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Tag Archive: Antarctica

  1. Widespread movement of meltwater onto and across Antarctic ice shelves

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    Water is streaming across Antarctica

    Posted: 19 Apr 2017 10:17 AM PDT  full article here

    In the first such continent-wide survey, scientists have found extensive drainages of meltwater flowing over parts of Antarctica’s ice during the brief summer. Many of the newly mapped drainages are not new, but the fact they exist at all is significant; they appear to proliferate with small upswings in temperature, so warming projected for this century could quickly magnify their influence on sea level. An accompanying study looks at how such systems might influence the great ice shelves ringing the continent, which some researchers fear could collapse, bringing catastrophic sea-level rises. Both studies appear this week in the leading scientific journal Nature.

    1. Jonathan Kingslake, Jeremy C. Ely, Indrani Das, Robin E. Bell. Widespread movement of meltwater onto and across Antarctic ice shelves. Nature, 2017; 544 (7650): 349 DOI: 10.1038/nature22049
    2. Robin E. Bell, Winnie Chu, Jonathan Kingslake, Indrani Das, Marco Tedesco, Kirsty J. Tinto, Christopher J. Zappa, Massimo Frezzotti, Alexandra Boghosian, Won Sang Lee. Antarctic ice shelf potentially stabilized by export of meltwater in surface river. Nature, 2017; 544 (7650): 344 DOI: 10.1038/nature22048

    Related article: Antarctic scientists go chasing waterfalls

    The Atlantic  April 19, 2017

    The first-ever hydrological survey of Antarctica has just been completed, and it found nearly 700 streams, ponds, and waterfalls, a sprawling and active meltwater drainage system never previously documented.

    ….Willis is, in fact, engaged in a project to measure how ice shelves respond to pooling water. He and two other researchers recently spent months in Antarctica, embedding GPS units in different aspects of an ice shelf in order to sense how it torques and flexes as meltwater moves across its surface. “If that water is simply evacuated, then it could be that those ice shelves are more stable than the models currently suggest,” he told me. “But it’s still pretty speculative.”

    It’s also unclear how this research will ultimately feed sea-level models. Disintegrating ice shelves threaten to raise global oceans not because of the water they contain, but because they speed up the movement of the glaciers behind them, which are “grounded” on the Antarctic continent. If those ice floes speed up their drive to the sea, they could quickly juice sea levels.

    But even if Antarctic ice shelves wind up looking more stable, estimates of sea-level rise before 2100 are unlikely to change. Most near-term sea-level rise will come from “valley glaciers” (ice on the other six continents), thermal expansion (the ocean’s tendency to enlarge as it absorbs heat), and the rapidly eroding ice sheets of Greenland.

    Wednesday’s study shows how much there is still to be learned about the southernmost continent—and how much can still be extracted from what we already know. As part of her research, Bell later traveled to Cambridge to read the original Campbell party journals….

  2. Sea ice extent sinks to record lows at both poles

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    Posted: 22 Mar 2017 11:31 AM PDT see full ScienceDaily article here

    The Arctic sea ice maximum extent and Antarctic minimum extent are both record lows this year. Combined, sea ice numbers are at their lowest point since satellites began to continuously measure sea ice in 1979.…”There’s a lot of year-to-year variability in both Arctic and Antarctic sea ice, but overall, until last year, the trends in the Antarctic for every single month were toward more sea ice,” said Claire Parkinson, a senior sea ice researcher at Goddard. “Last year was stunningly different, with prominent sea ice decreases in the Antarctic. To think that now the Antarctic sea ice extent is actually reaching a record minimum, that’s definitely of interest


    Arctic sea ice hit a record low wintertime maximum extent in 2017. At 5.57 million square miles, it is the lowest maximum extent in the satellite record, and 455,600 square miles below the 1981 to 2010 average maximum extent.
    Credit: NASA Goddard’s Scientific Visualization Studio/L. Perkins

     

  3. Record High Temperatures in Antarctica

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    Posted: 01 Mar 2017 05:49 AM PST Science Daily  see full article here

    The World Meteorological Organization announced today new verified record high- temperatures in Antarctica, ranging from the high 60s (in Fahrenheit) to the high teens, depending on the location they were recorded in Antarctica. Knowledge and verification of such extremes are important in the study of weather patterns, climate variability and human induced change, report scientists….

    …”The polar regions of our planet have been termed the ‘canary’ in our global environment,” Cerveny said. “Because of their sensitivity to climate changes, sometimes the first influences of changes in our global environment can be seen in the north and south polar regions. Knowledge of the weather extremes in these locations therefore becomes particularly important to the entire world. The more we know of this critically important area to our environment, the more we can understand how all of our global environments are interlinked.”…

    Full details of the Antarctic high temperatures and their assessment are given in the on-line issue of Eos Earth and Space Science News of the American Geophysical Union, published on Mar. 1, 2017: https://eos.org/features/evaluating-highest-temperature-extremes-in-the-antarctic

  4. Antarctic Iceberg Size of Delaware Could Break Off in Weeks

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    CIARA O’ROURKE  Feb 9, 2017 02:50 PM ET see full article here

    Scientists are eyeing a growing crack in one of Antarctica’s ice shelves. A portion of the Larcen C shelf the size of Delaware could break off in months, or even weeks — an event that could signal the impending collapse of another of the southernmost continent’s ice shelves and an ominous sign of the impacts of a warming planet.

    While that wouldn’t contribute to sea level rise around the world, ice shelves act as breaks for the flow of land ice, which lies behind them. Without ice shelves in their paths, glaciers slide more easily into the oceans, which would push up global sea levels.

    The crack in the Larsen C shelf, already more than 100 miles long and slicing through 820 feet of ice, grew another six miles in just three weeks last month. Only 12 miles of ice connects the portion that’s at risk of breaking off from the rest of the shelf….

  5. Climate change could trigger strong sea level rise

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    International research team presents findings from frozen ‘climate archive’ of Antarctica

    Jan 5 2017  Univ of Bonn  ScienceDaily see full article here

    About 15,000 years ago, the ocean around Antarctica has seen an abrupt sea level rise of several meters. It could happen again. An international team of scientists with the participation of the University of Bonn is now reporting its findings in the magazine Scientific Reports.

    Michael E. Weber …”The changes that are currently taking place in a disturbing manner resemble those 14,700 years ago.” At that time, changes in atmospheric-oceanic circulation led to a stratification in the ocean with a cold layer at the surface and a warm layer below. Under such conditions, ice sheets melt more strongly than when the surrounding ocean is thoroughly mixed. This is exactly what is presently happening around the Antarctic….

    Iceberg in the southeastern Weddell Sea region. Credit: Photo: Dr. Michael Weber
  6. How the Antarctic Ice Sheet is affecting climate change

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    December 12, 2016  Oregon State University click here for ScienceDaily article

    Scientists have known for decades that small changes in climate can have significant impacts on the massive Antarctic Ice Sheet. Now a new study suggests the opposite also is true. An international team of researchers has concluded that the Antarctic Ice Sheet actually plays a major role in regional and global climate variability — a discovery that may also help explain why sea ice in the Southern Hemisphere has been increasing despite the warming of the rest of the Earth.

    Results of the study are being published this week in the journal Nature….”What we discovered, however, is that the ice sheet has undergone numerous pulses of variability that have had a cascading effect on the entire climate system.”

    ….”The introduction of that cold, fresh water lessens the salinity and cools the surface temperatures, at the same time, stratifying the layers of water,” Clark said. “The cold, fresh water freezes more easily, creating additional sea ice despite warmer temperatures that are down hundreds of meters below the surface.” The discovery may help explain why sea ice has expanded in the Southern Ocean despite global warming, the researchers say

    …The Antarctic Ice Sheet covers an area of more than 5 million square miles and is estimated to hold some 60 percent of all the fresh water on Earth. The east part of the ice sheet rests on a major land mass, but in West Antarctica, the ice sheet rests on bedrock that extends into the ocean at depths of more than 2,500 meters, or more than 8,000 feet, making it vulnerable to disintegration.

    Scientists estimate that if the entire Antarctic Ice Sheet were to melt, global sea levels would rise some 200 feet

    Pepijn Bakker, Peter U. Clark, Nicholas R. Golledge, Andreas Schmittner, Michael E. Weber. Centennial-scale Holocene climate variations amplified by Antarctic Ice Sheet discharge. Nature, 2016; DOI: 10.1038/nature20582

  7. Antarctica’s Ross Sea Designated as Marine Protected Area – Point Blue science contributes to major conservation victory

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    In late October, 2016, just as Point Blue’s Chief Science Officer, Dr. Grant Ballard, and colleagues left for their austral summer field work on Adélie Penguins and environmental change in Antarctica, the 24-nation Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) unanimously agreed to establish the Ross Sea as the world’s largest marine protected area.

    Working over seven years to make this conservation dream a reality, Point Blue and partners established the scientific basis for the protection of the Ross Sea, the world’s last near-pristine ocean. See here for a summary of the seminal 2012 publication led by Point Blue and here for the full list of recent publications we co-authored and presented on to leaders of CCAMLR’s member countries.

    The agreement provides that certain human activities, such as commercial fishing, will be prohibited across a vast area in order to meet a set of conservation and wildlife habitat protection goals that Point Blue helped to establish. Some concessions were made – for example, commercial fishing interests will be allowed to continue fishing within a designated zone for the long-lived Antarctic toothfish, a critical member of the Ross Sea food web. Also, many had sought for this agreement to be permanent, however a “sunset clause” allows it to be reviewed in 35 years.

    The good news is that the Ross Sea will remain relatively protected from human-driven impacts, helping to sustain thriving marine wildlife during this time of rapid climate change.  What a significant milestone for conservation.

    Please join me in congratulating Grant and his science team with a gift to Point Blue in their honor.

  8. World’s Largest Marine Reserve Created Off Antarctica- Ross Sea MPA

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    http://news.nationalgeographic.com/2016/10/ross-sea-marine-protected-area-antarctica/

    New 598,000 square-mile protected area is more than twice the size of Texas, and will protect everything from penguins to whales.

    A remote and largely pristine stretch of ocean off Antarctica received international protection on Friday, becoming the world’s largest marine reserve as a broad coalition of countries came together to protect 598,000 square miles of water.

    The new marine protected area in the Ross Sea was created by a unanimous decision of the international body that oversees the waters around Antarctica—the Commission for the Conservation of Antarctic Marine Living Resources—and was announced at the commission’s annual meeting in Tasmania. The commission comprises 24 countries, including the United States, and the European Union.

    South of New Zealand and deep in the Southern (or Antarctic) Ocean, the 1.9 million square-mile Ross Sea is sometimes called the “Last Ocean” because it is largely untouched by humans. Its nutrient-rich waters are the most productive in the Antarctic, leading to huge plankton and krill blooms that support vast numbers of fish, seals, penguins, and whales.

    Some 16,000 species are thought to call the Ross Sea home, many of them uniquely adapted to the cold environment. A 2011 study in the journal Biological Conservation called the Ross Sea “the least altered marine ecosystem on Earth,” citing intact communities of emperor and Adelie penguins, crabeater seals, orcas, and minke whales.

    The sea’s remoteness has meant it has largely escaped the heavy fishing and shipping pressure that has impacted so much of the world’s ocean, although rising prices for seafood and the low cost of fuel have made some fishermen eye the waters as potential new grounds in recent years. Some fishing already occurred there for Antarctic toothfish, a predatory fish that is sold as the highly prized Chilean sea bass.

    But fishing will no longer be allowed in 432,000 square miles of the new reserve (some toothfish fishing is expected to proceed in a specially designated zone in the remainder of the protected area). The new protection will go into force on December 1, 2017.

    The newly protected area “shows that the world can successfully cooperate on global environmental issues,” says Enric Sala, a marine biologist and National Geographic Explorer-in-Residence who leads the Pristine Seas project.

    “The Ross Sea is probably the largest ocean wilderness left on our planet,” he says. “It is the Serengeti of Antarctica, a wild place full of wildlife such as emperor penguins, leopard seals, minke whales, and killer whales. It’s one of these rare places where humans are only visitors and large animals rule.”….