Study: Landmass shape affects extent of Arctic sea ice

NSIDC Arctic Sea Ice Extent – click to enlarge

Via AGU journal highlights:

Arctic sea ice has retreated significantly in recent years, reaching a record low in September 2007. It is known that the seasonal cycle in Arctic sea ice extent is not symmetric—seasonal ice retreat proceeds gradually during early summer and then accelerates toward end of summer, while in winter, ice growth is rapid at first and then slows later in the season. Scientists have observed that ice cover has retreated far more rapidly in September than during other times of the year.

Some scientists have suggested that this seasonal asymmetry is due to factors such as temperature changes. However, Eisenman finds that the seasonal differences in rate of ice growth or retreat are caused by the geometry of the landmasses surrounding the Arctic Ocean. Because the Arctic Ocean is mostly surrounded by land, coastlines block the southward extent of sea ice growth during the winter, but coastlines have little effect on the extent of ice during the summer.

The author suggests that to better interpret changes in Arctic sea ice, instead of considering sea ice areal extent, scientists should track the line marking the latitude of the Arctic sea ice edge, averaged zonally over locations where the edge is free to move. He finds that this line moves northward or southward at a steady pace over the course of the year, with no seasonal asymmetry. In recent years, this line has been migrating northward at a rate of about 8 kilometers (5 miles) per year, consistent with overall ice loss. The study explains some aspects of the seasonal Arctic sea ice cycle and could help scientists better interpret sea ice evolution in the future.

Title: Geographic muting of changes in the Arctic sea ice cover

Author: Ian Eisenman: Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA and Department of Atmospheric Sciences, University of Washington, Seattle, Washington, USA.

Source: Geophysical Research Letters (GRL) paper 10.1029/2010GL043741, 2010 http://dx.doi.org/10.1029/2010GL043741

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Here’s the abstract:

GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L16501, 5 PP., 2010

doi:10.1029/2010GL043741

Geographic muting of changes in the Arctic sea ice cover

Geographic muting of changes in the Arctic sea ice cover

Ian Eisenman

Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA

Department of Atmospheric Sciences, University of Washington, Seattle, Washington

The seasonal cycle in Arctic sea ice extent is asymmetric. Its amplitude has grown in recent decades as the ice has retreated more rapidly in summer than in winter. These seasonal disparities have typically been attributed to different physical factors operating during different seasons. Here we show instead that the seasonal asymmetries in Arctic sea ice extent are a geometric consequence of the distribution of continents. Coastlines block southward ice extension during winter, thereby muting changes in ice extent, but they have relatively little effect at the time of summer minimum extent. We suggest that the latitude of the Arctic sea ice edge, averaged zonally over locations where it is free to migrate, is the most readily interpretable quantity to describe the Northern Hemisphere sea ice cover. We find that the zonal-mean sea ice edge latitude during the 1978–present era of satellite measurements has been following an approximately sinusoidal seasonal cycle that has been migrating northward at an approximately annually constant rate of 8 km/year. These results suggest a change in perspective of the most critical quantities for understanding changes in Arctic sea ice.

http://www.agu.org/pubs/crossref/2010/2010GL043741.shtml

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49 thoughts on “Study: Landmass shape affects extent of Arctic sea ice

  1. My big question would be to Judith Curry, if she happens to drop in on this thread:
    How does the AAC affect/interact/limit the Antarctic Sea Ice?

  2. If at first you don’t succeed, try try again.
    I guess since ice thickness and rotten ice are no longer in the picture, zonal averaged whatnots must be found.
    We need to see the data; or maybe it is a model thing once more?
    I am curious how cherry picking can be avoided in an area with so many lace like landmasses when one defines “northwards” and “soutwards”.

  3. Retreat is faster in early summer than late summer. It takes about 10 seconds looking at any of the graphs to realize that maximum rate of retreat occurs when the sun is highest. In September the sun is low and retreat occurs more slowly.

  4. Landmass shape affects extent of Arctic sea ice
    Think next time, a deeper research, will blame Whiskey instead.

  5. “Arctic sea ice has retreated significantly in recent years, reaching a record low in September 2007”
    No it didn’t, it reached a 30+ year low. The record low is none.

  6. This study is like throwing money at a proposal to discover that warm loving birds migrate in the winter. Of course land edges affect ice movement. What would be far more interesting is to study Arctic current affects from El Nino waters since 1978 as well as the AO pressure patterns (IE wind direction) with this northern migration of the ice edge in September. Bet the migration of the Northern edge is weather and oceanic current related and could be modeled without the assumed warming of CO2.

  7. And what about the multiyear ice?
    If the area were more, but it was all new ice, how would this compare with less ice but mostly multiyear? The first would indicate a more dynamic system, while the other would appear to have less drastic extremes.

  8. How about lower layers atmospheric circulation and how relief above 1500m do affect it? This is already well known to those who read Leroux…

  9. “The results suggest…”. I thought the science was settled?
    Maximum rate of retreat occurs near the end of June. How curious.

  10. Because we are getting closer to an ice-free Arctic (giggle), the Sea Ice Extent graphs should really be scaled from 0.0 to 16.0 million, not 4.0 million to 16.0. Then we can watch the decline.

  11. I have a similar problem with my icemaker. There’s this little wire thingie that keeps ice from being produced when the bin is full. I suspect it’s controlled by freezer warming.

  12. Pamela Gray says
    “…What would be far more interesting is to study Arctic current affects from El Nino waters since 1978 as well as the AO pressure patterns (IE wind direction)…”
    Yes, exactly. It’s all about the wind. Which way is the wind blowing? How hard, and for how long? The wind piles up the ice and snow when it blows towards the land and thins it when it blows towards the sea. It has nothing to do with temperature. That’s why all those global warming people make such idiots of themselves by actually going to the Arctic in (yet another) attempt to prove that the Arctic is becoming “ice-free”. They can consider themselves lucky to get out of there alive.

  13. It is time to find a name for these non-studies that are only a shallow re-evaluation of old data designed to lead to a misrepresentation of reality. I wonder how many of the “millions” of “peer” reviewed papers the greenies always talk about are deliberate attempts to generate greenie headlines and have nothing to do with science?

  14. Enneagram says: “Curiously Eisenman means “The Man of the Ice””
    Actually, it means Iron Man. Similar to Eisenhower, a hewer of iron.

  15. Duh. The geographic constraint is obvious by inspection of the sea ice area charts. The lines pass thru or close to “knots” at around mid-May and mid-November every year.

  16. jorgekafkazar says:
    September 13, 2010 at 1:41 pm
    However the German prefix EIS means ICE. It would really mean the Ice-cream salesman 🙂 (because the suffix mann denotes craftmanship or occupation, like in gold-mann )

  17. Enneagram says:
    September 13, 2010 at 1:53 pm
    jorgekafkazar says:
    September 13, 2010 at 1:41 pm
    However the German prefix EIS means ICE. It would really mean the Ice-cream salesman 🙂 (because the suffix mann denotes craftmanship or occupation, like in gold-mann )

    No Enneagram,
    Here you are wrong.
    I am a native German speaker, so I should know 🙂 .
    The prefix “Eisen” means simply Iron. The suffix “mann” just means ‘man’, nothing else. It has nothing to do with craftmanship or occupation. Eisenmann literally means Iron-man.
    If it were “man of the ice”, it would be “Mann des Eises”. Ice-man would be Eismann, but not Eisenmann.

  18. KLA says:
    September 13, 2010 at 2:09 pm
    Then, perhaps your ancestors named Iron -eisen- after “as hard as Ice-eis- ?
    🙂

  19. Over long periods of geological time, looking at the relative locations of the continents – particularly the location of the north part of the Gulf Street and the varying widths and depths of the GIUK ocean gaps over time! – would be very important.
    But in the past 12,000 years – the current Ice Age period we are actually in (or the two ice ages we are between, or the ice age we are beginning to enter, depending on how you look at it) continental drift is not a factor.

  20. Okay, I read the abstract. Okay, the Arctic is more or less a closed basin with those large islands and inconvenient continents forming its margins. Okay, the sea ice is effected by seasonality. Okay, the greatest marginal changes occur where not physical blocked by some land mass or another. “…These results suggest a change in perspective of the most critical quantities for understanding changes in Arctic sea ice.” Well, maybe yes, maybe no or maybe some . From the abstract alone, I am shall I say skeptical and unconvinced. Nothing given here demonstrates that this “perspective” is in any way critical let alone most so, then any other.

  21. It’s the AMO. As long as it keeps injecting warm waters into the Arctic Sea we can expect reduced ice coverage. As the Warm AMO has 5 to 10 years yet to go, “the big chill” should not be expected soon. It will come eventually, however.
    Yet, even with a warm AMO, the current La Nina will replace the El Nino, (with the appropriate lag-time,) and also this years crop of hurricanes will suck a lot of heat out of the Atlantic, so I expect an increase of ice next year. I guess you could call it, “a cold phase of the warm phase of the AMO.” Still, it will be nothing, compared to the actual cold phase of the AMO, ( let alone “a cold phase of the cold phase of the AMO.”)
    Once the AMO kicks into its cold phase, with the PDO still in its cold phase, it will become so obvious that the amount of arctic ice is largely determioned by “cycles” and not “CO2” that much Alarmism will be laughable. However it will be too late to retreat from radical policies, if you don’t get out and vote now.
    Remember in November, and tomorrow too.

  22. Steve from Rockwood says: September 13, 2010 at 12:18 pm
    Maximum rate of retreat occurs near the end of June. How curious.

    Around June 21st?

  23. There was certainly periods when there no landmasses (and only deep ocean depths) near the North Pole. In periods when the climate was not extremely cold, there would have been almost no sea ice at the North Pole (maybe only in the depths of the winter).
    Why? Because ocean currents would have been constantly sweeping the ice out to melt at lower latitudes (or more accurately sweeping the colder surface ocean water out to warm up at lower latitudes). The oceans are going to try to balance out any temperature differentials as long as there is sufficient access to the poles (or more accurately, thermodynamics will).
    This turns out to be an important factor in the overall temperature of the Earth – without continents at or near the poles, and especially with sufficient deep ocean outlets and inlets into the polar regions, there is very little sea ice and the overall global climate is warmer because there is no Ice Albedo (and maybe no ice anywhere at all) on the planet.
    Pangea at 260 Mya is a good example of this situation (and temperatures were most likely at the highest levels in Earth history).

  24. One factor about the Arctic Basin not mentioned it its bathymetry. The edges of the continental shelves define a deep basin, isosceles in shape, with a base extending from north of Svalbard to the Lapetz Sea (check Google Earth). The basin is clearly defined at http://geology.com/world/arctic-ocean-bathymetry-map.shtml.
    It may be my imagination, but nearly every time I see a map/composite satellite image of summer ice, the bulk of ice is centred over this deep. If there is areal contraction, it is along the continental shelves. Is there a deep pool of cold water in the basin little affected by intrusions of the Gulf Stream, etc., that helps maintain the ice cover?

  25. I know what you mean Mr Illis but I would have said the highest temperatures were shortly after the Thea encounter.

  26. Phil’s Dad says:
    September 13, 2010 at 6:56 pm
    I know what you mean Mr Illis but I would have said the highest temperatures were shortly after the Thea encounter.
    ——-
    Okay, I’ll bite the bait- what is the Thea encounter?
    Of course, right after the asteroid struck at 65 Mya, atmospheric temperatures rose to hundreds of C and everything that could burn, did burn including the dinosaurs, but …

  27. Bill Illis says:
    September 13, 2010 at 6:29 pm
    In that case, an Ice-free Arctic would be a good thing, as a lot of temperature extremes would be cancelled out.
    No more crop killing hailstorms, orchard freezing, wheat rotting extremes. Not to mention the hurricanes & tornados might not be around so much.
    What bothers me is that a lot of these young scientists are getting thier PhD’s on the back of global warming studies. Nobody is studying (or funding) global cooling. One-track minds.

  28. Bryn says:
    September 13, 2010 at 6:49 pm
    One factor about the Arctic Basin not mentioned is its bathymetry. The edges of the continental shelves define a deep basin …
    ——-
    This is a very important point. Thanks Bryn. It is really the continental shelves which define the Arctic basin. The colder, denser surface ocean will sink to the depths (which could be over 5000 metres if the ocean goes that deep) and the continental shelves define where this colder denser water can sink to.
    If you look at the bathymetry as Bryn noted, the European/Asian continental shelf extends far out into the Arctic basin. Go back 2.6 Mya before the ice ages started and almost all of this area was likely above sea level. Norway was 10 ten times bigger at that time. Look at the bathymetry and one sees there is almost no deep ocean depths where the cold dense Arctic ocean water can sink into and flow out of into the rest of the Atlantic. It is partially trapped by the topography.
    The ice generated in the ice ages suppressed this continental shelf landmass area and Europe probably extended to Svalbard and the Franz Josef Islands before the ice ages started at 2.5 Mya. Europe was twice as big.
    North Africa, as well, was pushed below sea level at 440 Mya when it was centred over the South Pole and massive glaciers built up there. This issue changes the landmass to an area where land glaciers can build up on (to as high as 4 kms high) to an area where only sea ice can build up (4 or 5 metres high only).
    Put this all together and calculate the Ice Albedo that results (80% of sunlight reflected back to space from a 4 km high land glacier versus 50% reflected by a partially-sea-ice-covered-continental shelf region and 25% reflected by a non-ice-covered-normal region) and this almost explains the Earth temperature history by itself. If one runs the numbers, this explains Earth temperature history almost completely by itself. 80% of the sunlight reflected versus 25% of the sunlight reflected is a huge difference.
    Look at the continental shelves versus the current above sea level maps. All of Hudson Bay, the North Sea, the Barents Sea, the Kara Sea, and the East Siberian Sea were likely above sea level before the ice ages started.
    And this issue is hard to explain properly.

  29. Here’s a thought: There are no ocean currents on dry land, but there are such currents around Greenland and Antarctica.
    As we all know —or should by now— ocean currents convey, release, and collect heat in one way or another, affecting the regions where they happen to traverse adjacently.
    Perhaps if Greenland were essentially connected at the hip to someplace Canada, the ice accumulation would be far different? The rain in Spain falls mainly in the plain … and all that rot.
    Iceland receives lots of warmth from the southerly currents as do several other islands in the that region.
    Ergo, attributing ‘shape’ to that matter of ice collection is, well, rather ‘contrived,’ when all other factors have not been properly assessed.

  30. DesertYote says:
    September 13, 2010 at 12:54 pm
    It is time to find a name for these non-studies that are only a shallow re-evaluation of old data designed to lead to a misrepresentation of reality. I wonder how many of the “millions” of “peer” reviewed papers the greenies always talk about are deliberate attempts to generate greenie headlines and have nothing to do with science?
    ___________________________________________________
    Your suspicions are correct.
    Dr Scott Armstrong did some great papers on that subject. They are really quite humorous too. The study I liked best was where a scholarly looking actor give a gobblety gook talk to a bunch of psychologists and social workers and had them rate the talk afterwords. The talk was rated very highly even though it was unintelligible nonsense. Unintelligible Management Research and Academic Prestige
    Here is what he had to say about peer-reviewed papers:
    “For young academics who wish to be published in such journals, Armstrong said, “the factors that would seem to be a deadly combination would be choosing an important problem and obtaining surprising results.”
    Other studies, Armstrong said, indicate that obscure writing helps those who have little to say. And having little to say may also be an advantage, especially if the author withholds some significant data. “This will allow the researcher to continue publishing slightly different versions of the same research,” which Armstrong says is a common practice… “
    Plain Prose: It’s Seldom Seen in Journals
    “Bafflegab Pays” http://marketing.wharton.upenn.edu/documents/research/Bafflegab%20Pays.pdf
    The Seer-Sucker Theory: The Value of Experts in Forecasting “…George Strickler found that although people with high expertise rejected valid disconfirming evidence, subjects with much less expertise improved their accuracy by using disconfirming evidence…The advice to seek disconfirming evidence is not new – it is the principle behind “objective” scientific experiments. Unfortunately, it is not often used even by scientists, and training does not seem to help. In a study using Wason’s 2-4-6 problem, Mahoney and DeMonbreun found that the aversion to disconfirming evidence is just as prevalent among physical scientists as it is among psychologists.”
    http://www.forecastingprinciples.com/paperpdf/seersucker.pdf
    More papers can be found here, you will never look at a “peer reviewed paper” the same way again after reading some of these papers by Dr Armstrong: http://marketing.wharton.upenn.edu/people/publications.cfm?id=226&current_flag=0

  31. If the sea levels drop, then the foothold of the Arctic Ice can expand, and the ocean currents will be somewhat thwarted.
    The shelf regions in the Arctic may then pick up ice mass, and that’s at least one way to get the Laurentide going.
    As long as warming is going on, the oceans can deliver warmer water up there, thus the freezing/ice cap/sea level drop thing is put on hold.
    Fail to warm and perhaps the process of Ice Age building can begin.
    Please don’t applaud, send lots of Study Money.

  32. 899 says:
    September 13, 2010 at 8:21 pm
    Yes, there’s a thought, and it beats the stuffings out of stale warming studies.

  33. I’m starting to feel like a broken record, but I feel Hapgood was correct about pole shift, just didn’t understand why.
    http://www.viewzone.com/changingpoles22.html
    “UPDATE 2010:
    Earth’s north magnetic pole racing towards Russia due to core flux
    Washington, December 25 : A new research has determined that Earth’s north magnetic pole is racing toward Russia at almost 40 miles (64 kilometers) a year due to magnetic changes in the planet’s core.
    The core is too deep for scientists to directly detect its magnetic field. But researchers can infer the field’s movements by tracking how Earth’s magnetic field has been changing at the surface and in space.
    Now, according to a report in National Geographic News, newly analyzed data suggest that there’s a region of rapidly changing magnetism on the core’s surface, possibly being created by a mysterious ‘plume’ of magnetism arising from deeper in the core.
    ‘It’s this region that could be pulling the magnetic pole away from its long-time location in northern Canada,’ said Arnaud Chulliat, a geophysicist at the Institut de Physique du Globe de Paris in France.
    Magnetic north, which is the place where compass needles actually point, is near but not exactly in the same place as the geographic North Pole.
    Right now, magnetic north is close to Canada’s Ellesmere Island.
    Navigators have used magnetic north for centuries to orient themselves when they are far from recognizable landmarks.
    Although global positioning systems have largely replaced such traditional techniques, many people still find compasses useful for getting around underwater and underground where GPS satellites can’t communicate.
    The magnetic north pole had moved little from the time scientists first located it in 1831.
    Then in 1904, the pole began shifting northeastward at a steady pace of about 9 miles (15 kilometers) a year.
    In 1989 it sped up again, and in 2007 scientists confirmed that the pole is now galloping toward Siberia at 34 to 37 miles (55 to 60 kilometers) a year.”
    Here’s a old link from NASA,
    http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.html
    The pole kept going during the 20th century, north at an average speed of 10 km per year, lately accelerating “to 40 km per year,” says Newitt. At this rate it will exit North America and reach Siberia in a few decades.
    ” Keeping track of the north magnetic pole is Newitt’s job. “We usually go out and check its location once every few years,” he says. “We’ll have to make more trips now that it is moving so quickly.”
    If someone could please explain to me why a constant north shiting pole wouldn’t have an effect on the seasonal ice sheet creation/climate even with tracking showing Earth’s magnetic field at the surface and in space?
    Thanks,
    Lance of BC

  34. Lance of BC says: September 14, 2010 at 4:47 am
    ………Earth’s north magnetic pole racing towards Russia due to core flux……….
    Magnetic North pole shift is a bit of a misconceptions.
    At the high latitudes vertical (Z) component of Geomagnetic filed GMFz makes more than 90% of total filed. Currently at the geographic NP (90N): Vertical Component Z = 56,589.0 nT; Total Field F = 56,622.4 nT (data from NOAA)
    GMFz has two peaks in the Northern hemisphere, on the first graph, top of the page http://www.vukcevic.talktalk.net/NFC1.htm
    marked with blue and green crosses, while the magnetic‘pole’ is marked with a red star.
    These two peaks located at approx 60N, 100W and 64N, 107E, have hardly moved (only few degrees) during the last 300 years or so,
    http://www.vukcevic.talktalk.net/LFC.htm
    but their intensities have changed, the Siberian peak increasing while the Canadian one falling, giving an impression of the ‘pole’ moving towards Siberia.
    In the mid-1990’s two peaks were of equal intensity.
    Any link to the climatic changes is translated directly through the Arctic . See rest of
    http://www.vukcevic.talktalk.net/NFC1.htm

  35. The builders of Stonehenge were on the right track, as they laid out the effects driving the end of the last ice age. Laid out the basic structure as it was changing from tundra to grasses. Built the finished format of the structure during the time trees started to become common. Once the land recovered enough to be farm able consistently, they quit wasting resources on the building of structures to teach others, and went back to farming again.
    I can’t wait for the AGW peeps to roll up their sleeves and start working on long range forecasting, to better enhance the use of crop rotations that make sense, to help maximize the food production.

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