Clear Signs That Part of the Greenland Ice Sheet Is Close to a Tipping Point

Accelerated Melt Greenland Ice Sheet

Accelerated melt. Credit: TiPES/HP

An analysis of the melt situation on the Central-Western Greenland ice sheet reveals clear signs of tipping.

Data from the Jakobshavn drainage basin of the Central-Western Greenland ice sheet reveals the distinct mark of this part of the ice sheet having reached a tipping point. That is the conclusion by Niklas Boers from Potsdam Institute for Climate Impact Research, Germany and Martin Rypdal from the Arctic University of Norway, after careful studies of the development in melt rates and ice-sheet height changes during the last 140 years. The two authors propose close monitoring of the Greenland ice sheet to assess the situation. The work, published in PNAS today, is part of the TiPES project, coordinated and led by the University of Copenhagen, Denmark, and the Potsdam Institute for Climate Impact Research, Germany.

In the article, Rypdal and Boers have analyzed reconstructions of the height changes of the Central-Western Greenland ice sheet since 1880, and have compared them to corresponding model simulations. From the analysis, they conclude that this part of the Greenland ice sheet is losing stability, consistent with the idea that it is very close to tipping into a state of accelerated melting, regardless of whether the arctic warming trend is halted in the coming decades.

„We might be seeing the beginning of a large-scale destabilization, but at the moment we cannot tell, unfortunately. So far, the signals we see are only regional, but that might simply be due to the scarcity of accurate and long-term data for other parts of the ice sheet,” says Dr. Niklas Boers.

An ice sheet can only maintain its size if the loss of mass from melting and calving glaciers is replaced by snow falling on to its surface. The warming of the Arctic disturbs this mass balance because the snow at the surface often melts away in the warmer summers.

Melting will mostly increase at the lower altitudes, but overall, the ice sheet will shrink from a mass imbalance. Therefore, a positive feedback mechanism kicks in: as the ice sheet surface lowers, its surface is exposed to higher average temperatures, leading to more melting, further height reductions, and correspondingly accelerated mass loss. Beyond a critical threshold, this process can not be reversed, because with reduced height a much colder climate would be needed for the ice sheet to regain its original size.

The instability that Boers and Rypdal have found in melt and reconstructed ice-sheet height data from the Central-Western Greenland ice sheet indicates that the critical threshold has at least regionally been reached due to the last 100 years of accelerated melting.

The increase in surface melt will possibly be compensated at least partly by increases in snowfall as precipitation patterns over the ice sheet will change due to the changing ice-sheet height.

However, if the Greenland ice sheet as a whole transits into accelerated melting there will be severe consequences for the entire planet. The Greenland ice sheet contains the mass equivalent to raising global sea level by 7 meters. A loss of the Greenland ice sheet is also expected to add to global warming due to decreasing albedo as well as disrupt major ocean currents, monsoon belts, rainforests, wind systems and precipitation patterns.

“We need to monitor also the other parts of the Greenland ice sheet more closely, and we urgently need to better understand how different positive and negative feedbacks might balance each other, to get a better idea of the future evolution of the ice sheet,” says Niklas Boers, who together with Martin Rypdal expects to see accelerated melting in the near future.

Reference: “Critical slowing down suggests that the western Greenland Ice Sheet is close to a tipping point” by Niklas Boers and Martin Rypdal, 17 May 2021, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2024192118

The TiPES project is an EU Horizon 2020 European interdisciplinary climate science project on tipping points in the Earth system.

12 Comments on "Clear Signs That Part of the Greenland Ice Sheet Is Close to a Tipping Point"

  1. More scary projections/models. Wealthy US Democratic politicians are still happy to buy beachfront property.

  2. O’Connell David | May 17, 2021 at 8:13 pm | Reply

    The latest cry of impending doom! Check back with me in the “near future” and let me know when it tips 🙄

  3. Todd Mondragon | May 18, 2021 at 12:09 am | Reply

    Amazing how science deniers come to science sites to spread their ignorance in the comments sections.

  4. the tipping point was over 50 years ago…lol.

  5. Brad Martin | May 18, 2021 at 2:24 am | Reply

    I’ve owned waterfront property for 24 years. The lowest low tides are 5 inches higher now than they were in 1998. Sea level rise is real. Slow, but real.

    • JOSEPH J CAREY | May 18, 2021 at 5:58 am | Reply

      hmmm did you know that the ground you and your house is on is moving? it a scary thing called plate techtonics eventualy (in millions of years) the ground your standing on will be 100s of feet under water!!! oh no if i were you i would sell now.

  6. The “tipping point”… It’s an old steel-makers’ term for the point where the crucible dumped its molten contents. Steel yourselves: the point of no return occurred 30+ years ago. It’s been gaining ever since. Twenty years ago the rate accelerated (became wholly logarithmic/exponential as opposed to arithmetic) and difficult to deny. Nature’s a fickle Lady, but no LADY at ALL, when ignored. By the time her “displeasure” becomes manifest, your neck (and other body parts) are already on the block. “OFF WITH YOUR HEAD(S)…” We were warned.

    SO MUCH FOR GENDER-BASED/BIASED ANALOGIES. Nature is a mechanism (The GAIA PRINCIPLE ASIDE). Pure PHYSICS (and maybe POETRY) in motion. There is no “Mother-person” to which one might appeal, or tender/render an apology. You might as well go ahead and jump… in front of a moving train. Barring an outright MIRACLE: Even if the Cosmic Engineer puts the brakes on, the forces of Nature (like a train) would leave one in its wake, a grease spot on the rails. Those rails were laid in the Late 19th Century, when ANTITHETICAL Capital and Industry thumbed their noses at NATURE’S THESIS. The SYN-THESIS is what we are seeing/living today. Ah! The DIALECTIC of the MEAN. It is LOGICAL, Philosophically sound but terminally flawed: Jump off a cliff without a parachute, para-sail, or similar invention, and argue the point on the way down. Nature’s closing rebuttal will end all debate.

    THERE’S STILL TIME, BROTHER! The closing “Sign of the Times” in the 1959 Movie: ON THE BEACH; starring Eva Gardner (among others) at her acting best. Worth a watch if you dare.

    Meanwhile, back on a cliff nearby the beach… Nice day for a SWIM. I’m jumping in…

    Where there is WATER there is LIFE…

  7. The sad reality is that it will take a major event such as damaging sea level rise to convince the majority of people that global climate change is real. Even when their favorite beach in underwater, some of them will still be in denial.

  8. Clyde Spencer | May 18, 2021 at 8:25 am | Reply

    The problem with research of this nature is that it leads to conclusions that are possibilities, without an assessment of the probability. The writing is peppered with words like “very close, might be seeing, might simply be due, will possibly be compensated, and, is also expected.” None of these statements give me confidence that they have more than conjectures based on subjective opinions. Everything is vague and ambiguous.

    It has been said that mathematics is the language of science. Where are the numbers? Where are the numerical uncertainties? Where are the mathematical models that express the relationships between the numerous variables? This is classical hand waving!

    No sane person runs their life based on possibilities alone (e.g. potential asteroid impacts, fatal accident today, alien invasion, etc.). Instead, we operate based on probabilities, albeit perhaps poorly understood, but they are still assessments of probability, not just a plausible mechanism to establish a possibility.

    This isn’t science! It is instead, technicians gathering data and then speculating on what it means. It is only the first step in the Scientific Method.

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