr Luke Bennetts, Research Fellow in the School of Mathematical Sciences.   "Sea ice covering the ocean surface is white and efficiently reflects the sun's rays, keeping the oceans cool. When it melts it reveals the dark ocean beneath, which absorbs the solar radiation and becomes warmer - and that, of course, further weakens the ice.   "Waves break up the ice so that it melts more easily. In addition, exposing larger areas of the ocean surface provides a larger area for the wind to generate waves, which further promotes the breaking." To date, however, climate models haven't included the impact of waves on sea ice. In collaboration with Dr Tim Williams, of the Nansen Environment and Remote Sensing Centre in Bergen, Norway, and Professor Dany Dumont, of the University of Quebec ...

This under ice view shows the thick, jumbled structure of ice under an ice floe, which makes it very hard to dig holes through to the ocean surface. (Photo: ROV team)  Antarctic scientists have used an underwater robot to produce the first detailed three-dimensional maps of Antarctic sea ice, showing it may be thicker than previously thought. The research, published in Nature Geoscience, shows that ice floes are much thicker and more variable than previous ship-based ice drilling measurements have shown. The study was conducted during a United Kingdom-led voyage to the Weddell and Bellingshausen seas in 2010 and the Australian Antarctic Division-led Sea Ice Physics and Ecosystems eXperiment-II (SIPEX-II) in 2012. Co-lead author of the paper, Dr Guy Williams, from the Antarctic Climate and Ecosystems Cooperative Research Centre, said the ‘autonomous underwater vehicle’ (AUV) technology had proved it could accurately measure and map ice thickness in difficult to access areas. “Over the two voyages, our teams covered some 500 000 square metres and mapped 10 ice floes, providing the most comprehensive and only high resolution three-dimensional view of sea ice structure to date,” Dr Williams said. Much like its surface, the underside of sea ice is often covered with ...