More lies, damned lies and statistics…

Over at Open Mind, Tamino has done it again – pointing out errors in the “skeptic” so-called science used to deny global warming.

He reviews the work of Steven Goddard posted at Watts Up With That, which claims that it’s getting increasingly snowy over the Northern Hemisphere — an increase according to his data of 100,000 km2 / year. Whew! That’s a lotta snow.

Here’s some commentary from the post Northern Hemisphere Snow Extent Second Highest On Record:

As discussed on WUWT, the implication is that Northern Hemisphere snow cover has only extended this far south one other time, since Rutgers University started keeping records.  Additionally, North American snow extent broke its all time record last week. Canada is normally completely covered with snow in the winter (except for Olympic venues) so the implication is that the US had more snow last week than has been seen in at least the last 44 years.

Two of the fundamental precepts of global warming theory are that the tropics are supposed to expand, and the Arctic is supposed to warm disproportionately and shrink…

Ice age or a fiery tipping point?  What do readers think?

Thing is, he’s cherry picking. He picked only the snow extent in December – February for 1989 – 2010.

Hmm.

Tamino, ever skeptical and curious, re-examines the same data but for all months of the year and for the entire record, starting in 1967.

Guess what?  A statistically significant decline in snow extent in the Northern Hemisphere of 37,000 km2/year!

Go figure!

More junk science at WUWT…

Whoda thunk?

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17 Responses to “More lies, damned lies and statistics…”

  1. Not the first time Goddard has done this sort of thing.

    http://scienceblogs.com/deltoid/2008/08/about_that_arctic_sea_ice.php

    Winter snow (at least in some locations) is expected to increase as a result of global warming. Warmer atmosphere -> more precipitation.

    On a somewhat related note, I found this to be an interesting study:

    Warmer Planet Temperatures Could Cause Longer-Lasting Weather Patterns

    “It is anticipated that in a warmer world, blocking events will be more numerous, weaker and longer-lived,” Lupo said. “This could result in an environment with more storms. We also anticipate the variability of weather patterns will change dramatically over some parts of the world, such as North America, Europe and Asia, but not in others.”

    http://www.sciencedaily.com/releases/2010/02/100218125535.htm

    and another (I think it’s “in press”):

    http://www.scientificamerican.com/ article.cfm?id=still-hotter-than-ever

    http://www.people.fas.harvard.edu/~tingley/mean_variance.pdf

    The main point of the paper is to discuss regional variation in the northern hemisphere and a link between warmer temperatures and greater variation. The conclusion for recent warmth is even more anomalous than previous estimates.

    “According to the proxy records, the 1906-1990 period is warmer than the
    medieval period, but the spatial variability is not significantly different within the two periods.”

    I found the following line to be quite interesting:

    “If, as expected, surface temperatures continue to rise in the future, we expect, based on past trends, that the spatial dispersion of the surface temperature distribution will likely increase as well.”

    Figure 1 caption:

    “Bottom panel: an increase in both the mean and the standard deviation leads to much larger areas of high temperatures, with
    a small (relative to the upper panel) reduction in the areas of low temperatures.”

    So if I read that right, way more heat extremes, but not as much of a benefit in reduced cold extremes. It tends to provide some evidence for the general “a warmer climate is a more variable climate” notion, with regards to temperature variation in this case.

    • Up here north of 49, we know that it won’t snow when it’s really cold – as in -45C cold. “It’s too cold to snow” is a common comment. Apparently, people in the ‘skeptic’ camp don’t understand the basics of weather, let alone climate…

  2. So, hang on a minute! Who’s more tricky here Tamino or Watts?

    Whose starting points and decades are more important is what it all boils down to. Tamino likes 1967 , but disses 1989 to 2010 and avoids 1940 to 1970 like the plague.

    The AGW apocalypse hypothesis projects the arctic will be ice free in 5 to 30 year and much of Manhattan, Bangladesh and Florida will be under water, depending on who you ask, but all the recent trends show no warming and increased snow cover and you guys aren’t a little teeny bit curious? The century is 10% over already and the GMC have seriously missed their all their warming projections since the 1980′s. We’ll never get to plus 5c or even 2c by 2100 at this rate.

    And tamino cherrypicked too. There was that mysterious cooling period from about 1940 to 1970 he cut out of his graph.

    Of course, we will never talk about how much of the warming last century was due to the planet’s recent emergence from the Little Ice Age.

    Nor is fashionable to acknowledge that the long wave trend is for interglacial warming. Slow warming is the norm, not the exception.

    We won’t even mention the margin of error for continental snow coverage measurement in 1970 was far greater than 40,000km/yr, rendering this whole line of argument BS, which might be why Watt’s chose to start when more robust data was available.

    If the AGW hypothesis has any usefulness as an explanation for observed data then the data better start conforming to the hypothesis a bit more rigorously in the near future. Or perhaps vice versa.

    • Wes, the Dunning-Kruger effect is strong in you. Reading comprehension is fittingly low: Tamino analysed THE ENTIRE RECORD. That record started in 1967. No hiding of data, unlike Goddard’s (it’s not Watts, but he once again allowed the “CO2 snow in Antarctica”-idiot to post again) cherry picking. For example, there is no objective reason to pick 1989 based on data quality. 1986 data is just as good (but doesn’t show an increase). Take 1978 and you have a decrease. Of course, the increase isn’t even nearly significant.

      And interglacials are not known to show “long term warming”:

      All measurements show that we’ve passed the summit long ago.

    • And tamino cherrypicked too. There was that mysterious cooling period from about 1940 to 1970 he cut out of his graph.

      Sorry — wrong, either through ignorance, willful or otherwise. You may need a brush up course on statistics…

      The record starts in 1967. Tamino used the entire record. Watts cherry-picked only the years since 1998.

      • OK, fine. I stand corrected. Records start in 1967.

        Statistically significant, though? What about the margin of error in measuring tens of millions of square kilometers of snow?

        It sounds vast, but 37,000 km2/year decline is a pretty slim margin especially back in the 1970′s when satellite imagery analysis was in its infancy.

        Consider that North America is 24,700,000 km2 with 37,000 km2 of annual snow loss, give or take a margin of error of about the same size (or greater) and you get basically nothing. No really significant trend at all, especially considering that the more recent trend since 1989 (with more accurate measurements, btw) has been shown to be for increasing snow coverage at three times that rate!

        The real issue here is not that continental snow isn’t in a slight long term decline possibly caused by warming. Fine, it might well be. The problem is that the snow coverage is NOT in catastrophic permanent decline, which is exactly what the AGW hypothesis predicts. (Well, at least until increased snow coverage was announced to be new evidence for AGW as well…see below..)

        What do we call a hypothesis that makes predictions which empirical observations do not confirm?

        Furthermore, those tempted to project Tamino’s trend to 2070 to see how much snow coverage will be lost, should also project this trend backwards in time to 1900 as a test to see if the snow coverage regularly extended to Miami and Houston back then.. you know, just to test the soundness of this kind of linear reasoning.

        • “The problem is that the snow coverage is NOT in catastrophic permanent decline, which is exactly what the AGW hypothesis predicts”

          Total strawman. I am a climate scientist and nowhere have i read any prediction that snow cover would experience a catastrophic permanent decline.

          If you are going to comment, comment about what scientists actually are saying, not what you wish they said.

          • Good to meet an expert! ;-) Perhaps you can illuminate the issue…

            “These results suggest that snow cover may be a sensitive indicator of climate change, and that North American snow extent will probably decrease in response to greenhouse gas emissions..”

            http://www.agu.org/pubs/crossref/2005/2005GL023394.shtml

            A real scientist wrote that. Please explain what that means in lay terms?

            And…

            As a layperson, I got the impression that there might be a catastrophic and permanent decline in snow and ice coverage? Pffft, silly me…

            Mann, that’s an awesome graphic!

            So please explain to us, as an expert, how these scenarios based on the dominant AGW hypothesis as certified by the IPCC are compatible with your statement that “nowhere I have read any prediction that snow cover would experience a catastrophic permanent decline…”

            Thank you for your time.

            • There we have Wes George again, showing his amazing dunning-kruger powers.

              Tell us, oh great Wes, where do Frei and Gong claim “catastrophic permanent decline” of snow cover. The other two links don’t even discuss snow cover.

            • Hi Wes,

              The first link is one modeling paper, suggesting that snow cover will decreases in the future under various greenhouse gas scenarios. Where does it suggest that there will be a permanent and catastrophic decline? In fact, that paper specifically points out that 1) there is significant variability across models in their simulation of snow cover extent and 2) most models underpredict snow cover compared to observations.

              The second link is primarily a discussion of the various greenhouse gas emission scenarios the IPCC uses for future climate model simulations. A range of scenarios is necessary, because we simply don’t have a good handle on what the emissions will be in the future, as it will be highly dependent on economic and political decisions. There is no discussion of snow cover.

              The third link shows the temperature projections from a suite of IPCC models across the range of emission scenarios outlined in the second link. I would think people would appreciate this, since it showcases the uncertainty we have for future climate. Again, there is no discussion that I can see about snow cover.

              So, again, your original argument stands as a strawmen. And, maybe their are a some articles that claim a “catastrophic and permanent decline in snow and ice coverage”. But I have not seen these articles, and the general scientific consensus does not support this.

              Incidentally, there is no such thing as a monolithic “AGW Hypothesis”. There are hypotheses regarding climate sensitivity, the radiative impact of increased co2, feedbacks, etc. I would suggest you refrain from saying “AGW Hypothesis” and strawman arguments if you would like to have a respectful discussion.

  3. The fundamental problem with this thread is shameful logic.

    Tamino’s argument is that snow coverage is in long term decline, therefore it must be Human-induced global warming! Fine. That’s a causality fallacy there but let’s say we buy into the linkage.

    Then MarkB and Shewonk chime in that increasing snow coverage is evidence of…wait for it…Anthropogenically driven Global Warming.

    So increasing AND decreasing snow fall is evidence in support of the AGW hypothesis? Ouch.

    Dunning-Kruger Effect, anyone?

    “The Dunning–Kruger effect is a cognitive bias in which “people reach erroneous conclusions and make unfortunate choices but their incompetence robs them of the metacognitive ability to realize it”.”

    http://en.wikipedia.org/wiki/Dunning–Kruger_effect#cite_note-Kruger-0

    • You’re oversimplifying everything and either have no familiarity with Tamino or you’re being deliberately misinformational. If the former, go read his blog — its a must read for anyone who is seriously interested in learning about global warming science. If the latter, well, we’ll just take that into consideration when we read your comments.

      I am not an expert, but this is what I think is the argument against your comments:

      1. Long-term melting of snow is evidence of warming. There is no causality fallacy in play — there is a physical mechanism to explain it. In other words, it’s not a spurious correlation.

      2. Analyses of the causes of that warming indicate that the largest proportion is due to the burning of fossil fuels and release of CO2 into the atmosphere.

      3. Warming also leads to increased water vapor in the atmosphere, which will ultimately result in rain in some warm areas and snow in some cold areas. In fact, warmer air can hold more moisture than colder. Increased snowfall in some areas is in fact one prediction of a warming climate.

      If you look at Antarctica, you will see this in play — some areas are experiencing an increase in snow, while others are experiencing a decline.

      If I’m wrong on this, I hope someone more knowledgeable will correct me.

      • Oversimplification? Ah, my dear or a return to first principles? If one cannot think rationally and construct logical arguments then all the data points in the world become simply a heap of white noise upon which you can project any fantasy you wish.

        1. Long-term decline in continent snow cover could be a sign of warming, True. But correlation in a complex non-linear system such as the Earth’s climate is far far away from causation. In other words, without more evidence, yes, it is a spurious correlation, logically that is. Emotionally it makes perfect sense to the human mind to see correlations that confirm our worldview everywhere and in everything. That’s how we are hardwired. Rigorous adherence to logic and the scientific method is designed to short-circuit a million years of human cognitive (and cultural) evolution in order to more objectively comprehend the universe we inhabit.

        And to further assume that such warming must be human-induced takes the dodgy logic to an even higher level of total befuddlement. Why not go one more step out on the limb and assign blame to your tribe’s traditional enemies for the melting of snow? Oh, wait, I see you already gone there. LOL.

        2. Maybe, maybe not. Analyses of the causes of GW show that we recently emerged from the LIA and that accounts for most of the modern warming trend. Case of experts versus expert that one. Time and further research will tell.

        3. A more nuanced approach to the “warming-causes-increased-and/or-declining-continental-snow-coverage depending-on what-the-weather-is-outside-my-window fallacy. Caused of course by my tribe’s traditional enemies.

        Basically in your mind’s eye everything you see is evidence in support of your hypothesis. Melting snow must be caused by AGW. More snow? Must be AGW!

        I use to argue with Creationists back in the 1980′s and got much the same circular reasoning stream.

        • I’ll refer you to the AR4 WG1 technical summary section on the cryosphere.

          But here’s a quote:

          Snow cover has decreased in most regions, especially in spring. Northern Hemisphere snow cover observed by satellite over the 1966 to 2005 period decreased in every month except November and December, with a stepwise drop of 5% in the annual mean in the late 1980s (see Figure TS.12). In the SH, the few long records or proxies mostly show either decreases or no changes in the past 40 years or more. Northern Hemisphere April snow cover extent is strongly correlated with 40°N to 60°N April temperature, reflecting the feedback between snow and temperature. {4.2}

          and later…

          Since 1978, satellite data have provided continuous coverage of sea ice extent in both polar regions. For the Arctic, average annual sea ice extent has decreased by 2.7 ± 0.6% per decade, while summer sea ice extent has decreased by 7.4 ± 2.4% per decade. The antarctic sea ice extent exhibits no significant trend. Thickness data, especially from submarines, are available but restricted to the central Arctic, where they indicate thinning of approximately 40% between the period 1958 to 1977 and the 1990s. This is likely an overestimate of the thinning over the entire arctic region however.

          As you can see, the timeframe is post 1966 and so it has nothing to do with having ‘emerged from the LIA.’ I know that’s a favorite of the denialist crowd but it’s just not doin it for me, Wes.

          As to the rest of your post, I have to go paint my fingernails so sorry, just can’t get to it. Sigh.

    • Tamino make no such argument. His argument is based on simple statistical analysis of a cherry picked start date.

      I don’t even recall him mentioning AGW in the post in question, just incompetent and/or dishonest statistical analysis.

      • I think Tamino was primarily arguing that Goddard used cherry-picked data and incomplete data and made erroneous claims about the implications of such for AGW.

        Here’s Goddard:

        Canada is normally completely covered with snow in the winter (except for Olympic venues) so the implication is that the US had more snow last week than has been seen in at least the last 44 years.

        Two of the fundamental precepts of global warming theory are that the tropics are supposed to expand, and the Arctic is supposed to warm disproportionately and shrink.

        Tamino pointed out how the data Goddard used was cherry-picked in that he used an incomplete time series and only examined winter months, rather than spring summer and autumn.

        Goddard’s graph sets off some alarms. But they’re not snow-cover alarms, they’re data analysis alarms. For one thing, why only show data for wintertime? Global warming doesn’t mean an end to winter, or to snow. It may even increase snow at certain times and places because warmer air can hold more water vapor. If we look at monthly snow cover anomaly for all months of the year covered by the Rutgers data we see a long-term decline of 37,000 km^2/year, which is statistically significant:

        • Tamino made his point well, perhaps better than he would wish.

          Let’s all agree that continental snow coverage is on a long term decline by 37,000 km2/year minus the margin of error which was about the same size in the 1970′s and with the caveat that the “incomplete” trend flipped to increasing snow cover from 21 years ago, at least in the winter, and is now near an all time high. The long term trend is still for slightly declining snow, but it’s no longer robust evidence for AGW, in fact, Tamino’s expert analysis provides quite the opposite.

          Sure, a biased hack like Goddard can cherrypick trends to diss the contemporary climatological consensus, but it was hardly necessary…Even when the observed data is professionally and honestly handled by Tamino, a high respect researcher in the field it still does not conform to the fundamental predictions of the AGW hypothesis. To paraphrase Sir John, what we need here is a real snow coverage decline catastrophe to confirm the AGW hypothesis — anything less is damaging evidence against the AGW hypothesis regardless of how many times shewonk repeats both declining and increasing snow coverage are evidence for AGW.

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