Stu Ostro – The Weather Channel’s Former Skeptic

December 3, 2010

It’s about that time of year again, as winter snowstorms provoke the inevitable “Whatever happened to Global Warming” jokes and news stories, to be reminded of the powerfully persuasive evidence that made Stu Ostro, senior Meteorologist at the Weather Channel, belatedly wake up to the case for climate change.

I used Stu’s explanation of 2009’s deceptive warmth in one of my most popular videos, which was made to calm the brouhaha after the eastern US was slammed by several extreme snow storms last winter – snow storms that, in fact, were completely consistent with the increased moisture from a warmer climate, coupled with a negative Arctic Oscillation.

5 day composite Temp anomaly - 11/24/10 to 11/28/10

Create your own plot here.

With the UK shivering again from an unusual cold wave, even as some polar areas feel unseasonal warmth, it might be in order to review what happened last year, and remember that just because winters are shorter, and warmer on the whole, we can still get hit with record chills and heavy snows.


17 Responses to “Stu Ostro – The Weather Channel’s Former Skeptic”

  1. danolner Says:

    Sorry for a daft question: that temp anomaly graph, is the baseline an average of 1968-1996 temperatures for the given period, 24th to 28th Nov? Is that what the “composite anomaly” means?

  2. greenman3610 Says:

    I believe that this is composite temperature anomaly – that is – difference in average temp above or below, plus or minus – the average for those days and those areas – using averages from 1968 to 1996 as the base, or zero point.
    That’s the way I read it, anyone else please correct me, if I’m way off I can check with someone who does know.

  3. danolner Says:

    Some other thoughts: so, I’m in York in the UK, near the north-east coast. Current temps here have just reached their lowest this year, about minus 8 celsius, looking at the local weather station –

    Having a quick dig around: wikipedia’s entry on the NAO mentions Europe’s big freeze last year, and includes one suggestion for a factor: solar activity. My wiki-driving isn’t very good; haven’t managed to track down who might have added that, but it’s from Science Daily, citing a Reading researcher. Science Daily also has a link to another theory from the Potsdam institute: “The shrinking of sea-ice in the eastern Arctic causes some regional heating of the lower levels of air — which may lead to strong anomalies in atmospheric airstreams, triggering an overall cooling of the northern continents.” Which fits with the general picture of more warming occurring at higher latitudes, and the disruptive knock-on effects of that. On top of that, there’s the temperature shifts that would occur anyway from NAO variation over time.

    So a question: though one can’t really assign any particular cause, is there a systematic way of analysing the impacts that these various factors might have on a localised anomaly like this? I guess this is part of the general problem of attribution for ‘extreme’ events.

    Annoyingly, I can’t find useful UK snowfall data. There’s this: – and a flick through gives a reasonable sense of ‘days of snow lying’ anomalies that confirm the picture of the last year being a radical break, but it would be nice to be able to access the data itself or see an average anomaly graph for the past fifteen or twenty years. (The data is there but you need a password.) The anecdotal story – as rather amusingly covered by this Independent story from 2000 (“snowfalls are a thing of the past”) is that, until last year, many UK children up to the age of ten had never really seen proper snowfall. This and last winter do seem to be a sudden, radical break from a winter warming trend. But apart from saying “climate change equals climate disruption, so this sort of thing is not unexpected,” is there any more to be said?

    • BlueRock Says:

      Not exactly sure what the question is, but this addresses colder winters in the northern hemisphere as a result of losing Arctic ice:

      – Last winter’s big snowfall and cold temperatures in the eastern United States and Europe were likely caused by loss of Arctic sea ice. In future, cold and snowy winters will be the rule rather than the exception in these regions.

      • greenman3610 Says:

        right, I’m aware of that, and this month’s cold snap in the UK kind of brings it up again, but not everyone buys it.
        I happened upon an answer to this from a senior NASA scientist – responding to this question just the other day:
        “.., in any simulation that has the sea ice changing as a function of increasing GHGs, the impact of GHGs on the NAO/AO(north atlantic oscillation/Arctic oscillation) will dominate (going towards more positive NAO), and that is what is seen in AO timeseries. There is very little evidence (actually none that I’m aware of) of any direct sea-ice/AO link in the observations.

        Even if this were actually the dominant mechanism – to say that this would be well-understood and a well-known predicted consequence of GW would be laughable. It would look much more like a post-hoc scrabble to find supporting evidence for an argument one wanted to make for other reasons. “

        • BlueRock Says:

          So, that’s a direct contradiction of:

          > “The exceptional cold and snowy winter of 2009-2010 in Europe, eastern Asia and eastern North America is connected to unique physical processes in the Arctic,” said James Overland of the NOAA/Pacific Marine Environmental Laboratory in the United States.

          > “In future, cold and snowy winters will be the rule rather than the exception” in these regions, Overland told IPS.

          I’ll drop Prof. Overland an email, see what he says. I’ll let you know.

          • greenman3610 Says:

            I’d be interested.

          • BlueRock Says:

            Reply from Prof. Overland:

            The winter 2009/10 NAO was the most negative in 160 years of record. Negative NAO and AO favor more north south flow than positive values which tend to contain the cold air to the north. This last year had strong weather linakage between the arctic and subarctic weather.

            Warmer temperatures over newly sea ice free areas tend to favor negative AO/NAO weather patterns although other factors such as stratospheric flow and especially just random weather are important. This we do not expect the sea ice effect to be there in every year and in most years it will be more of a local effect. The general relation of a positive AO with GHG has been shown to be a weak effect and does not include the possible sea ice effect from future sea ice loss. Two papers of interest are attached.

            But while the cause is uncertain, winter 2009/10 had an arctic linkage

            And the papers he sent me:


            Email me if you want a copy of PDFs.

          • greenman3610 Says:

            can you go to

            and message me with your email?

    • greenman3610 Says:

      Overall, winters will be shorter and milder – certainly shorter – and we have continued to set many more high temp records than low.
      I’ll be posting Gerald Meehl’s congressional testimony to this effect soon, either separately or as part of a larger vid.

  4. danolner Says:

    Nice post at climate science watch:

    Some good anomaly graphs.

  5. […] Ostro, Weather Channel senior meteorologist. Profiled here last week. Now says, “Skepticism is an important part of the scientific process. It becomes a problem […]

  6. […] Former climate skeptic Stu Ostro is a senior meteorologist at the Weather Channel. In the video above, he explains his transition from skeptic to recognition of the science. […]

  7. […] is a powerful confirmation of something that several fellow meteorologists (including me) have noticed. The weather is doing things it did not do before. Saying that and […]

  8. […] world, rising oceans, and acidifying seas.  Viewers may wish to compare to the similar journey of Weather Channel senior forecaster Stu Ostro. Admiral Titley has appeared in both videos on the National Security aspects of Climate Change, as […]

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