Floating Antarctic ice goes from record high to record lows

Discussion in 'Earth Science' started by paddoboy, Jul 2, 2019.

  1. paddoboy Valued Senior Member

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    https://phys.org/news/2019-07-antarctic-ice-high-lows.html

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    The amount of ice circling Antarctica is suddenly plunging from a record high to record lows, baffling scientists.

    Floating ice off the southern continent steadily increased from 1979 and hit a record high in 2014. But three years later, the annual average extent of Antarctic sea ice hit its lowest mark, wiping out three-and-a-half decades of gains—and then some, a NASA study of satellite data shows.

    In recent years, "things have been crazy," said Mark Serreze, director of the National Snow and Ice Data Center. In an email, he called the plummeting ice levels "a white-knuckle ride."

    more at link.....

    the paper:

    https://www.pnas.org/content/early/2019/06/25/1906556116

    A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic:

    Significance:


    A newly completed 40-y record of satellite observations is used to quantify changes in Antarctic sea ice coverage since the late 1970s. Sea ice spreads over vast areas and has major impacts on the rest of the climate system, reflecting solar radiation and restricting ocean/atmosphere exchanges. The satellite record reveals that a gradual, decades-long overall increase in Antarctic sea ice extents reversed in 2014, with subsequent rates of decrease in 2014–2017 far exceeding the more widely publicized decay rates experienced in the Arctic. The rapid decreases reduced the Antarctic sea ice extents to their lowest values in the 40-y record, both on a yearly average basis (record low in 2017) and on a monthly basis (record low in February 2017).

    Abstract:

    Following over 3 decades of gradual but uneven increases in sea ice coverage, the yearly average Antarctic sea ice extents reached a record high of 12.8 × 106 km2 in 2014, followed by a decline so precipitous that they reached their lowest value in the 40-y 1979–2018 satellite multichannel passive-microwave record, 10.7 × 106 km2, in 2017. In contrast, it took the Arctic sea ice cover a full 3 decades to register a loss that great in yearly average ice extents. Still, when considering the 40-y record as a whole, the Antarctic sea ice continues to have a positive overall trend in yearly average ice extents, although at 11,300 ± 5,300 km2⋅y−1, this trend is only 50% of the trend for 1979–2014, before the precipitous decline. Four of the 5 sectors into which the Antarctic sea ice cover is divided all also have 40-y positive trends that are well reduced from their 2014–2017 values. The one anomalous sector in this regard, the Bellingshausen/Amundsen Seas, has a 40-y negative trend, with the yearly average ice extents decreasing overall in the first 3 decades, reaching a minimum in 2007, and exhibiting an overall upward trend since 2007 (i.e., reflecting a reversal in the opposite direction from the other 4 sectors and the Antarctic sea ice cover as a whole).
     
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  3. paddoboy Valued Senior Member

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    Probably the best most informative doco/movie that I have seen over the last few years was the award winning "Chasing Ice"
    https://chasingice.com/
    Here is the u tube video around an hour long...If you havn't the time to watch it, it is on either Netflix or Stan....well worth watching......


     
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  5. paddoboy Valued Senior Member

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    At the other end of the globe....
    https://phys.org/news/2019-07-alaska-sea-ice-alarms-coast.html

    Melted Alaska sea ice alarms coast residents, scientists


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    This May 24, 2006, file photo shows the village of Newtok, Alaska, where the eroding bank along the Ninglick River has long been a problem for the village, 480 miles west of Anchorage. Northern Alaska coastal communities and climate scientists say sea ice disappeared far earlier than normal this spring and it's affecting wildlife. The Anchorage Daily News reported in June 2019 that ice melted because of exceptionally warm ocean temperatures. (AP Photo/Al Grillo, File)
    Sea ice along northern Alaska disappeared far earlier than normal this spring, alarming coastal residents who rely on wildlife and fish.

    The early melting has been "crazy," said Janet Mitchell of Kivalina. Hunters from her family in early June traveled more than 50 miles (80 kilometers) by boat to find bearded seals on sea ice. Bearded seals in the past could be hunted just outside the village but sea ice had receded far to the north.

    "We didn't know if we'd have our winter food," she said. "That was scary."

    The hunters ran out of gas after harvesting eight seals and a walrus. They were able to call other residents to deliver fuel, Mitchell said.

    more at link.....................
     
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