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2020 SkS Weekly Climate Change & Global Warming News Roundup #22

Posted on 30 May 2020 by John Hartz

A chronological listing of news articles linked to on the Skeptical Science Facebook Page during the past week: Sun, May 24 through Sat, May 30, 2020

Editor's Choice

Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues About Future Sea Level Rise

A study of seafloor ripples suggests that ice shelves can retreat six miles per year, a quantum increase over today’s rates.

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A new study in the journal Science found that floating ice shelves can melt much more rapidly than previously thought—at a rate of about six miles per year. Credit: Massimo Rumi/Barcroft Media via Getty Images 

Climate researchers racing to calculate how fast and how high the sea level will rise found new clues on the seafloor around Antarctica. A study released today suggests that some of the continent's floating ice shelves can, during eras of rapid warming, melt back by six miles per year, far faster than any ice retreat observed by satellites.

As global warming speeds up the Antarctic meltdown, the findings "set a new upper limit for what the worst-case might be," said lead author Julian Dowdeswell, director of the Scott Polar Research Institute at the University of Cambridge.

The estimate of ice shelf retreat is based on a pattern of ridges discovered on the seafloor near the Larsen Ice Shelf. The spacing and size of the ridges suggest they were created as the floating ice shelves rose and fell with the tides while rapidly shrinking back from the ocean. In findings published today in Science, the researchers estimate that to corrugate the seafloor in this way, the ice would have retreated by more than 150 feet per day for at least 90 days.

Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues About Future Sea Level Rise by Bob Berwyn, InsideClimate News, May 28, 2020

Click here to access the entire article as originally published on the InsideClimate News website.


Articles Linked to on Facebook

Sun, May 24, 2020

Mon, May 25, 2020

Tue, May 26, 2020

Wed, May 27, 2020

Thu, May 28, 2020

Fri, May 29, 2020

Sat, May 30, 2020

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Comments

Comments 1 to 7:

  1. How can melting ice sheets raise sea levels?

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    Moderator Response:

    [DB]  Because ice sheets are based on land and are not floating.

  2. Sorry, I meant floating floating ice shelves. That is after all the topic of the above post, and the title implies that melting ice shelves will raise sea levels, which obviously on their own they can't.

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  3. Why don't you go and read the article, Slarty?

    "Ice shelves float on the ocean but they are fastened to land and act as stoppers that prevent Antarctic ice sheets that are as big as the U.S. and Mexico combined from sliding into the sea. The shelves are frozen to outcrops on the seafloor, but when they melt away from those anchor points, the flow of ice into the ocean speeds up, accelerating sea level rise."

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  4. Think of the ice shelves as brakes on a car, that act to keep the car from rolling downhill too fast.

    Remove the ice shelves/brakes and everything goes downhill faster.

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  5. Slarty Bartfast, another way of looking at it is the floating ice shelves add to sea level rise, because they are frozen fresh water originating from the land based ice sheets. Its not the same as salt water freezing which doesn't change sea level rise.

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  6. Re: [3] SirCharles

    Thank you for your comment. Yes, I read the article.

     

    Re. [5] nigelj - It doesn't matter where the sea ice comes from. The point is it is floating and so it has already elevated the sea level by displacing sea water. If it melts nothing changes. The volume of sea water it displaces when it is ice is the same volume that will be replaced with water when it melts. That is Archimedes' principle. That was my point.

    As for your claim that the ice shelves are just extensions of the ice sheets on land; if that were true (a) they wouldn't be flat, and (b) they wouldn't regrow once melted as they frequently do on a seasonal basis. See here https://earthdata.nasa.gov/learn/sensing-our-planet/unexpected-ice

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    Moderator Response:

    [DB]  As your NASA article makes clear, you are confusing/conflating sea ice with ice shelves, which are extrusions of land-based ice sheets out over the surface of the ocean.  Ice shelves may be floating or grounded upon pinning points and are often hundreds of meters thick (50-600 or more).  They do not regrow "frequently...on a seasonal basis".  Sea ice varies in thickness from 1 to a few meters and is often fully seasonal in nature in the Antarctic.

    Sea ice vs ice shelves

    Commenting upon on a matter without fully understanding it sometimes happens.  But others have already pointed out that you do not have a good understanding of this subject matter.  As a result, the skeptical thing to do would be to improve your understanding of the subject before commenting further.  Alternatively, asking for good resources to use to make that improvement in your understanding is also a good idea.

  7. Slarty Bartfast @6

    The article never said these floating ice shelves melt and thus cause sea level rise. It said (paraphrasing) the floating ice shelves melt, and as a result the land based glacier ice sheets retreat more quickly thus accelerating sea level rise. Please read the article again. 

    The ice shelves are not frozen sea water. They are not sea ice. They are just extensions of the land based glacier, so they are frozen fresh water, refer here.

    Agree to the extent that most of the melting floating ice shelves wont cause sea level rise because they have already displaced the sea water. Only the part above the ocean surface would contribute to sea level rise.

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