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Earth Science

Rain Falls at the Summit of Greenland Ice Sheet for First Time on Record (washingtonpost.com) 63

Posted by msmash from the closer-look dept.
Greenland just experienced another massive melt event this year. But this time, something unusual happened. It also rained at the summit of the ice sheet, [Editor's note: the link may be paywalled; alternative source] nearly two miles above sea level. From a report: Around 6 a.m. Saturday, staff at the National Science Foundation's Summit Station woke up to raindrops and water beads condensed on the station's windows. Rain occasionally falls on the ice sheet, but no staff member recalls rain -- even a light drizzle -- ever occurring at the summit before. "Basically, the entire day of Saturday, it was raining every hour that [staff] was making weather observations," said Zoe Courville, a research engineer at the Cold Regions Research and Engineering Laboratory. "And that's the first time that's been observed happening at the station."

The rain coincided with warmer temperatures that caused extensive melting across the ice sheet. Some areas were more than 18 degrees Celsius warmer than the average temperature. At the summit, temperatures peaked at 33 degrees Fahrenheit -- within a degree above freezing. The melt extent peaked at 337,000 square miles on Saturday, according to the National Snow and Ice Data Center (NSIDC). This was slightly smaller than the melting event that occurred this summer on July 28, which covered 340,000 square miles of the ice sheet, but it is still significant. Only 2012 and 2021 had multiple melt events covering more than 309,000 square miles in a year.
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Rain Falls at the Summit of Greenland Ice Sheet for First Time on Record More

Rain Falls at the Summit of Greenland Ice Sheet for First Time on Record

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  • The rainwater will fill in the crevices of the ice sheet and freeze when the ice and cooler weather freeze it, solidifying the ice.

    • Re: (Score:3, Informative)

      by jellomizer ( 103300 )

      I guess you live in an area with Warm climates, and don't understand how potholes form. Filling the cracks will be water which when frozen will expand, and push the Ice Sheets causing more and larger fractures.

      • With any other material, you would be right. With ice, yes it would expand and push it apart, but it would also bind with it. I'm really not sure if the net result would be stronger or weaker, but I think it's not necessarily as intuitive as you might think.

        • You're overthinking it.
          The binding doesn't help much when the expansion literally shatters the ice it binds to.
          Ice is not fluid. Water expands by 9% during that state change. That's a very large amount of displacement for something solid and brittle.
      • Have you never seen a Zamboni use water to repair an ice rink? It is the same principle. When the water freezes with the ice, it just expands the ice. It does not create stress forces as the water just expands out of the way of the new ice and through capillary action up along the crevices. It will strengthen the ice.

        • Re: (Score:2)

          by gtall ( 79522 )

          Unless it keeps raining. See, the rain means the temperature is warm enough to melt the ice. Temperature is funny that way.

        • That's because a Zamboni puts water about 1/8 of an inch deep ON TOP OF THE ICE, so the expansion has somewhere to go. That is way different than water seeping metres and even tens or hundreds of metres down cracks and when it refreezes and expands it has nowhere to go and puts stress on the surrounding structure. The kind of stress that brings down cliff faces and mountain sides in places. To explain it to you, that could be BIG stresses.

        • Re: (Score:2)

          by higuita ( 129722 )

          Every time a liquid change state to solid, it will release some heat, so the "old liquid" (now solid) may have a "lower temperature", but the surrounding solid will get a little hotter (higher temperature).
          So liquid water turned to ice will give heat to the surrounding ice, increasing it's temperature. If just a few drops of water, no problem if the ice far below freezing temperature... but with more water or with the ice near the freezing temperature, this is a big problem.
          Do this many times and the surro

        • It is the same principle.

          No. No it's not.

        • What if Greenland turns out not to be a flat surface like an ice rink? What then, smartypants?

        • No. That's not how it works.
          Putting a layer of water on top of ice (what a Zamboni does) with only superficial damage will indeed cap it.
          However, filling a deep crack with water and letting it freeze will put an immense amount of pressure (between 25k-115kpsi) on the ice surrounding the crack. It will shatter.

      • Re:Maybe (Score:4, Informative)

        by superdave80 ( 1226592 ) on Friday August 20, 2021 @02:20PM (#61712461)

        push the Ice Sheets causing more and larger fractures.

        As the ice sheet and the (now) frozen water are both, well frozen, I don't see how you would form larger fractures. They are both now solid ice, and will expand and contract at the same rate at this point.

        • Yes, AFTER freezing, they're a solid structure. Except now they're a solid structure that is slightly bigger than the previous solid structure, i.e. ice sheet with crevasses, since the previous opposing surfaces of the formers crevasses have now expanded from each other. You don't see how that could perhaps cause strain?
          • Strain, yes. But what would make the crevasses become bigger, if they are now filled with more ice? I suppose the ends of the cracks might become longer from the stress, but how much is this offset by most of the crack being filled now?

            • The cracks aren't "filled," the structure of the ice crystals is now discontinuous. More cracked. And next year more water will leak into those cracks. It is the difference between a solid and a liquid; it freezes, it expands, that crushes the ice around it. That doesn't make it fill in cracks; it creates new cracks, and heats the ice from the compression.

              You're being painfully stupid, Dave. Like "lets make pi = 3" level of stupid.

        • As the ice sheet and the (now) frozen water are both

          Do you think the water became frozen before filling the cracks?

    • Don't confuse the warm mongering MissInformation with pesky things like facts.
    • Maybe you could take, understand and pass a science class?

    • Sorry to disappoint you but that's not how it's going to work.

      for water to undergo the phase change from liquid to solid, aka freezing, you have to pull a lot more heat out of the liquid water than most people realize. The ice sheets in Greenland and Antarctica are already warming up, they don't have the extra capacity to sink enough heat from liquid rain to freeze it and still remain a solid it self.

      Consider;
      Put a container of pure water in a freezer set to -5C with a temp probe inserted. You can predict

      • for water to undergo the phase change from liquid to solid, aka freezing, you have to pull a lot more heat out of the liquid water than most people realize. The ice sheets in Greenland and Antarctica are already warming up, they don't have the extra capacity to sink enough heat from liquid rain to freeze it and still remain a solid it self.

        At a large enough scale, that's definitely correct.
        From the perspective of several kilometers of ice with cracks in them filling with water? They have more than enough capacity to sink the heat required for the phase change. And then some. A lot some.

  • âoeNo staff member recalls rainâ (Score:3)

    by Anonymous Coward on Friday August 20, 2021 @12:31PM (#61712077)
    That sounds very scientific.

    • Do you remember the last time you got hit by a train?

      If you did, I bet it was something that you would remember. However if you don't remember getting hit by a train, than it probably hadn't happened.

      Being that Rain is very uncommon than chances are if it did rain, people would remember it.

  • OTOH It never rains in Southern California.

    • Seems I've often heard that kind of talk before...
    • Southern California, Is a desert, Not supposed to rain there very frequently.

      • "Southern California, Is a desert, Not supposed to rain there very frequently."

        Whosh.

        • I live in the SF Bay area, Love fishing and the outdoors. Salmon, delta smelt populations are precarious dwindling; mostly because of large amounts of water that are diverted for Southern California, in some places, water now flows inland from the ocean/bay. Population sprawl in Southern California is threatening one of the largest ecosystems we have. Is frustrating every time I hear LA complaining about lack of water and the solution is always to get more water from somewhere else, They need to build loc

          • Re: (Score:2)

            by matthewd ( 59896 )

            The delta smelt are goners apparently: https://californiawaterblog.com/2021/01/10/2021-is-this-the-year-that-wild-delta-smelt-become-extinct/

      • Common misconception.

        Southeastern CA is a desert.
        Coastal southern CA is not- not by a long shot.

  • more than 100ft above sea level

    • Worst case estimates put the sea level rise at ~262 feet. And that is median sea level, factor in high tide variations and it gets worse.

      I'm already looking for a place that is at least 400+ feet above current sea level. Even if the ice doesn't melt in my lifetime my descendants will make bank off the place when it finally does.

  • One of these summers a heat dome to lodge over it for a few days now add in rain showers in summer and winter: https://www.sciencemag.org/new... [sciencemag.org]

  • On using metric and imperial in two adjacent sentences.
    Editors. Please use metric units.

  • They checked their ice cores and found that every 150 years or so it rains on the ice sheets, the last one recorded was in the 1880s. Was that from all the SUVs being driven during the US Civil War?

    This is a rare weather event, not some sign of global warming. Ice core samples prove this happened before many times over centuries. The article notes that the rain will simply freeze upon impacting the snow and add to the mass of the glacier so this is not likely to add to the rate of melt into the sea. Per

    • Learn to read, mouthbreather.

      “We now see three melting events in a decade in Greenland — and before 1990, that happened about once every 150 years. And now rainfall: in an area where rain never fell.”

      Practice until it clicks.

  • In 1997 the Sierra Nevada mountains along the California and Nevada border had a large snow pack. Then an fluke out of season rain storm came along and caused a lot of the snow to melt.

    The result was a really bad mess [onlyinyourstate.com].

    The rain was not warm, it was in fact quite cold, but it was still a liquid that triggered a phase change in the snow and turned most of the solid snow pack into a LOT of near freezing water that ended up ruining a lot of lives.

    While there might have been rain at the summit in the past this i

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