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Earth Science

Greenland's Ice Sheet Melting Seven Times Faster Than In 1990s (theguardian.com) 282

An anonymous reader quotes a report from The Guardian: Greenland's ice sheet is melting much faster than previously thought, threatening hundreds of millions of people with inundation and bringing some of the irreversible impacts of the climate emergency much closer. Ice is being lost from Greenland seven times faster than it was in the 1990s, and the scale and speed of ice loss is much higher than was predicted in the comprehensive studies of global climate science by the Intergovernmental Panel on Climate Change, according to data. That means sea level rises are likely to reach 67cm by 2100, about 7cm more than the IPCC's main prediction. Such a rate of rise will put 400 million people at risk of flooding every year, instead of the 360 million predicted by the IPCC, by the end of the century.

Greenland has lost 3.8 trillion tons of ice since 1992, and the rate of ice loss has risen from 33 billion tons a year in the 1990s to 254 billion tons a year in the past decade. Greenland's ice contributes directly to sea level rises as it melts because it rests on a large land mass, unlike the floating sea ice that makes up much of the rest of the Arctic ice cap. About half of the ice loss from Greenland was from melting driven by air surface temperatures, which have risen much faster in the Arctic than the global average, and the rest was from the speeding up of the flow of ice into the sea from glaciers, driven by the warming ocean. The scale and speed of the ice loss surprised the team of 96 polar scientists behind the findings, published on Tuesday in the journal Nature. The Ice Sheet Mass Balance Inter-comparison Exercise comprised 26 separate surveys of Greenland from 1992 to 2018, with data from 11 different satellites and comparisons of volume, flow and gravity compiled by experts from the UK, Nasa in the US, and the European Space Agency.

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Greenland's Ice Sheet Melting Seven Times Faster Than In 1990s

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  • Some Context (Score:5, Insightful)

    by SuperKendall ( 25149 ) on Tuesday December 10, 2019 @10:40PM (#59506666)

    Even at these accelerated rates, you're looking at a loss of maybe 1-2% of Greenland's ice over a century...

    • Re:Some Context (Score:5, Interesting)

      by Waffle Iron ( 339739 ) on Tuesday December 10, 2019 @11:09PM (#59506702)

      Even at these accelerated rates, you're looking at a loss of maybe 1-2% of Greenland's ice over a century...

      That's assuming that the rate doesn't *continue* to accelerate, which it certainly will if we keep the status quo of accelerating greenhouse gas emissions.

      On top of that, many experts suspect that there may be positive feedback mechanisms that will kick in as the ice disintegrates, which will cause the melting to accelerate even faster than would be expected from just temperature changes.

      Not to mention, some people would like the human race to endure longer than just one more century.

      • Re: (Score:2, Troll)

        by phantomfive ( 622387 )

        That's assuming that the rate doesn't *continue* to accelerate, which it certainly will

        Over the last decade (2013-2017, the last year measured in the paper), the rate of ice loss has slowed (I'm basing this on the paper). So you shouldn't assume that as a given.

        • Re:Some Context (Score:5, Interesting)

          by Barsteward ( 969998 ) on Wednesday December 11, 2019 @03:01AM (#59506990)
          That has to be the worlds shortest decade 2013-2017

          The peak year for ice loss, according to the observations, was 2011 when 335bn tonnes of ice were lost. Since then, the average rate has slowed to 238bn tonnes a year from 2013, but this does not include the most recent observations from this summer, which showed even more widespread melting.
          it may have slowed but its still up from 3.8b tonnes in the 1990s to 238bn tonnes per year in the past decade
        • Comment removed based on user account deletion
      • Re:Some Context (Score:4, Insightful)

        by Ol Olsoc ( 1175323 ) on Wednesday December 11, 2019 @08:17AM (#59507420)

        Not to mention, some people would like the human race to endure longer than just one more century.

        Sigh. AGW is hardly likely to cause our extinction. What it will do is cause a lot of instability as some places that are productive now change their weather. Some areas might become desertified, some areas that are marginal for producing crops might find themselves the new "bread basket" of the world. some areas might end up with monsoon type weather patterns. After all, the effects overall will be more precipitation.

        This can give rise to destabilizing climate change refugees, as people in once productive areas move to find new areas to settle in.

        So not likely to cause extinction, but very possible that some of the powers that be at present will be rather marginalized by the changes.

      • "That's assuming that the rate doesn't *continue* to accelerate"

        So many possible replies to this, from the flippant: this morning it was 40 degrees outside, an hour later it was 45, an hour after that it was 51. If that 'warming' continues to accelerate, by my math tomorrow morning it'll be 400 degrees outside! ...to the serious: please look at https://en.wikipedia.org/wiki/... [wikipedia.org]
        This is a non-disputed concatenation of historical temperatures derived from various proxies - dendrochronology, ice cores, etc. No

    • You're math is not accounting for acceleration of melting. In other words if the rate of acceleration is 7x per 30 years, we can expect 2400x melting rate by 2100 compared to 1990. Can we agree we're all jellyfish-food at that point?
      • But real world systems rarely experience that sort of exponential growth. When's the last time you left a plant growing and it spread through the whole neighborhood? Natural systems have complicated natural feedback systems that limit growth.

    • More context. SuperKendall thinks that 2 point linear extrapolation for a model that is changing a lot in a short time is somehow valid over a century.

      Based on the my projections using the same model applied to Super Kendall's last two posts, 3 posts from now he will have a negative IQ.

    • But a great source of water to ship to the Sahara!

    • by gtall ( 79522 )

      Along the same lines as that story, the Arctic is now a net contributor to carbon emissions. This is what really scares climate scientists and others, it indicates a runaway greenhouse effect. So your denialism is probably okay for a few years, then it won't be.

  • I will have seaside property very soon, as all the ice keeps melting. As for all those pore bastards at lower elevations than me, they should have planned ahead! If you cant tell I'm kidding, we are in fact all screwed with global warming. The waters will rise, and the landmass area above the water line will shrink to levels that can no longer hold or feed the current population.
    • As for all those pore bastards at lower elevations than me, they should have planned ahead!

      All those people who have elevation 67cm lower than you?

      • by gl4ss ( 559668 )

        well yea. actually it's not like that at all as long as you would be somewhere near seaside on a hill you can have lots of leeway in regards of the water rising and still maintaining seaside property.

        really the rising water worst case scenarios are really not that bad - missippi area is largely fked of course - it's the other possible weather effects from it that could be bad.

        globally looking at a map level even rising the water 30 meters is really not so bad. 67 centimeters affects most places very little

        • by HiThere ( 15173 )

          Yeah, but be aware that the map is deceptive. Canada is a lot smaller than it looks on the map, because of distortion as a sphere is projected onto a plane.

          • by gl4ss ( 559668 )

            well the whole starting value for that particular map is deceptive as f. siberia and canada are still big af though. the interesting thing would be to model what would happen with rainfall patterns in regards of sahara if parts of it got submerged. thats a large swath of land that we can't farm now.

            anyhow if there's one thing thats pissing me off about the global warming/water rising alarmist folk is that .. very few of them seem to be making models and/or preparing for it. just saying that it's going t

            • what if instead we actually started making some plans for if water rises 30 meters ?

              It's not going to rise 30 meters. It's going to rise 67 centimeters (according to the summary).

            • it ain't going to happen overnight, its gradual and too slow to see the changes (apart from the extreme weather patterns happening now) - a bit like evolution deniers who expect to see a creature evolve overnight otherwise evolution is false
        • venice was never meant to be a permament large city too. it's fked but it was always fked. it's just a temporary refuge from the hordes.

          As they say, Venice has been dying for 800 years.

  • by Anonymous Coward on Tuesday December 10, 2019 @11:18PM (#59506714)

    Science used to have a role in society.

    There used to be entire branches of our government directly meeting with major scientist groups - not to investigate and punish them for their actions - but to walk through the results of meta-analysis and basic scientific literacy topics on major issues of the day.

    Presidential and congressional advisory panels, places were anything not backed by actual science would be pushed away in favor of repeatable evidence and scientifically backed methods.

    They certainly weren't perfect - but since the 1990's even what little we had have been systematically eliminated.

    More than anything else, what we're really having is an erosion of basic objective reality, in favor of political realities.

    Even basic rational skeptical groups have shrunk back in popular culture - basically gone even on Youtube.

    So yeah - a little thing like the fundamental makeup of our large-scale climate systems changing on an accelerating basis is kind of going under the radar.

    To be fair - this is mostly the power of the Baby Boomers. News serves both their interests, and more importantly their lack of interests more than anything else. There's no malice - but a huge percentage of living humans have just given up caring about the concerns of the living - and kind of retreated into a cocoon of facebook and Fox news.

    Humanity waking up from that is going to be a very strange thing. Such a strange waste of time we have to live with in the meantime.

    • Science used to have a role in society.

      It still does, but it's not going to require some international science board to solve this problem. This is a local problem.

      These cities and settlements along the shores know that storms can come, and with it flood waters. These cities plan engineering projects decades in advance with plenty of margin for error to manage the flooding that comes with the storms. Smaller settlements along the sea may simply have to move to higher ground if they don't have the capacity to build seawalls and such.

      All we are

      • the consequences are "local" but the problem is global and its not just coastal places that are subject to increased flooding due to bad weather
      • by MrKaos ( 858439 )

        may simply have to move to higher ground if they don't have the capacity to build seawalls and such.

        Like Fukushima. Gee I wish they built a seawall.

  • by magzteel ( 5013587 ) on Wednesday December 11, 2019 @12:07AM (#59506792)

    Conclusions from the actual report. Thank goodness The Guardian writers are experts at reducing complex, nuanced information into a scary headline.

    Conclusions

    We combine 26 satellite estimates of ice sheet mass balance and assess 10 models of ice sheet surface mass balance and 6 models of glacial isostatic adjustment, to show that the Greenland Ice Sheet lost 3800 ± 339Gt of ice between 1992 and 2018. During the common period 2005 to 2015, the spread of mass balance estimates derived from satellite altimetry, gravimetry, and the input-output method is 24 Gt/yr, or 10% of the estimated rate of imbalance. The rate of ice loss has generally increased over time, rising from 18 ± 28 Gt/yr between 1992 to 1997, peaking at 270 ± 27 Gt/yr between 2007 and 2012, and reducing to 239 ± 20 Gt/yr between 2012 and 2017. Just over half (1971 ± 555 Gt, or 52%) of the ice losses are due to reduced surface mass balance (mostly meltwater runoff) associated with changing atmospheric conditions [13,14], and these changes have also driven the shorter-term temporal variability in ice sheet mass balance. Despite variations in the imbalance of individual glaciers [4,5,33], ice losses due to increasing discharge from the ice sheet as a whole have risen steadily from 41 ± 37 Gt/yr in the 1990’s to 87 ± 25 Gt/yr since then, and account for just under half of all losses (48%) over the survey period.

    Our assessment shows that estimates of Greenland Ice Sheet mass balance derived from satellite altimetry, gravimetry, and the input output method agree to within 20 Gt/yr, that model estimates of surface mass balance agree to within 40 Gt/yr, and that model estimates of glacial isostatic adjustment agree to within 20 Gt/yr. These differences represent a small fraction (13%) of the Greenland Ice Sheet
    mass imbalance and are comparable to its estimated uncertainty (13 Gt/yr). Nevertheless, there is still departure among models of
    glacial isostatic adjustment in northern Greenland. Spatial resolution is a key factor in the degree to which models of surface mass balance
    can represent ablation and precipitation at local scales, and estimates of ice sheet mass balance determined from satellite altimetry and the
    input-output method continue to be positively and negatively biased, respectively, compared to those based on satellite gravimetry (albeit
    by small amounts). More satellite estimates of ice sheet mass balance at the start (1990’s) and end (2010’s) of our record would help to reduce
    the dependence on fewer data during those periods; although new missions [49,50] will no doubt address the latter, further analysis of historical
    satellite data is required to address the former.

  • https://en.wikipedia.org/wiki/... [wikipedia.org]

    Bye all.............

  • Shouldn't we have negative 5 million farms in the US by now?
  • Greenland has lost 3.8 trillion tons of ice since 1992

    This number means absolutely nothing to the layman. I'd like to know what percentage of Greenland ice does it constitute - 1%, 0.1%, 0.0001%? It is like saying that a tree produces 2 cubic meters of oxygen without specifying the time period.

  • by phoenix321 ( 734987 ) on Wednesday December 11, 2019 @09:52AM (#59507746)

    With a basic understanding of exponentials, one could immediately spot the panic narrative the press is producing here. No development can double, quadruple, septuple its growth rate that often.

    If someone had invested 1 (one) dollar around Jesus birthday at 1% interest rate, it would have increased to about 525 million dollars by now. For a 5% interest rate, it would be around 4,089,596,209,829,250,000,000,000,000,000,000,000,000,000.00 Dollars by now, give or take a few billion in the digits that my current calculator cannot display.

    That is a 1% or 5% increase of something per year over 2000 years. Despite these immense numbers, it's a *constant* growth rate. An accelerating growth rate, no matter how slowly it'd be accelerating, would break the limits of any system within a few iterations, no matter how large the system was.

    To understand the effect of an "accelerating growth rate", even if the increase in yearly growth is absolutely minuscule, the same example: 1 dollar invested in the year 1 CE, at 1% interest rate, with the interest rate itself rising by a measly 1% per year, so 1% interest in the first year, 1,01% in the second year, 1,0201% in the third and so forth. Not "doubling" or "septupling" the growth rate as the press claims the warming or ice loss is, but a meager 1% growth rate INCREASE per year. So for 1 dollar invested into such a scheme at year 1 CE, the accumulated capital would be off the charts and outside of excel after year 796, leaving the charts at 2,97*10^307, a few quadrillion dollars per atom in the observable universe, give or take.

    So nothing in the world can sustain an accelerating growth rate. Ever. Anyone who claims an accelerating growth rate for anything will be proven right or a liar within a few cycles of their predictions. NOTHING at all can ever double their growth rate regularly. Not bacterial colonies under ideal conditions, not nuclear fission events and not nuclear fusion either and not the expansion of the universe, either. Anyone who claims doubling growth rates of anything is lying.

    If "ice loss rate" really was septupling over a few years, there wouldn't be any ice left in the entirety of the solar system by next month.

    • With a basic understanding of exponentials, one could immediately spot the panic narrative the press is producing here. No development can double, quadruple, septuple its growth rate that often.

      A landslide can, for a short period. Nobody is claiming it can go on forever. The claim is that it can go on long enough to fuck us up good.

      If someone had invested 1 (one) dollar around Jesus birthday at 1% interest rate, it would

      ...be irrelevant to a discussion on climate change.

      nothing in the world can sustain an accelerating growth rate. Ever.

      Right, there's a limit. And that limit is when all the ice melts, and the sea level rises enough to make feeding the population improbable.

The unfacts, did we have them, are too imprecisely few to warrant our certitude.

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