It’s the Trend, Stupid

Anthony Watts posts that Southern Hemisphere Sea Ice Extent Anomaly for November was a record high for the NSIDC data set. He also mentions that this year saw record highs in Southern Hemisphere ice extent for June, July, and August as well.

Watts also complains that “Oddly, they have a plot for extent, and a data file for area, but no plot for area or data for extent. Seems backwards, doesn’t it? Maybe I’ve missed something and they are in some other FTP folder?” This makes me suspect that he hasn’t looked at the actual data files, because those files with “area” in the name contain data for both area and extent.


Monthly average southern hemisphere sea ice extent for November was indeed the highest on record (for the NSIDC satellite data):

For the northern hemisphere, this November was only 2nd-lowest on record:

Which TREND do you suppose is greater?

Monthly average southern hemisphere sea ice extent for June was indeed the highest on record (for the NSIDC satellite data):

For the northern hemisphere, this June was also a record, the lowest in this data set:

Which TREND do you suppose is greater?

Monthly average southern hemisphere sea ice extent for July was indeed the highest on record (for the NSIDC satellite data):

For the northern hemisphere, this July was only 2nd-lowest on record:

Which TREND do you suppose is greater?

Monthly average southern hemisphere sea ice extent for August was indeed the highest on record (for the NSIDC satellite data):

For the northern hemisphere, this August was only 2nd-lowest on record:

Which TREND do you suppose is greater?

One more thing — both the rapid decrease of arctic sea ice, and the slight increase of antarctic sea ice, were predicted in advance. By those guys who keep telling us that global warming is real, is man-made, and is dangerous.

P.S. The Rabett has useful information on this.

UPDATE:

As requested, here are sea ice extent anomalies for both hemispheres on the same graph, for each of the months mentioned. Anomalies are relative to the entire data set. For November:

For June:

For July:

For August:

UPDATE 2:

Also by request, here’s a comparison between N.Hem September and S.Hem March extent anomaly:

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32 responses to “It’s the Trend, Stupid

  1. Hi, just a thought, but the trend ‘eye-balling ‘ would be more scientific if the NH and SH scales were constant especially to estimate comparative magnitudes of change.

  2. This is like one of those “spot the difference” things we did as kids, looking at two versions of the same cartoon. The scale is not the same (though there is more ice surrounding Antarctica, the scale for the Arctic is bigger to accommodate the 2 million sq. km. change.) So, WTF with WUWT? Our pal Anthony must have a well-thumbed copy of “How to Lie with Statistics”, one of my favorite books.

  3. I found a pretty well written explanation of why the sea ice is increasing down there.

    Good post, although a bit repetitive.

  4. William: while absolute trends are interesting, for me the key point is trend relative to natural variability, for which normalized plots (kind of like the above) are the best.

    -M

  5. We’re having global cooling without a doubt!

  6. “One more thing — both the rapid decrease of arctic sea ice, and the slight increase of antarctic sea ice, were predicted in advance.”

    Strange that!
    This prediction seems to have been missed by the IPCC and all those reviewers of its products.
    This is the IPCC view of things and its prediction.

    This is what the IPCC said about Antarctic sea ice in 2001.

    “16.2.4.2. Sea Ice in the Southern Ocean
    Antarctic sea ice is not confined by land margins but is open to the Southern Ocean. Sea-ice extent contracts and expands on an annual cycle in a roughly concentric zone around Antarctica. The ultimate extent is controlled by a balance of air temperature, leads, wind direction, upper ocean structure, and pycnocline depth. Some of these parameters are controlled in the atmosphere by the relative position of the subpolar trough with respect to the sea ice. In the ocean, variations in the Antarctic Circumpolar Current are important. The extent and thickness of Antarctic sea ice are sensitive to the depth and thermal properties of overlying snow, about which relatively little is known.

    A reduction in Antarctic sea ice volume of about 25-45% is predicted for a doubling of CO2, with sea ice retreating fairly evenly around the continent (Gordon and O’Farrell, 1997). This CSIRO model assumes a 1% yr-1 compounding increase of CO2, corresponding to global warming of 2.1°C. Using a similar but modified model that has a higher albedo feedback and predicted global warming of 2.8°C, Wu et al. (1999) calculate a reduction in mean sea-ice extent of nearly two degrees of latitude, corresponding to 45% of sea-ice volume. These estimates do not represent the equilibrium state, and sea ice can be expected to shrink further, even if GHGs are stabilized.”

    Here is what was said by the IPCC in 2007…………

    ” Highlights from the IPCC Working Group I Summary for Policymakers of “Climate Change 2007: The Physical Science Basis”

    “What can we expect to happen?”…………..“Sea ice is projected to shrink in both the Arctic and Antarctic.”

    Surely we can’t be ‘past posting’ here!

    Alan

    [Response: Those predictions are for the long term change -- doubling CO2 won't be reached for another 50 years or more. The predictions of Manabe et al. (see the post by the Rabett linked to above) are for increased Antarctic sea ice as a transient response (in fact, comparing the transient to the equilibrium response is one of the points of their research). The short-term increase in Antarctic sea ice was predicted in advance, and has been observed.

    I expect they'll be right about the long-term change also.]

    • In support of what Tamino said (although in regards to general climatic response…not specifically sea ice), in the book “Global Warming: The Hard Science” by L.D. Danny Harvey published in 2000, he says (in Section 11.2 Regional Patterns of Projected Transient Climate Change),

      Among the important differences between the steady-state patterns of climatic change (found in experiments with AGCMs) and transient patterns of climatic change are:

      * a less than average warming in the North Atlantic and Antarctic Circumpolar Ocean in the transient case, whereas the steady-state case shows a polar amplification (Manabe et al., 1991; Murphy and Mitchell, 1995); …

      The references are to:

      S. Manabe et al., “Transient responses of a coupled ocean-atmosphere model to gradual changes of atmospheric CO2, Part I: Annual mean response, ” Journal of Climate 4, 785-818 (1991).
      J.M Murphy and J.F.B. Mitchell, “Transient response of the Hadley Centre coupled ocean-atmosphere model to increased carbon dioxide. Part II: Spatial and temporal structure of response,” Journal of Climate 8, 57-80 (1995).

      • This paper (Manabe) was published almost 20 years ago. When it was published, there were 12+ years of satellite observations that showed increasing ice (extent). I’m not so sure this was a prediction as much as it was an explanation of observation using computer models. I may have missed it, but there’s nothing in the paper predicting the length of this transient phase, but since warming began in 1900 or so I guess we can conclude this transient, short-term, phase is somewhere around 110 years old(?!).

        [Response: Complete, total, unadulterated bullshit. You just made it up without even bothering to find out whether you were right or wrong.

        When Manabe et al. was published the Antarctic sea ice had not yet shown an increasing trend. Not even close. As for the century-long trend in Antarctic ice, that's a strong decrease, not increase. And Manabe et al. are clearly prognosticating the future, not the past.]

      • Well, admittedly I only eye-balled the extent graphic, like [edit]

        [Response: No, I'm not interested in hosting a link to a idiotic document from Icecap.]

        It sure looks like an increase from 1978 to 1991 to me, or maybe 0 increase/loss, but I’ll take your word for it that it was “not even close.” I certainly wasn’t trying to be deceptive.

        [edit]

        [Response: Drop the innocent routine. You decided to spew such stupidity as "this transient, short-term, phase is somewhere around 110 years old" -- a moronic claim, wrong in every regard, and like the claim that there was already 12+years of increase in the satellite record, utterly false but you didn't even bother to confirm or deny, you just spewed.

        I guess the changes in sea ice are such stark and compelling evidence of global warming that denialists have only one answer: make up some total bullshit. But then, that's all they've got.]

      • Tamino,
        If global warming has been going on since 1900, then why does the ‘transient effect’of increasing ice begin 90+ years later?
        You can’t have it both ways, either Manabe is predicting something that miraculously didn’t happen for nearly 100 years and has been going strong for the last 20, or the paper wasn’t predicting a friggin’ thing.
        If I’m right you’ll snip this post, probably completely. I don’t give a rats ass about winning some public debate – just snip it and I’ll know you don’t have an answer.

        [Response: If you read the paper maybe you'd know. If you had analyzed Antarctic sea ice data maybe you wouldn't have made such stupid comments about 12+years of increase. If you had paid attention to this blog you'd already know that Antarctic sea ice had been in decline for a century when Manabe et al. was published. You did none of that, because you just want to push your agenda and you're either too lazy, too stupid, or too dishonest to find out the truth. Or all three.

        What part of "prediction" do you think refers to the past? All you've been able to do is deny reality in a way that embarrasses you and your claims. I doubt you're capable of admitting the truth, even to yourself.

        Denialists are pissed off that they have no explanation for the reduction of Arctic sea ice, so they point to Antarctic sea ice. But when it's shown that the (slight) recent increase is not contradictory to global warming, they either tell outright lies or make up stupid bullshit.

        I do care about morons posting falsehoods when they have no answer to the astoundingly powerful evidence that global warming is real. That's because I care about future generations.

        But I don't give a rat's ass about hosting further comments from morons. Especially those who aren't just mistaken, they're liars.]

      • I think KenM can best be answered by pointing out that it’s complicated. Anyone looking for trite little convenient bites of science should look elsewhere.

        Why do deniers think they can overturn climate science by jumping in the deep end and discovering that they don’t understand the most complicated parts of climate science?

        Stay in the kiddie pool, folks. Learn the basics.

      • For those following this subthread with some confusion about what is being said, the first part of the Manabe paper is here:

        http://journals.ametsoc.org/doi/pdf/10.1175/1520-0442%281991%29004%3C0785%3ATROACO%3E2.0.CO%3B2

        If I’m reading the paper correctly, it has nothing to do with what Ken is trying to assert, as Tamino suggests. Basically, it initializes models to real-world conditions as of 1990 or so, then looks at what happens if CO2e increases 1%/yr for a century, and what happens if it decreases similarly.

        It’s not trying to “predict the future” from 1990ish–or to “explain the past,” either–but to examine (as the title says) the transient climate response to CO2e forcing–at the time, work had focussed on equilibrium response.

      • Oh, yeah–the Cryosphere Today Southern Hemisphere graph is here:

      • KenM says, “You can’t have it both ways, either Manabe is predicting something that miraculously didn’t happen for nearly 100 years…”

        Ah, interesting that when he doesn’t understand something, the first idea that leaps to his mind is “magic” or “miracles”. Not a very scientific type, are you Ken?

        “…and has been going strong for the last 20, or the paper wasn’t predicting a friggin’ thing.”

        Why not actuall read it and find out. Dude, you don’t even know what you are arguing against!

    • This is an interesting point. The slower warming in the Antarctic was, of course, predicted long ago. And now we are observing it.

      This may have implied a much slower (or insignificant) reduction in Antarctic sea ice in the short term.

      I’m not sure, though, that an actual small increase in ice was predicted – and the reason I think this is because it took so long to understand why the increase is occurring. We still can’t say for sure. I think there is still some genuine disagreement about the causes, and models don’t yet do well with this detail.

      The long term response, however – well, that’s just so obvious that only the most moronic of deniers try to avoid it. Ice melts if it gets hot enough. Duh.

    • Alan Millar,

      Well, will you apologise for your misrepresentations? Not just to the people here but also to Luis Dias in the WUWT thread? Luis accepted your quotes in good faith so it is now up to you to come clean and put the record straight.

    • This is from page 18 of the AR4 SPM.

      • Projected warming in the 21st century shows scenario-
      independent geographical patterns similar to those
      observed over the past several decades. Warming is
      expected to be greatest over land and at most high
      northern latitudes, and least over the Southern Ocean
      and parts of the North Atlantic Ocean (see Figure
      SPM.6). {10.3}
      • Snow cover is projected to contract. Widespread
      increases in thaw depth are projected over most
      permafrost regions. {10.3, 10.6}

      • Sea ice is projected to shrink in both the Arctic and
      Antarctic under all SRES scenarios. In some projections,
      arctic late-summer sea ice disappears almost entirely
      by the latter part of the 21st century. {10.3}

      It is clear which period is being referred to, so why does Alan Millar pretend that it refers to some other, much shorter one?

  7. As requested, I’ve updated the post with a graph for each of the months referred to, showing N.Hem and S.Hem ice extent anomaly on the same graph, on the same scale.

  8. Somebody tell me why exactly we are matching month to month anomalies for Northern and Southern hemispheres when their insolation and sea ice patterns are six months offset?

    What I want to see is how much sea surface is exposed to sunlight for the 90 days following the summer solstice in BOTH hemispheres and whether that value is increasing or decreasing over time.

    Since there is a large variable due to the relative distribution of daylight hours in the Arctic Ocean and the Antarctic Circumpolar current that would have to be factored in also.

    In a nutshell is the globes total oceanic surface area absorbing sunlight going up or down? What the Antarctic sea ice is doing this year in early summer matters bupkiss compared to that question.

    Anthony Watts is practicing the fine art of distracting the class with questions that will not be on the test.

    • I was wondering the samething. What does the S Hemisphere March extent/area data look like? And how does it compare with the September N Hemisphere extent/area data?

      [Response: See UPDATE 2 (at the end of the post).]

  9. Watching the Deniers

    Having so clearly got it wrong with his predictions on Arctic ice, Watts et.al are now playing bait-and-switch in a desperate attempt to make his readers forget how poor his actual record is.

    “Oh look, there’s more ice here! Oh, the Arctic? Never heard of that place called the Arctic!”

    And as others have noted conditions in the Antarctic were predicted. Also predicted, decrease in Arctic ice.

    So that’s 2-0 for “science”.

  10. I suppose we can trust Alan Millar to correct himself on this subject, the other places he’s posted his error?
    http://www.google.com/search?q=“alan+millar”+”sea+ice”++IPCC

  11. This makes me suspect that he hasn’t looked at the actual data files, because those files with “area” in the name contain data for both area and extent.

    Of course you are wrong, Tamino. We all are just unable to read properly. Watts has updated his post:

    Oddly, they have a plot for extent, and a data file for area, but no plot for area or data for extent. I meant to say: Oddly, they have a plot for extent, and a data file for area, but no plot for area or data file for extent. They do have both data included in the file named “area.txt”. Seems backwards, doesn’t it?

    Of course, Watts was only indicating, that NSIDC should have put the data into seperate data files. Of course. And I’ve got a bridge to sell.

    So Watts is not even able to admit the simplest, most obvious mistake of his own, but instead is trying to weasle out of an admission of error and trying to turn it into yet another (weak) attack.

  12. Nicely shown Tamino. On Oct 16 you did a history of sea ice part 1; here’s looking forward to part 2.

  13. Benjamin Franz

    A few weeks ago I put some charts together to show the trends and a composite of northern/southern sea ice minimums added together.

    Composite Artic+Antarctic Sea Ice Extent Summer Minimums

    Trends in Arctic Summer (September) Sea Ice Extent

    Trends in Arctic Summer (March) Sea Ice Extent

  14. Benjamin Franz

    Oops. The third link should be labeled ‘Trends in Antarctic Summer (March) Sea Ice Extent’.

  15. Watts knows he’s full of bunk and barks more than a small dog trying to hide it. Global Sea Ice area and anomaly graphs are available on the Cryosphere Today website and have been for years. Despite the fact that the total global sea ice extremely noisy a quick glance at the anomaly graph shows a clear trend downward. To make any kind of claim that Anarctic Sea Ice is making up for losses on Arctic Sea Ice the anomaly graph would have to appear to be flat. That’s not the case.