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Tag Archive: Antarctica

  1. Ice Apocalypse – Rapid collapse of Antarctic glaciers could flood coastal cities by the end of this century.

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    • High tides would creep higher, slowly burying every shoreline on the planet, flooding coastal cities and creating hundreds of millions of climate refugees. All this could play out in a mere 20 to 50 years — much too quickly for humanity to adapt.
    • Six feet of sea level rise is more likely than three feet. But if carbon emissions continue to track on something resembling a worst-case scenario, the full 11 feet of ice locked in West Antarctica might be freed up, their study showed…
    • Another recent study indicates that Pine Island’s glaciers shattered in a relatively short amount of time at the end of the last ice age.
    • A fast transition away from fossil fuels in the next few decades could be enough to put off rapid sea-level rise for centuries. That’s a decision worth countless trillions of dollars and millions of lives.

    by Eric Hothaus November 21, 2017  Read full Grist article here

    ….Land-based ice, …when it falls into the ocean, it adds to the overall volume of liquid in the seas. Thus, sea-level rise. Antarctica is a giant landmass — about half the size of Africa — and the ice that covers it averages more than a mile thick. Before human burning of fossil fuels triggered global warming, the continent’s ice was in relative balance: The snows in the interior of the continent roughly matched the icebergs that broke away from glaciers at its edges.

    Now, as carbon dioxide traps more heat in the atmosphere and warms the planet, the scales have tipped.

    A wholesale collapse of Pine Island and Thwaites would set off a catastrophe. Giant icebergs would stream away from Antarctica like a parade of frozen soldiers. All over the world, high tides would creep higher, slowly burying every shoreline on the planet, flooding coastal cities and creating hundreds of millions of climate refugees.

    All this could play out in a mere 20 to 50 years — much too quickly for humanity to adapt.

    …A study they published last year was the first to incorporate the latest understanding of marine ice-cliff instability into a continent-scale model of Antarctica. Their results drove estimates for how high the seas could rise this century sharply higher. “Antarctic model raises prospect of unstoppable ice collapse,” read the headline in the scientific journal Nature, a publication not known for hyperbole.

    Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard’s findings. But if carbon emissions continue to track on something resembling a worst-case scenario, the full 11 feet of ice locked in West Antarctica might be freed up, their study showed….

    At six feet, though, around 12 million people in the United States would be displaced, and the world’s most vulnerable megacities, like Shanghai, Mumbai, and Ho Chi Minh City, could be wiped off the map.

    At 11 feet, land currently inhabited by hundreds of millions of people worldwide would wind up underwater. South Florida would be largely uninhabitable; floods on the scale of Hurricane Sandy would strike twice a month in New York and New Jersey, as the tug of the moon alone would be enough to send tidewaters into homes and buildings…

    In a new study out last month in the journal Nature, a team of scientists from Cambridge and Sweden point to evidence from thousands of scratches left by ancient icebergs on the ocean floor, indicating that Pine Island’s glaciers shattered in a relatively short amount of time at the end of the last ice age….

    …“Every revision to our understanding has said that ice sheets can change faster than we thought,” he says. “We didn’t predict that Pine Island was going to retreat, we didn’t predict that Larsen B was going to disintegrate. We tend to look at these things after they’ve happened.”

    There’s a recurring theme throughout these scientists’ findings in Antarctica: What we do now will determine how quickly Pine Island and Thwaites collapse. A fast transition away from fossil fuels in the next few decades could be enough to put off rapid sea-level rise for centuries. That’s a decision worth countless trillions of dollars and millions of lives. “The range of outcomes,” Bassis says, “is really going to depend on choices that people make.”

    Robert M. DeConto & David Pollard. Contribution of Antarctica to past and future sea-level rise. Nature 531, 591–597 (31 March 2016). doi:10.1038/nature17145

    Matthew G. Wise et al, Evidence of marine ice-cliff instability in Pine Island Bay from iceberg-keel plough marks, Nature (2017). DOI: 10.1038/nature24458
  2. Warm air helped make 2017 ozone hole smallest since 1988

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    • Scientists said the smaller ozone hole extent in 2016 and 2017 is due to natural variability and not a signal of rapid healing.

    November 2, 2017 NASA/Goddard Space Flight Center Read full ScienceDaily article here

    Measurements from satellites this year showed the hole in Earth’s ozone layer that forms over Antarctica each September was the smallest observed since 1988, scientists have announced…

    ….The ozone hole over Antarctica is expected to gradually become less severe as chlorofluorocarbons — chlorine-containing synthetic compounds once frequently used as refrigerants — continue to decline. Scientists expect the Antarctic ozone hole to recover back to 1980 levels around 2070.

    Ozone is a molecule composed of three oxygen atoms that occurs naturally in small amounts. In the stratosphere, roughly 7 to 25 miles above Earth’s surface, the ozone layer acts like sunscreen, shielding the planet from potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and also damage plants. Closer to the ground, ozone can also be created by photochemical reactions between the sun and pollution from vehicle emissions and other sources, forming harmful smog.

    Although warmer-than-average stratospheric weather conditions have reduced ozone depletion during the past two years, the current ozone hole area is still large compared to the 1980s, when the depletion of the ozone layer above Antarctica was first detected. This is because levels of ozone-depleting substances like chlorine and bromine remain high enough to produce significant ozone loss.

  3. Intensifying winds could increase east Antarctica’s contribution to sea level rise

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    November 1, 2017 University of Texas at Austin read full ScienceDaily article here

    Totten Glacier, the largest glacier in East Antarctica, is being melted from below by warm water that reaches the ice when winds over the ocean are strong, according to research. The new findings are a cause for concern because the glacier holds more than 11 feet of sea level rise and acts as a plug that helps lock in the ice of the East Antarctic Ice Sheet.

    Chad A. Greene, Donald D. Blankenship, David E. Gwyther, Alessandro Silvano, Esmee van Wijk. Wind causes Totten Ice Shelf melt and acceleration. Science Advances, 2017; 3 (11): e1701681 DOI: 10.1126/sciadv.1701681

  4. The Antarctic ice shelf continues to crack

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    July 19 2017  read full Grist article here

    The new rift in Larsen C emerged days after a Delaware-sized iceberg broke off from the ice shelf.

    Scientists aren’t totally sure of the implications, but it seems the ice shelf isn’t quite done breaking apart yet.

    The same team of British scientists who announced last week’s birth of the humongous iceberg spotted the crack in high-resolution satellite data. The scientists noted the crack “may result in further ice shelf loss” in a blog post published Wednesday. The huge iceberg itself has already begun to break apart.

    Ice shelves are floating extensions of glaciers, so their breakup has virtually no effect on global sea levels. The worry is the new rift is heading in the general direction of the Bawden Ice Rise, which is “a crucial point of stabilization for Larsen C Ice Shelf,” according to the British team. A destabilized Larsen C could speed up the flow of its parent glaciers to the ocean, which would have a slight effect on sea levels.

  5. An Iceberg the Size of Delaware Just Broke Away From Antarctica

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    By JUGAL K. PATEL and JUSTIN GILLIS UPDATED July 12, 2017  Read full story here

    A chunk of floating ice that weighs more than a trillion metric tons broke away from the Antarctic Peninsula, producing one of the largest icebergs ever recorded and providing a glimpse of how the Antarctic ice sheet might ultimately start to fall apart.

    ….Larsen C, like two smaller ice shelves that collapsed before it, was holding back relatively little land ice, and it is not expected to contribute much to the rise of the sea. But in other parts of Antarctica, similar shelves are holding back enormous amounts of ice, and scientists fear that their future collapse could dump enough ice into the ocean to raise the sea level by many feet. How fast this could happen is unclear.

    In the late 20th century, the Antarctic Peninsula, which juts out from the main body of Antarctica and points toward South America, was one of the fastest-warming places in the world. That warming had slowed or perhaps reversed slightly in the 21st century, but scientists believe the ice is still catching up to the higher temperatures….

    The one trillion ton iceberg: Larsen C Ice Shelf rift finally breaks through

    Posted: 12 Jul 2017 08:05 AM PDT  ScienceDaily

    A one trillion tonne iceberg — one of the biggest ever recorded — has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice finally completed its path through the ice…. Whilst this new iceberg will not immediately raise sea levels, if the shelf loses much more of its area, it could result in glaciers that flow off the land behind speeding up their passage towards the ocean. This non-floating ice would have an eventual impact on sea levels, but only at a very modest rate.

  6. Scientists stunned by Antarctic rainfall and a melt area bigger than Texas

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    • An area of West Antarctica more than twice the size of California partially melted in 2016 when warm winds forced by an especially strong El Nino blew over the continent.
    • Harbinger of future in Antarctica?

    Chris Mooney Washington Post  June 15 2017  see full article here

    ….In the Antarctic summer of 2016, the surface of the Ross Ice Shelf, the largest floating ice platform on Earth, developed a sheet of meltwater that lasted for as long as 15 days in some places. The total area affected by melt was 300,000 square miles, or larger than the state of Texas, the scientists report.

    That’s bad news because surface melting could work hand in hand with an already documented trend of ocean-driven melting to compromise West Antarctica, which contains over 10 feet of potential sea level rise.

    “It provides us with a possible glimpse of the future,” said David Bromwich, an Antarctic expert at Ohio State University and one of the study’s authors. The paper appeared in Nature Communications.

    “You probably have read these analyses of West Antarctica, many people think it’s slowly disintegrating right now, and it’s mostly thought to be from the warm water eating away at the bottom of critical ice shelves,” Bromwich continued. “Well, that’s today. In the future, we could see action at the surface of these ice shelves as well from surface melting. So that makes them potentially much more unstable.”…

    From ScienceDaily: Widespread snowmelt in West Antarctica during unusually warm summer Posted: 15 Jun 2017 05:46 AM PDT

    Julien P. Nicolas et al January 2016 extensive summer melt in West Antarctica favoured by strong El Niño Nature Communications 8, Article number: 15799 (2017) doi:10.1038/ncomms15799

    Abstract: Over the past two decades the primary driver of mass loss from the West Antarctic Ice Sheet (WAIS) has been warm ocean water underneath coastal ice shelves, not a warmer atmosphere. Yet, surface melt occurs sporadically over low-lying areas of the WAIS and is not fully understood. Here we report on an episode of extensive and prolonged surface melting observed in the Ross Sea sector of the WAIS in January 2016. A comprehensive cloud and radiation experiment at the WAIS ice divide, downwind of the melt region, provided detailed insight into the physical processes at play during the event. The unusual extent and duration of the melting are linked to strong and sustained advection of warm marine air toward the area, likely favoured by the concurrent strong El Niño event. The increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events.

  7. Antarctica- miles of ice collapsing into sea

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    Antarctic Dispatches is a three-part series from the seventh continent. Written by Justin Gillis. We went to Antarctica to understand how changes to its vast ice sheet might affect the world. New York Times.

    Because the collapse of vulnerable parts of the ice sheet could raise the sea level dramatically, the continued existence of the world’s great coastal cities — Miami, New York, Shanghai and many more — is tied to Antarctica’s fate….

    Remote as Antarctica may seem, every person in the world who gets into a car, eats a steak or boards an airplane is contributing to the emissions that put the frozen continent at risk. If those emissions continue unchecked and the world is allowed to heat up enough, scientists have no doubt that large parts of Antarctica will melt into the sea.

    But they do not know exactly what the trigger temperature might be, or whether the recent acceleration of the ice means that Earth has already reached it. The question confronting society, said Richard B. Alley, a climate scientist at Pennsylvania State University, is easier to ask than to answer: “How hot is too hot?”…

    Looming Floods, Cities Threatened Part 2 May 19, 2017

    [Note: California’s coast and cities are tied to Antarctica’s fate as well.  See post with summary here and for a full pdf of the new California report see: Rising Seas in California.]

    The risk is clear: Antarctica’s collapse has the potential to inundate coastal cities across the globe.

    Over tens of millions of years, thin layers of snow falling on the continent — in many places, just a light dusting every year — were pressed into ice, burying mountain ranges and building an ice sheet more than two miles thick. Under its own weight, that ice flows downhill in slow-moving streams that eventually drop icebergs into the sea.

    If that ice sheet were to disintegrate, it could raise the level of the sea by more than 160 feet — a potential apocalypse, depending on exactly how fast it happened. Recent research suggests that if society burns all the fossil fuels known to exist, the collapse of the ice sheet will become inevitable.

    Improbable as such a large rise might sound, something similar may have already happened, and recently enough that it is still lodged in collective memory.

    In the 19th century, ethnographers realized that virtually every old civilization had some kind of flood myth in its literature.

    In the Epic of Gilgamesh, waters so overwhelm the mortals that the gods grow frightened, too. In India’s version, Lord Vishnu warns a man to take refuge in a boat, carrying seeds. In the Bible, God orders Noah to carry two of every living creature on his ark.

    “I don’t think the biblical deluge is just a fairy tale,” said Terence J. Hughes, a retired University of Maine glaciologist living in South Dakota. “I think some kind of major flood happened all over the world, and it left an indelible imprint on the collective memory of mankind that got preserved in these stories.”

  8. Antarctic central ice sheet – stable since much warmer times

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    Antarctic study shows central ice sheet is stable since milder times

    Posted: 05 May 2017 07:36 AM PDT

    Central parts of Antarctica’s ice sheet have been stable for millions of years, from a time when conditions were considerably warmer than now, research suggests…Although the discovery demonstrates the long-term stability of some parts of Antarctica’s ice sheet, scientists remain concerned that ice at its coastline is vulnerable to rising temperatures….

    …”These findings help us understand how the Antarctic Ice Sheet has evolved, and to fine-tune our models and predict its future. The preservation of old rock surfaces is testimony to the stability of at least the central parts of the Antarctic Ice Sheet — but we are still very concerned over other parts of Antarctica amid climate change.”…

    David E. Sugden, Andrew S. Hein, John Woodward, Shasta M. Marrero, Ángel Rodés, Stuart A. Dunning, Finlay M. Stuart, Stewart P.H.T. Freeman, Kate Winter, Matthew J. Westoby. The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica. Earth and Planetary Science Letters, 2017; 469: 42 DOI: 10.1016/j.epsl.2017.04.006

  9. California- new state update on sea-level rise science

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    Up to 10 ft of sea level rise possible; ice loss from West Antarctica directly impacts California

    April 26 2017  California Ocean Protection Council Full report here

    Key Findings

    1 Scientific understanding of sea-level rise is advancing at a rapid pace. Projections of future sea-level rise, especially under high emissions scenarios, have increased substantially over the last few years, primarily due to new and improved understanding of mass loss from continental ice sheets. These sea-level rise projections will continue to change as scientific understanding increases and as the impacts of local, state, national and global policy choices become manifest. New processes that allow for rapid incorporation of new scientific data and results into policy will enable state and local agencies to proactively prepare.


    2 The direction of sea level change is clear. Coastal California is already experiencing the early impacts of a rising sea level, including more extensive coastal flooding during storms, periodic tidal flooding, and increased coastal erosion.


    3 The rate of ice loss from the Greenland and Antarctic Ice Sheets is increasing. These ice sheets will soon become the primary contributor to global sea-level rise, overtaking the contributions from ocean thermal expansion and melting mountain glaciers and ice caps. Ice loss from Antarctica, and especially from West Antarctica, causes higher sea-level rise in California than the global average: for example, if the loss of West Antarctic ice were to cause global sea-level to rise by 1 foot, the associated sea-level rise in California would be about 1.25 feet…


    4 New scientific evidence has highlighted the potential for extreme sea-level rise. If greenhouse gas emissions continue unabated, key glaciological processes could cross thresholds that lead to rapidly accelerating and effectively irreversible ice loss. Aggressive reductions in greenhouse gas emissions may substantially reduce but do not eliminate the risk to California of extreme sea-level rise from Antarctic ice loss.


    5 Probabilities of specific sea-level increases can inform decisions. A probabilistic approach to sea-level rise projections, combined with a clear articulation of the implications of uncertainty and the decision-support needs of affected stakeholders, is the most appropriate approach for use in a policy setting….. These projections may underestimate the likelihood of extreme sea-level rise, particularly under high emissions scenarios, so this report also includes an extreme scenario called the H++ scenario. The probability of this scenario is currently unknown, but its consideration is important, particularly for high-stakes, long-term decisions.


    6 Current policy decisions are shaping our coastal future. Before 2050, differences in sea-level rise projections under different emissions scenarios are minor but they diverge significantly past mid-century. After 2050, sea-level rise projections increasingly depend on the trajectory of greenhouse gas emissions. For example, under the extreme H++ scenario rapid ice sheet loss on Antarctica could drive rates of sea-level rise in California above 50mm/year (2 inches/year) by the end of the century, leading to potential sea-level rise exceeding 10 feet. This rate of sea-level rise would be about 30-40 times faster than the sea-level rise experienced over the last century.


    7 Waiting for scientific certainty is neither a safe nor prudent option. High confidence in projections of sea-level rise over the next three decades can inform preparedness efforts, adaptation actions and hazard mitigation undertaken today, and prevent much greater losses than will occur if action is not taken. Consideration of high and even extreme sea levels in decisions with implications past 2050 is needed to safeguard the people and resources of coastal California.

  10. 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….