Harvard Researchers Say Antarctic Ice-Sheet Melting to Lift Sea Level 30% Higher Than Thought

Scotia Sea Ice

This was taken in the Scotia Sea during the coring campaign in 2007. Credit: Michael Weber

New calculations show the rise due to warming would be 30% above forecasts.

Global sea level rise associated with the possible collapse of the West Antarctic Ice Sheet has been significantly underestimated in previous studies, meaning sea level in a warming world will be greater than anticipated, according to a new study from Harvard researchers.

The report, published in Science Advances, features new calculations for what researchers refer to as a water expulsion mechanism. This occurs when the solid bedrock the West Antarctic Ice Sheet sits on rebounds upward as the ice melts and the total weight of the ice sheet decreases. The bedrock sits below sea level so when it lifts, it pushes water from the surrounding area into the ocean, adding to global sea level rise.

The new predictions show that in the case of a total collapse of the ice sheet, global sea level rise estimates would be amplified by an additional meter within 1,000 years.

“The magnitude of the effect shocked us,” said Linda Pan, a Ph.D. in earth and planetary science in GSAS who co-led the study with fellow graduate student Evelyn Powell. “Previous studies that had considered the mechanism dismissed it as inconsequential.”

“If the West Antarctic Ice Sheet collapsed, the most widely cited estimate of the resulting global mean sea level rise that would result is 3.2 meters,” said Powell. “What we’ve shown is that the water expulsion mechanism will add an additional meter, or 30 percent, to the total.”

But this is not just a story about the impact that will be felt in hundreds of years. One of the simulations Pan and Powell performed indicated that by the end of this century global sea level rise caused by melting of the West Antarctic Ice Sheet would increase 20 percent by the water expulsion mechanism.

“Every published projection of sea level rise due to melting of the West Antarctic ice sheet that has been based on climate modeling, whether the projection extends to the end of this century or longer into the future, is going to have to be revised upward because of their work,” said Jerry X. Mitrovica, the Frank B. Baird Jr. Professor of Science in the Department of Earth and Planetary Sciences and a senior author on the paper. “Every single one.”

Pan and Powell, both researchers in Mitrovica’s lab, started this research while working on another sea level change project but switched to this one when they noticed more water expulsion from the West Antarctic ice sheet than they were expecting.

The researchers wanted to investigate how the expulsion mechanism affected sea level change when the low viscosity, or the easy-flowing material of the Earth’s mantle beneath West Antarctica, is considered. When they incorporated this low viscosity into their calculations they realized water expulsion occurred much faster than previous models had predicted.

“No matter what scenario we used for the collapse of the West Antarctic Ice Sheet, we always found that this extra one meter of global sea level rise took place,” Pan said.

The researchers hope their calculations show that, in order to accurately estimate global sea level rise associated with melting ice sheets, scientists need to incorporate both the water expulsion effect and the mantle’s low viscosity beneath Antarctica.

“Sea level rise doesn’t stop when the ice stops melting,” Pan said. “The damage we are doing to our coastlines will continue for centuries.”

Reference: “Rapid postglacial rebound amplifies global sea level rise following West Antarctic Ice Sheet collapse” by Linda Pang, Evelyn M. Powell, Konstantin Latychev, Jerry X. Mitrovica, Jessica R. Creveling, Natalya Gomez, Mark J. Hoggard and Peter U. Clark, 30 April 2021, Science Advances.
DOI: 10.1126/sciadv.abf7787

7 Comments on "Harvard Researchers Say Antarctic Ice-Sheet Melting to Lift Sea Level 30% Higher Than Thought"

  1. “The new predictions show that in the case of a total collapse of the ice sheet, global sea level rise estimates would be amplified by an additional meter within 1,000 years.”

    Doesn’t seem like a lot during a 1000 years

    “If the West Antarctic Ice Sheet collapsed, the most widely cited estimate of the resulting global mean sea level rise that would result is 3.2 meters,” said Powell. “What we’ve shown is that the water expulsion mechanism will add an additional meter, or 30 percent, to the total.”

    Are this numbers also over 1000 years?

    “One of the simulations Pan and Powell performed indicated that by the end of this century global sea level rise caused by melting of the West Antarctic Ice Sheet would increase 20 percent by the water expulsion mechanism”

    “one of the simulations” LMAO, I can make a trillion simulations where a bet in some high prize game, it’s guaranteed that, despite the odds, I will win a lot of money in some simulation runs.

    Again it’s impossible to gain any practical knowledge with this articles/studies (not really sure where is the issue, probably in both) because there is no mention of probabilities, are the simulations worst case scenario, in what timeline this “total collapse” might happen?…

    The only thing this articles are achieving is alarming and manipulating “innocent” people and confirming to “redpilled individuals” that there is an organized effort to push this propaganda.
    I’m not denying there is no reason for concern, but there is no reason for this level of concern according to what I’ve read and observed over the years.

    One theory for the push of this alarmist propaganda is that if they were honest with the message they pass no one would care about “climate change”, while it might pose a moderate threat over a certain timeline, specially in some regions, and governments are acting on the basis of prevention of worst case scenarios, after all, the burden will be mostly on peoples behavior, lifestyle and quality of life and this “need for change” will increase the rate of progress and innovation, being a major drive for total control of the population through international cooperation and strong government control over the citizens actions.
    I believe that this is probably the most likely scenario here, if you take a critical look at the Agenda for the 21st century and 2030 you can see where they are going with this, total control it is then, no way to stop the machine. The next 10 years will be hard, but you know, hard times create strong people.

    • Clyde Spencer | April 30, 2021 at 2:26 pm | Reply

      “Doesn’t seem like a lot during a 1000 years”

      “One silly little millimeter” per year, to paraphrase an old advertising slogan.

      Who knows what the climate will be like in a thousand years, or if humans will even still be around.

    • I agree. We are spending all this money and time to discover that water levels will rise a meter over a thousand years. Highly doubtful that humanity as we know it today will even care about such a thing, is foolish. Our technology will have advanced so much in this time that it’s ridiculous to even consider this to be a worry. I’m all for saving our planet, especially all the fauna/Laura living on it, but let’s be honest, if we haven’t found a solution to our pollution levels by then, none of it will even matter

  2. Clyde Spencer | April 30, 2021 at 2:20 pm | Reply

    It is appropriate to take into account the local isostatic adjustments resulting from removing the ice-load on land. However, to be thorough, one should also factor in the isostatic adjustments (with an opposite sign) to the ocean basins, resulting from the increased weight of water derived from that melting.

    Also, speaking of being thorough, it should be abundantly clear that if the western Antarctic ice sheet is responding differently than eastern Antarctica (Which it is!) then it probably isn’t anthropogenic CO2, causing the entire atmosphere to warm, that is responsible. It is more likely to be anomalous geothermal heat associated with the 90-some sub-surface volcanoes recently identified in the western region. It is probably an extension of the notorious Pacific Ring of Fire.

    In case it isn’t obvious, if the more rapid melting in west Antarctica is the result of volcanic activity, there is nothing that humans can do about it!

  3. Fidel Chavez | May 2, 2021 at 7:57 am | Reply

    Need out freezers up there or something making sound like godzilla meltdown

  4. Fidel Chavez | May 2, 2021 at 8:01 am | Reply

    The sun rays is to hot at the north pole and south pole we need put protectection on outer
    space

  5. As global warming is tied to the atmosphere, I used my long unused math skills to figure out the volume of the 3.22km shell of breathable air around our planet. To do this I added 3.22 km to the Earth’s radius, and found that volume, and subtracted the volume of the Earth itself. This left the volume of the “shell” to be 1639759676.949 cu. km., or .00152% of the volume of the Earth itself. Perhaps, when we visualize the affect of the human species on our planet, we should think of the thin skin that surrounds us, and not the area of the whole planet.
    Everything that causes heat, and that causes heat to be trapped, exists in this thin shell, which can be seen hugging the earth in pictures showing the arc of our planet. Thinking about all human activities occurring in this eggshell of space can make one feel a lot different about the planet’s reaction to our being here. In fact, the mathematics causes me to become even more a “climate denier denier” as anyone who would think that we have had no effect on this planet should realize that the .00152% is a very small space in which to house 7.152 billion people, and all the activities which they are responsible for.

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