Antarctic ice sheet could suffer a one-two climate punch

From EurekAlert!

Public Release: 14-Jan-2019

Antarctic ice sheet could suffer a one-two climate punch

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Roughly 15 million years ago, when Earth’s atmosphere was supercharged with carbon dioxide, oceans warmed and sea ice around Antarctica disappeared, causing a significant part of the Antarctic ice cap to melt and dramatically elevate global sea levels (left). New research warns that a warming world caused by increased carbon dioxide in the atmosphere and coupled with periodic changes in the geometry of Earth’s orbit could warm oceans, leading to a loss of sea ice (right) and sparking a dramatic retreat of the Antarctic Ice Sheet, and elevate sea levels worldwide. Credit Richard Levy

University of Wisconsin-Madison

MADISON, Wis. — Scientists have long speculated that our planet’s climate system is intimately linked to the Earth’s celestial motions.

The pacing of the most recent ice ages, for example, is attributable to changes in the shape of our planet’s orbit around the sun as well as to cyclic changes in the tilt of the Earth on its axis and its “top-like” wobble on that axis, all of which combine to influence the distribution and intensity of solar radiation.

Now, it turns out that variations in the axial tilt — what scientists call “obliquity” — of the planet have significant implications for the rise and fall of the Antarctic Ice Sheet, the miles-deep blanket of ice that locks up huge volumes of water that, if melted, would dramatically elevate sea level and alter the world’s coastlines.

Writing this week (Jan. 14, 2019) in the journal Nature Geoscience, a team led by Richard Levy of New Zealand’s GNS Science and Victoria University of Wellington, and Stephen Meyers of the University of Wisconsin-Madison describes research that matches the geologic record of Antarctica’s ice with the periodic astronomical motions of the Earth. Comparing the two records, the New Zealand and Wisconsin researchers recapitulate the history of the Antarctic Ice Sheet throughout most of the past 34 million years, starting when the ice sheet first formed.

Underpinning the new perspective of the Antarctic Ice Sheet is a refined assessment of the sensitivity of the Earth’s climate system to changes in obliquity, a powerful tool for probing the icy history of Antarctica.

The research is important because it teases out the pattern of growth and decay of the ice sheet over geologic time, including the presence of sea ice, a thin and fragile layer of frozen ocean surrounding Antarctica. A critical finding suggests that in a world warmed by a growing amount of atmospheric carbon dioxide, a loss of sea ice would likely amplify the cyclic effects of the Earth’s obliquity on the ice sheet as ocean waters warm. A loss of sea ice due to warming climate could trigger instability of the Antarctic Ice Sheet with dire implications for global sea levels.

“What this study does is characterize the growth and decay of the Antarctic Ice Sheet and sheds light on what is forcing it to change,” explains Meyers, a UW-Madison professor of geoscience and an expert on how climate responds to changes in solar radiation from Earth’s astronomical motions. “What has become apparent through this work and other studies is that the Antarctic Ice Sheet isn’t just sitting there. It is vulnerable to decay.”

First measured in the late 1950s by UW-Madison glaciologist Charles Bentley, the West Antarctic Ice Sheet alone contains enough ice to raise sea level by roughly 5 meters. The continental ice sheet is, by far, the largest single mass of ice on Earth. Miles deep in places and containing more than 26 million cubic kilometers of ice. The ice sheet is so heavy, Bentley and his colleagues discovered, that much of the West Antarctic ice sheet sits on land thousands of meters below sea level, making it a marine ice sheet in places.

Marine ice sheets, note Levy and Meyers, are especially sensitive to heat delivered by ocean currents. Fast flowing inland ice streams of the West Antarctic are buttressed by floating ice shelves, which — if diminished or lost — raise the possibility of a runaway flow of West Antarctica’s marine ice.

The new research suggests that a reduction in sea ice due to climate change would erode the barrier keeping the ice sheet — including the parts of it below sea level — in place.

“Sea ice creates a barrier between the ocean and the ice. If we fail to achieve carbon dioxide emissions targets and Earth’s average temperature warms more than 2 degrees Celsius, sea ice will diminish and we jump into a world that is more similar to that last experienced during the early to mid-Miocene,” says Levy, referencing a geological epoch that ended about 14 million years ago when the Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius (7 to 9 degrees Fahrenheit).

To recreate the history of the ice sheet, Meyers and Levy turned to the geologic records surrounding Antarctica and linked them to more distant deep-sea marine sediment cores containing the fossil shells of ocean dwelling microscopic organisms known as foraminifera, or forams. The chemistry of foram shells, oxygen isotopes in particular, contains a signature that documents the ebb and flow of Antarctic ice, Meyers explains. Forams living in the deep ocean accumulate isotopes in their shells, and different isotopes of oxygen can yield a detailed chemical record of the changing volumes of the Antarctic Ice Sheet.

These geological records, say Levy and Meyers, suggest significant variability in the size of the Antarctic Ice Sheet driven by the predictable changes in Earth’s astronomical parameters and threshold changes in atmospheric carbon dioxide levels. Prior to this new research, why the ice sheet responded differently to the same astronomical cycles at different times was a puzzle. Linking those cycles to a detailed chemical record suggests that elevated carbon dioxide in the atmosphere and the resulting loss of sea ice around the Antarctic played a big role in amplifying the effects of changes in the Earth’s astronomical motions on the durability and stability of the Antarctic Ice Sheet.

“All of these data suggest we need to get cracking and reduce our greenhouse gas emissions,” says Levy, noting that 2017 and 2018 saw reduced Antarctic sea ice after several decades of growth. “We don’t want to lose that sea ice.”

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This study was supported by the New Zealand Ministry of Business, Innovation and Employment contract C05X1001 (R.H.L., T.R.N., N.R.G. and R.M.M.) and by National Science Foundation grant EAR-1151438 (S.R.M.).

 

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111 thoughts on “Antarctic ice sheet could suffer a one-two climate punch

  1. If the temperature increases by 2C, then isn’t the temperature still below freezing? If so how can the ice melt? Just asking

    • It would take just a little warming of the water surrounding Antarctica, to effect large changes in the ice. The water around the glaciers is currently very close to the freezing point of sea water. A few fractions of a degree would increase melt, and glacial surge.

      • Due to the mass differences of air and water, wouldn’t a 2C increase in the air result in a hardly measurable amount on increase in the water?

        • 2C warming with accompanying increase in humidity in a -50C environment is highlikely to result in more snowing on the continent, thereby reducing water in the ocean. Look, the ice sheet itself is “miles thick”, Even a mountain in California this high accummulates snow and ice. I admonish readers here to think critically and logically always (that the researchers themselves don’tdo so, is even more apalling). It isn’t a political argument or one that you appeal to feelings to assess. Also, if you are truly convinced of the warming to disaster case, it is not only okay to disagree with a given article that supports you’re theory, it reinforces that you have made your determination thoughtfully. Don’t be convinced by Hillaty Clinton or Donald Trump on climate theory!

          Also these guys and gals are geologists and should be aware that plate tectonics (Continental Drift) shifted the continents after the the Jurrassic and is still going on. This placed the continental masses at their present locations vis a vis the poles with present ocean currents ideal for the formation of the ice sheets that accumulated 18million ya. You can’t reverse this process back to the pre-existing states with a couple of degrees C. That is with 99.999….% certainty! Moreover, riddle me this? Were the celestial motions in play during former geological eras? Of course they were! Poor CO2’s magic is being called upon to do some awfully heavy lifting!

          Now, can we get geological changes that could put us in a Juraasic type world, far more different than the NZ alarmist idea. Yes by continued pkate tech, by collision with a large bolide?

          • warmer by 3 to 4 degrees Celsius … 7 to 9 degrees Fahrenheit

            I think their numbers are off
            3C increase is 5.4F abd 4C increase is 7.2F

          • Oh noes, are you saying that change is real, that it is constant, and that we have no ability to do anything about it. So global warming, glaciations, sea level rise, and mass extinctions are inevitable. I might have to change my underwear.
            Oh, I just realized that you are talking on geological time scales. Continents are moving at the speed my fingernails grow. Major cosmic impacts happen every few million years.
            Dinosaurs were around for about 180 million years but still have living relatives so add another 65 million years.
            Sea levels rise rapidly at the end of major glaciations and then level off for many millennia. When they start dropping it may be time to get out your parka as the next glaciation is likely beginning. That too will probably take thousands of years, though.
            Unless science can find a way to make me immortal I see no reason to increase my laundry allowance.
            If my descendants cannot adapt in that time they deserve to follow the dinosaurs.

          • You mean you don’t believe a 2 degree C rise won’t melt the glaciers in an area where the average daily temp is 59 degrees below zero F? What are YOU, a real scientist or something?

      • “It would take just a little warming of the water surrounding Antarctica, to effect large changes in the ice. The water around the glaciers is currently very close to the freezing point of sea water. A few fractions of a degree would increase melt, and glacial surge.”

        Large changes of sea ice already happen with summer and winter RE the di annual change of seasons. These changes in temperature dwarf any supposed change of 2C in the atmosphere. YOU DON’T KNOW WHAT IN THE HELL YOU ARE TALKING ABOUT. I am sorry but I am losing patience with this scam because carbon taxes and extra taxes on gasoline in Canada are costing us all a lot of money.

      • Ah Less, the water there could be below freezing, as it has salt in it. As to the ice melting, we would probably see a 10,000 year melt, it ain’t gonna melt over nite. As Paul says, it will still be below freezing for land ice. The goreBULLwarming is nothing butt BS

  2. According to Hank Johnson (Dolt-GA), we must redistibute the population to mitigate the tilt of the Earth on its axis.

    • We can call Hank’s new theory THE THEORY OF GLOBAL POSITIONING. It is lucky that CO2 is well mixed. The alarmists would be calling for the earth to tip over if we put too much CO2 into the atmosphere. I know this guy who believes that the earth is flat. No matter what videos I point him to on the internet, he always says that everyone of them is fake. No amount of facts will persuade him. He will go to his grave thinking the way he does. I am afraid that is the same way with alarmists. Look at the examples of Stokes and Mosher. 2 very intelligent guys who are so blinded by groupthink that they just refuse to consider any interpretation other than the decrees of Al Gore’s Church of Climatology.

  3. It has grown. It is known.

    Zhang et al., 2019
    https://www.researchgate.net/profile/Liping_Zhang19/publication/329372480_Natural_variability_of_Southern_Ocean_convection_as_a_driver_of_observed_climate_trends/links/5c0592f4a6fdcc315f9ad416/Natural-variability-of-Southern-Ocean-convection-as-a-driver-of-observed-climate-trends.pdf

    “Observed Southern Ocean surface cooling and sea-ice expansion over the past several decades are inconsistent with many historical simulations from climate models. Here we show that natural multidecadal variability involving Southern Ocean convection may have contributed strongly to the observed temperature and sea-ice trends.”

    The models are in direct opposition to the actual observations. The models are wrong. And then some.
    http://notrickszone.com/wp-content/uploads/2019/01/Southern-Ocean-cooling-and-sea-ice-growing-since-1979-Zhang-2019.jpg
    http://notrickszone.com/wp-content/uploads/2019/01/Southern-Ocean-temp-and-sea-ice-modeling-failures-Zhang-2019.jpg
    Getting not even the sign right is quite poor.

  4. All of these data suggest we need to get cracking

    Now there’s a precise, technical and scientific conclusion you don’t see very often.

    • Meanwhile the magnetic pole is trundling it’s way over to Siberia. Bit of s shift in the magma methinks.

      • The North magnetic pole intensity appears to be responsible mainly for the ~ 60 year quasi-periodic oscillation (North Atlantic Anomaly – AMO) evident in the global temperature anomaly.
        While the South pole might be responsible for the sudden rise in the recent warming period as shown here
        http://www.vukcevic.co.uk/DNS.gif
        the global temperature shows high correlation with the magnetic dipole (green line) as can be seen here:
        http://www.vukcevic.co.uk/CT4-GMF.htm
        Note that the magnetic dipole hit a pause (hiatus) during the last 25 years which has been reflected in the GT’s anomaly about a decade later.
        I could see no stronger correlation with the CO2 rise.

        • Wow, that is a very good correlation! I think the physical process behind it would be cloud generation by increased radiation from space due to the weak periods of the magnet field. It’s the same process that was suggested to explain correlation between the Sun’s magnetic field and Earth’s temperature.

          • If the north magnetic pole shifted by 30 degrees and the south magnetic pole by only 10 degrees, then the two magnetic poles would not be diametrically opposite each other on the earth. This would result in an unbalanced magnetic field, which would be stronger on the side of the earth where the two poles are closest, and weaker on the side where the two poles are farther away. Is this physically possible?

            The solar wind (charged particles emitted from the sun) tend to be deflected away from the earth by the magnetic field far from the magnetic poles, but follow the magnetic flux lines toward the magnetic poles, which cause the aurora borealis and aurora australis. If a magnetic pole migrated away from the pole of rotation of the earth into the middle latitudes, there would be an increase of ionic radiation near the magnetic pole, possibly in a heavily populated area.

          • Hi Steve
            Yes, the global field is asymmetric, strongest is in the eastern hemisphere along line Sibera, China & Australia and weakest western hemisphere i.e. North and South America, south America being particularly weak, google S. Atlantic magnetic anomaly.

  5. I still think it’s too early for me to invest in Antarctican beach-front property to open up a new tropical resort.

  6. Antarctic sea ice cover reached a record in 2014.
    Then contracted with the strong El Nino of 2015-2016.
    (Chartic Interactive Graph)
    Since then, the extent is slowly returning to normal.
    Will it get to the 2014 extent?
    Nothing to do with atmospheric concentrations of CO2.
    With continuation of weakening solar activity it can get back to “normal”.
    Which was setting records.

    • The decrease in Antarctic sea ice took place in a stepwise fashion immediately when the DMSP F17 satellite malfunctioned after years of having higher than average extents and has never looked the same since. I doubt it is coincidental.

      • I saw a similar “change” in Lake Michigan ice during the great freeze of 2013-14. The Powers That Be could not allow something as substantial as a historic total freeze over of Lake Michigan (would have been the first on their records) … so they changed how it was tabulated. I believe the lake completely froze over twice that winter. The extreme and consistent cold from Dec-Mar was epic and important.

    • I find funny when people talk about these things as “normal” and “average”.

      We have no idea in geologic time scales what these values are. And even if we did, they would need to be so heavily qualified and quantified which makes practically useless. The ice sheets are not “deciding” to be a size. They just are. They are not less, more, thick or thinner; they just are. No matter how much I want mountain range to go away; not even painting it pink will make it go away; it will just encase it a SEP field.

  7. Where is the pretty map showing the Laurentide Ice Sheet when it buried present day Manhattan, Boston, Chicago and environs in over 5,000 feet of ice?

  8. What evidence do they have that the historic CO2 levels were, as they imply, causing the warming, rather than the natural cycles – including solar orbital effects – causing warming which, in turn, led to net increasing CO2 emissions from the oceans in particular?

    • Yes, massive non-sequitur in their “study” –

      “IF we fail to achieve carbon dioxide emissions targets AND Earth’s average temperature warms more than 2 degrees Celsius”

      BIG “IF,” times TWO. Because contrary to their endless assumptions and assertions, CO2 has NEVER been empirically shown to drive temperature.

      “referencing a geological epoch that ended about 14 million years ago when the Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius (7 to 9 degrees Fahrenheit)”

      Amazing how the “CO2 drives temperature” assumption is projected on the “geologic epoch” of choice, when other such “geologic epochs” had much LOWER temperatures with much HIGHER CO2 levels than the “epoch” they mention, with this reverse correlation enduring for millions of years. Somehow that “supercharged” atmosphere couldn’t prevent a full blown glaciation about 450mya, for example, with CO2 about four times as high as in their example.

  9. It seems like only yesterday that the deep ocean waters of the Pacific were found to be still cooling over a very long run cycle. Oh that was yesterday.

  10. I am in the wrong business. Writing rubbish papers on subjects you can make up that no one can do anything about, scapegoating CO2 as mandatory requirement, is a career for life.

    PS I suggest there is another cause, that syncs to Milankovitch cycles. There are 140 volcanoes under Western Antarctica’s ice….they get a lot more excited at precession, obliquity and eccentricity maximums.

    https://www.dropbox.com/s/emc1kl4hnwrktlo/Image%20Table%203%20Magma.png?dl=0

  11. When Wisconsin, Madison and a university from New Zealand team up, this is the expected pseudoscientific result.

    The entire study fails at their assumption that O18 isotopes in foram tests reflect changes in Antarctic sea ice. But they can’t let anything stand in the way of desired conclusions.

    • Robert W Turner
      January 15, 2019 at 10:26 am

      Yes unfortunately Victoria University of Wellington is our equivalent of the UK’s CRU or Queensland Australia’s James Cook University…our very own warmist breeding ground.

  12. let’s see.. water has a heat capacity of near 4185 J/kg/K..

    we’re talking of 26 million cubic kilometers of ice at temperatures of what, -40C? -50C? – 80C? the energy required to accomplish melting this lot and raising the sea level by 5 meters is , to use an aussie term, oodles.

    (Probably a fair bit more than humans could achieve if we directed all of humanity’s efforts to the task of doing nothing but creating power and aiming at the ice this for centuries if not millennia)

  13. Since early hominids didn’t come into existence until the late Miocene/early Pliocene and thus could not have been driving the SUVs that are now causing Global Warming™, was it animal flatus that caused the Catastrophic Animal-caused Global Warming that lead to the melting of much of the earth’s glaciers?

  14. So, as the climate of 15 million years ago was so much hotter, I take that this is a “proof” that CO2 does not drive temperature?

  15. Well, well, well. (It’s a deep subject)
    “The ice sheet is so heavy, Bentley and his colleagues discovered, that much of the West Antarctic ice sheet sits on land thousands of meters below sea level”
    Thousands of meters is kilometers, some unspecified number.
    I an sure it will be news to many here that much of WAIS is kilometers below sea level.

    But wait, there’s more!
    “with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius”

    No runaway Greenhouse Effect, not even a Tipping Point. No Catastrophe, not even a little one.
    Please do not tell me that the climate scare of the century was nothing more than Hot Air.

    • No “runaway greenhouse effect” with SEVEN THOUSAND PARTS PER MILLION, yet we’re supposed to quake in our boots about four HUNDRED parts per million as if it is some kind of “tipping point.”

      Their assertions are so beyond stupid, it’s amazing that anyone paying the slightest bit of attention believes them.

    • It is a pisser when your alarmist study contradicts the existing dogma. Will they now be pilloried by the true believers?

  16. “says Levy, referencing a geological epoch that ended about 14 million years ago when the Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius”

    14 myo….CO2 levels were about the same as now

    where does he get “supercharged”??

    • Same place as DA Trotter of My Cousin Vinny fame, when talking about/hyping a piece of scientific equipment.

    • As a matter of fact the Miocene ended 5.3 million years ago, but what is nine million years more or less to a ClimateScientist™

      • tty
        January 15, 2019 at 1:45 pm

        Actually this is one thing they might have got just about right. They are referring to the mid-Miocene…this ran from about 16-12 million years ago (give or take a day or two) so their estimate of 14 MYA is not too bad.

        • Excuse me but no.

          It says “…referencing a geological epoch that ended 14 million years ago”. The Miocene is an epoch, the Middle Miocene is not.

          14 MYA by the way is correct for the time when the Antarctic became permanently High Arctic and virtually all plant life disappeared, though tundra vegetation apparently hung on a couple of million years longer on the northern tip of the Antarctic peninsula.

  17. Because water is denser than ice; wouldn’t melting that ice which is below sea level actually serve to lower sea level?

    • Taking isostatic adjustment into account when forecasting doomsday would be inconvenient and too scientific when it comes to climastrology.

    • No, but since cold ocean water is 13% denser than glacier ice all the ice up to sea-level, plus 13 % more would be required to fill out the space where the melted ice was.

      An example: if the bedrock under the ice is 1000 meters below sea-level, only the ice more than 130 meters above sea level will add to the global sea-level.

  18. Nothing of use anymore to the alarmists in the Arctic: actually becoming somewhat of an embarrassment, so a refocusing of attention to the next “canary in the coalmine” du jour: Antarctica.
    With descriptions like “because it teases out the pattern of growth and decay” where the data was likely run through a washing machine and mugged to near death to get it to conform to expectations, this “scientific paper” (used in the loosest of terms) was likely targetted towards advancing headlines over knowledge.

  19. And now they are claiming that the isostatically subsided Antarctic landmass and the ice sheet depressing it are marine, and as a marine ice sheet it is highly subjected to melting from warm marin waters. You might as well claim that Death Valley is a marine environment because it sits below sea level.

    Much of the WAIS sits over a closed basin (subglacial trench) due to subsidence, lying between the Transantarctic Mountain Range and West Antarctic Coastal Range and is actually more stable than if it were simply on a ramp. The fact that they think ocean currents, which are physically separated by hundreds of miles from the parts of the ice sheet below sea level, can directly melt that ice is beyond stupid.

    Furthermore, floating ice shelves do little to “buttress” the billions of tons of ice flowing down hill from the heads of the ice sheet as they claim. It’s the grounded ice flow that slows ice sheet flow.

    • “is actually more stable than if it were simply on a ramp”

      Not necessarily. Under certain circumstances such an ice mass would really be unstable. The requirements are:

      1. Sea depth at the glacier front is >90% of the ice thickness
      2. The bottom slopes monotonically downwards up-glacier
      3. This bottom slope is steeper than the glacier slope
      4. There are no thresholds or pinning points

      If this applies the glacier could at least theoretically calve out completely. Not fast, mind you, ice is quite stiff and does not flow quickly, but perhaps over a few thousand years.

      Incidentally the only way a deep ocean trough like the West Antarctic Rift Valley can ever be completely filled by ice is probably when there are shallow sills all around, or almost all around. The trough is originally covered by shelf-ice from surrounding highland glaciers. When this becomes thick enough it “grounds” on the sills and the continuing ice-flow from the highland glaciers can no longer calve into the sea but instead thickens up until it completely fills the rift.

  20. University of Wisconsin Madison’s most memorable and legitimate research with any significant data having a consequence is derived at the lake side Ratskeller, where the deepest cognitive skills prevail. Example: “uh..Like….can I …uh…get …uh …your phone number?” followed by a healthy but elongated belch. I’m an expert.

  21. We’ve had hysteria all over our broadcast tv media today about Antarctica melting in the next two weeks or something here, but based on something flammed up by the University of Utrecht. Clearly this is the next instalment of the warmest narrative – doubtless safer than merely predicting something easily falsifiable and within observable reach of most of the planet’s population. Why did it take them so long to realise this was a better way to go than hide and seek warmth in the oceans, no more snow, Asian port cities under water by year 2000, vanished Arctic ice and all the epic fails they have confidently foisted on an increasingly disbelieving public.

    • Maybe we should provide free vacations even in the Antarctic summer time to the middle of Antarctica to all the alarmists , to let them enjoy the warmth that CO2 is providing.

    • Nature Geoscience is a serious journal. It’s not Nature Climate Change.
      The paper should be taken seriously.

      • Not serious enough for proofreading though, since nobody seems to have noticed that “10^5 kyr” means 100,000,000 years, not 100,000.

  22. Obliquity is decreasing and will continue to do so for the next 10K yrs. Climate will become colder before it becomes warmer.

  23. “The pacing of the most recent ice ages, for example, is attributable to changes in the shape of our planet’s orbit around the sun as well as to cyclic changes in the tilt of the Earth on its axis and its “top-like” wobble on that axis, all of which combine to influence the distribution and intensity of solar radiation. Now, it turns out that variations in the axial tilt — what scientists call “obliquity” — of the planet have significant implications for the rise and fall of the Antarctic Ice Sheet”

    Maybe I missed it, but where did they explain the mechinism how obliquity is able to affect the AIS? Or did they just discover Milankovitch Cycles? If so, why did they mention CO2 having anything to do with the immeadicy of curtailing our meagre present CO2 emmisions? What is it…CO2 causing ice ages and melting, or long term results of Obliquity within the Milankovitch Cycles? My bet is on obliquity having first order magnitude effect in driving the remaining cycles for amplification and timing for second order affect.

    • What they try to imply is that if it gets just a leetle warmer then the Milankovich variation will melt the Antarctic Ice Sheet in short order.

  24. From the abstract:

    Our analysis reveals distinct phases of ice-sheet evolution and suggests the sensitivity to obliquity forcing increases when ice-sheet margins extend into marine environments. We propose that this occurs because obliquity-driven changes in the meridional temperature gradient affect the position and strength of the circum-Antarctic easterly flow and enhance (or reduce) ocean heat transport across the Antarctic continental margin.

    https://www.nature.com/articles/s41561-018-0284-4

    Right there the two things I have always insisted are the most important for climate: Obliquity and the temperature gradient between the Equator and Poles. It appears some scientists are starting to realize.

  25. Now, it turns out that variations in the axial tilt — what scientists call “obliquity” — of the planet have significant implications for the rise and fall of the Antarctic Ice Sheet
    Yes indeed, the obliquity is diminishing, meaning less light at the poles, but they would never mention that.

  26. Well, now I have actually read the paper. And what does it amount to? They have made a fairly strong case that the ice volume varies more strongly with the 41 000 year obliquity cycle when the ice volume is smaller, like during the Miocene Climatic Optimum, which seems reasonable. And that is about all.

    The connection to, and data on, sea-ice is weak, to put it mildly, and their correlation of cores that consist mostly of hiatuses “at 10^5 kyr resolution” is laughable. By the way, the peer review must have been even sloppier than usual for Nature not to notice that “10^5 kyr” means 100,000,000, not 100,000 years.
    Incidentally the decrease in glaciation during the MCO was probably due to partial tectonic blockage of the Drake Passage which increased heat flow to Antarctica.

    And of course there is the usual number of idiotic errors in the press release.

    “The ice sheet is so heavy, Bentley and his colleagues discovered, that much of the West Antarctic ice sheet sits on land thousands of meters below sea level”
    Hardly a new discovery and also wrong. The West Antarctic Ice Sheet is sitting on top of a deep Rift Valley, that’s why. Elementary arithmetics would have shown them that the ice-sheet isn’t nearly heavy enough.

    “the West Antarctic Ice Sheet alone contains enough ice to raise sea level by roughly 5 meters.”
    However it wouldn’t, exactly because it is situated on top of that deep Rift Valley. Most of the water would be needed to fill out the hole left by the melted ice. Even a total collapse of the WAIS would only raise the sea level about 3 meters.

    “Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius”
    Seems rather on the low side considering that temperatures in the Antarctic was at least 17 degrees warmer at the time:
    https://www.pnas.org/content/105/31/10676

    However, since the press-release is intended for journalists they know they can get away with just about anything.

  27. More researchers ignore that the Holocene was much warmer thousands of years ago.

    “These geological records, say Levy and Meyers, suggest significant variability in the size of the Antarctic Ice Sheet driven by the predictable changes in Earth’s astronomical parameters and threshold changes in atmospheric carbon dioxide levels. Prior to this new research, why the ice sheet responded differently to the same astronomical cycles at different times was a puzzle. Linking those cycles to a detailed chemical record suggests that elevated carbon dioxide in the atmosphere”

    They have finally admitted that they are climastrologists.

  28. And unless you have actually been there it is difficult to comprehend just how cold, desolate and glaciated it really is. I know I was surprised even though I had a fair amount of experience from the Arctic. I had visualised something rather like e. g. Nordaustlandet but a bit more so, but reality was very different. The Arctic is a Garden of Eden compared to Antarctica.

  29. Well, now I have read the paper. And what does it amount to? They have made a fairly strong case that the ice volume varies more strongly with the 41 000 year obliquity cycle when the ice volume is smaller, like during the Miocene Climatic Optimum, which seems reasonable. And that is about all.

    The connection to, and data on, sea-ice is weak, to put it mildly, and their correlation of cores that consist mostly of hiatuses “at 10^5 kyr resolution” is laughable. By the way, the peer review must have been even sloppier than usual for Nature not to notice that “10^5 kyr” means 100,000,000, not 100,000 years.

    Incidentally the decrease in glaciation during the MCO was probably due to partial tectonic blockage of the Drake Passage which increased heat flow to Antarctica.

    And of course there is the usual number of idiotic errors in the press release.

    “The ice sheet is so heavy, Bentley and his colleagues discovered, that much of the West Antarctic ice sheet sits on land thousands of meters below sea level”
    Hardly a new discovery and also wrong. The West Antarctic Ice Sheet is sitting on top of a deep Rift Valley, that’s why. Elementary arithmetics would have shown them that the ice-sheet isn’t nearly heavy enough.

    “the West Antarctic Ice Sheet alone contains enough ice to raise sea level by roughly 5 meters.”
    However it wouldn’t, exactly because it is situated on top of that deep Rift Valley. Most of the water would be needed to fill out the hole left by the melted ice. Even a total collapse of the WAIS would only raise the sea level about 3 meters.

    “Earth and its polar regions were much more temperate, with an atmosphere supercharged with carbon dioxide and global temperatures, on average, warmer by 3 to 4 degrees Celsius”
    Seems rather on the low side considering that temperatures in the Antarctic was at least 17 degrees warmer at the time: https://www.pnas.org/content/105/31/10676

    However, since the press-release is intended for journalists they know they can get away with just about anything.

  30. Interesting that the figure of 34 million years is included in the fairy tale. I believe this is when Drake’s Passage formed, enabling the Southern Ocean circulation and connection between the Pacific and Atlantic oceans. The hot Pacific waters flooded into the Atlantic resulting in Atlantic warming and Antarctica eventually freezing.

    In the northern hemisphere, it is interesting that there is a net transport of heat and water from the Pacific to the Atlantic via the Bering Strait. I wonder how it gets back from Atlantic to Pacific? The Strait is only 50m deep so does not need unrealistic increase in land ice to lose that important inter ocean connection.

    The Pacific is Earth’s BIGGEST solar panel:
    https://1drv.ms/u/s!Aq1iAj8Yo7jNgxuJI0wR9QXdgceI
    Climate on Earth is highly dependent on how the heat collected in the tropical Pacific is transported around the globe. Plate tectonics has been a significant driver of Earth’s climate.

  31. I’m afraid arch-cretin Macron the vaginal monologue was at it for hours this evening in Normandie.

    One of his big sales pitches egged on by the sheep, and herded away from the wolves by the CRS and gendarmerie, was to claim you had to buy a NEW diesel car, because old ones should be sold to Africa, because they pollute too much in France.

    The twaddle he talked endlessly in technocratic jargon was interspaced with references to the deadly poison gas CO2, and how France had to make an energy transition from (reliable) nuclear power to putting up stacks more intermittent powering wind farms some of them floating, then claiming the new European grid was so wonderful from Germany to France it solved everything, and very soon there would be giant batteries everywhere to make it work happily ever after…

    Simply delusional, master propagandist or dangerous lunatic?
    This made me so nauseous after watching the train wreck in London, I just had to switch him off.

    then I read this crap:-
    “https://www.liberation.fr/planete/2019/01/15/la-grande-fonte-de-l-antarctique_1703070”

    au secours!

  32. I’ll worry about sea levels when I see panicked UN staff moving their stuff out of their headquarters in Manhattan heading for higher ground. Until then, it’s just noise…..propaganda, really.

  33. True the movement of the Solar system through the universe as the Milky Way galaxy moves, must have some effect, but by far Plate Tectonics must have a far gr eater effect. It is sad that the land mass where todays South Pole now sits, was once the home of Dinosours.

    The World e has seen major changes in both movement of the land masses, plus high and low CO2, plus heating and cooling. Yet todays fortune tellers can tell us with accuracy what is going to happen in the future.

    Why do our Politicians even listen to such idiots ? Unless of course they want to keep us f frightened.

    MJE

    • “Why do our Politicians even listen to such idiots ?:”

      Simple answer, because politicians like Macron, Trudeau etc ARE the idiots.

      (with a hidden agenda you can’t know, but can only guess at.
      They also claim a state monopoly in violence to protect it).

  34. Am I alone in thinking the Carbon Dioxide reference was stuck in there to get funding, and had little or nothing to do with actual study or its findings?

  35. “Antarctic played a big role in amplifying the effects of changes in the Earth’s astronomical motions on the durability and stability of the Antarctic Ice Sheet.”
    ___________________________________________________

    how shall “Antarctic play [] be a big role in amplifying the effects of changes in the Earth’s astronomical motions”.

    Our globe / the shapeless potato / must always be balanced otherwise we would not have a warming problem but would have long since flown out of orbit.

  36. There are 3 Milankovitch cycles, each with their own periodicity. Orbital eccentricity is roughly 100,000 years (combination of a 413,000 year, 95,000 year and 125,000 year cycles), axial tilt is 41,000 years and axial precession of 25,772 years.

    The article stated that the cyclic danger was the combination of the axial tilt and orbital eccentricity. But then they completely skip over where we are in those cycles, and their length. Our axial tilt is decreasing and will reach the minimum in about 9,700 years. Our orbit is becoming more circular, thus making the seasons more even. So, as is typical, they state a true fact, i.e. the right combination of axial tilt and orbit eccentricity will maximize warming at the south pole. But they leave out the part on when that is projected to occur.

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