How the Arctic may be impacting UK summers

Monday 17 December 2012, 12:48

Paul Hudson Paul Hudson

We may have to get used to wet summers like we've seen recently across the UK, according Dr Edward Hanna from Sheffield University in an interview which you can see on Inside Out and Look North tonight.

According to Dr Hanna and an international team of scientists, melting summer Arctic ice may be weakening the jet stream, leading it to meander and become slow moving.

This effectively means that weather patterns become locked in for long periods of time.

The jet stream is a ribbon of strong winds high up in the atmosphere, a result of the temperature contrast between northern latitudes towards the Arctic, and latitudes further south.

Because the Arctic is warming faster than any other region on earth, this temperature contrast is getting weaker, leading to a less powerful jet stream in summer.

Crucial to the UK and Northwest Europe is Greenland, a huge mountanous land-mass which can act as a barrier to the jet stream.

If the jet stream is weaker than normal, two things can happen.

It can either split, with one arm going northeastwards, with the other travelling southeastwards towards the UK.

Or the whole jet stream can be deflected southeastwards towards the UK.

The result in both cases would be wet, cool, unsettled conditions as we have seen since 2007.

Not every summer is likely to be poor.

The slow-moving jet stream may become positioned to the north of us, leading to warm settled conditions.

But because of our position relative to Greenland, these summers are likely to be the exception to the rule.

Dr Hanna says if this theory is correct and summer Arctic ice melt continues, there is also likely to be a higher risk of extreme rainfall events such as we have experienced in 2007 and again this year.

The research, which was carried out jointly by experts from NOAA (National Oceanic and Atmospheric Administration), Rutgers University, University of Washington, and the University of Sheffield, was published in the journal Geophysical Research Letters.

You can see more on this on BBC Look North from Leeds, on BBC1 at 6.30pm, (Sky channel 956, Freesat 966) or on BBC1's Inside Out at 7.30pm (Sky 956 & 957, Freesat 966 & 967).

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  • rate this
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    Comment number 81.

    Lateintheday

    "F&R also assume that outside of their very selective short term 'forcings', earths climate is essentially stable."

    Roy Spencer picks up on this theme at his blog

    http://www.drroyspencer.com where he says

    "Over the last quarter century, mainstream climate science has changed dramatically, from a paradigm where climate changes naturally to one where climate forever remains the same unless humans meddle with it"

  • rate this
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    Comment number 82.

    71. greensand wrote:

    "... I doubt that the location will meet with DW's approval..."

    Let's just say that if Willis Eschenbach feels he has something meaningful to add to the scientific literate, such as a reviewed rebuttal to Levitus et al., then nothing is preventing him from doing so.

  • rate this
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    Comment number 83.

    72. lateintheday wrote:

    "What I see newdwr54 is that there were 10 solar peaks in the 20thC and six of the last seven were higher than the first three. According to you (and climate science consensus) those first three were strong enough to cause warming and yet for some inexplicable reason, the later six cycles (which were clearly higher peaks) cannot cause warming. That's ridiculous."
    _______________________________

    All I've said on this is that since the 1950s the solar influence has been in decline. That's clear from the data, whether you use sunspot numbers or TSI. Over this period of solar decline, global surface temperatures and (more significantly) ocean heat content have increased. So it's straightforward as far as I can see; something other than solar variation has caused the planet to warm up.

    "As for the one lower cycle of those latter seven - that would be around the time when temps flattened would it not? Around the time we were told the next ice age was on the way. And this current flat 15 year trend seems to have coincided with half a low solar cycle also."
    ____________________________

    Eye-balling that Wiki chart, I would say that solar influence peaked around 1955 and has declined since. Would you agree? The low cycle was around the early 1970s?

    "Your point that cycles since the 80's have been trending down is simply irrelevant. Those cycles show higher peaks than those which have already been acknowledged to cause warming."
    ___________________________

    No, because the theory is that reduced solar output causes greater GCRs in the atmosphere. This (it is said) means more clouds, less insolation, and therefore "cooling".

    But we haven't seen any cooling LitD. That's the problem with GCR theory.

  • rate this
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    Comment number 84.

    #71. - greensand wrote:
    "Given past reactions I doubt that the location will meet with DW's approval but that does not make the comments/questions any less pertinent."

    Thanks for posting that, it's interesting to read the comments, but I haven't been able to get through them all yet.

  • rate this
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    Comment number 85.

    82. newdwr54 wrote:

    "Let's just say that if Willis Eschenbach feels he has something meaningful to add to the scientific literate, such as a reviewed rebuttal to Levitus et al., then nothing is preventing him from doing so."

    Usual MO DW, nothing to say about the actual subject.

  • rate this
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    Comment number 86.

    84. QuaesoVeritas wrote:

    "Thanks for posting that, it's interesting to read the comments, but I haven't been able to get through them all yet."

    Glad you found it of interest.

  • rate this
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    Comment number 87.

    85. greensand:

    I don't have that much time GS. As I'm sure you don't.

    If the man's arguments are so compelling then, if I were you, I'd be wondering why he doesn't submit them to peer review.

    Why do these unnaturally enlightened folk not submit their evidence and arguments to people who actually know what they're talking about?

    Why do they always and only publish them on weblogs and to sympathetic audiences?

    If I were you, I'd be much more concerned about those questions.

  • rate this
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    Comment number 88.

    87. newdwr54 wrote:

    "If I were you, I'd be much more concerned about those questions."

    Well, no DW, I am not.

    Not all in peer review is correct, not all rebuttals are correct, not all blogs posts/comments are wrong. I take everything I read on merit not reputation. A lot of what I read I do not have the ability to comprehend, so I do not comment. Hence I try very hard to confine my involvement to the actually observational data.

    If you are saying that because you are short of time you are willing to let the peer reviewed literature formulate your conviction then so be it, your choice to be led by authority. But to "champion" a cause on such a brief is also beyond my comprehension.

    The meme that only articles in the scientific literature warrant consideration is illogical, indicative of restrictive practices and tantamount to censorship.

  • rate this
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    Comment number 89.

    QV

    You and others may also find the comments interesting from here:
    http://tallbloke.wordpress.com/2012/02/27/argo-the-mystery-of-global-warmings-missing-heat/

  • rate this
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    Comment number 90.

    Sorry chaps, but where are you getting your TSI information from?

    When I look at the data, I do not see a decline from the 50's, you might be able to get a declining trend by picking the peak(1365.97) before the last peak(1366.08), but with the best will in the world its not really been in decline, that's just cherry picking, especially as the most recent peak was higher, if only by a little.

    A lot of other solar indicators are in decline, but I dont think that you could count TSI as one of them. Are you working from Hoyt perhaps?

  • rate this
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    Comment number 91.

    oops, should have finished that thought.... Hoyt, spliced with another dataset?

  • rate this
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    Comment number 92.

    Ah...Ha.... Leif 2007 maybe?

  • rate this
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    Comment number 93.

    88. greensand:

    An argument from authority is only a fallacy if the source does not possess legitimate expertise or does not represent the consensus of expert opinion.

    You can go around the internet and pick up posts from people who tell you, on their own reckoning, that the world is considerably less than 10,000 years old. Or you can find people who will tell you, on their own reckoning, that the oceans aren't really gaining heat.

  • rate this
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    Comment number 94.

  • rate this
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    Comment number 95.

    93. newdwr54 wrote:

    “An argument from authority is only a fallacy if the source does not possess legitimate expertise or does not represent the consensus of expert opinion.”

    Or if the recipient does not possess the intellect to disseminate the flaws within the “consensus of expert opinion”. Example mid 20th Century European history

    “You can go around the internet and pick up posts from people who tell you, on their own reckoning, that the world is considerably less than 10,000 years old. Or you can find people who wil

    And that is when you use your brain and intellect to disseminate the information into comprehensible partitions. Make your decisions, based on your own understanding.

    Spin it, as you usually do, but your position is and always has been an argument from authority. That is why you feel the need to decry every single, even minor issue that might not meet the AGW play sheet. Tis not possible for one homo sapien, but maybe for the new homo superbus?

  • rate this
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    Comment number 96.

    94. ukpahonta wrote:

    And that is an excellent illustration of why we should celebrate the ability to access the real, none sanitised, world of climate science. How it will turn out I know not, but I do know, if I keep my mind open I will have the opportunity to learn

  • rate this
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    Comment number 97.

    Still no HadSST2/3 let alone HadCRUT3/4 for November.
    Last year they were published by the 14th and 20th.
    I wonder if everyone at the MO has started their Christmas holidays?

  • rate this
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    Comment number 98.

    On the other hand, maybe they are all preparing for the end of the world tomorrow!

  • rate this
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    Comment number 99.

    @ukpahonta #94

    Excellent, those are exactly the points I've been trying to make. The normal excuses for explaining the current lack of warmth Areosols etc. Are now shown to be invalid, so the estimates of sensitivity especially the highers ones 3+ degrees and over are now looking to be untenable - The models, no matter how you slice it, are most definitely running too hot and where is the Heat? Should be our most often asked question. It's not hidden, it's simply not present.

    This show is finally starting to come to an end and I think we should all be thankful for that - Science will, in the end, win out and our more alarmist comrades will eventually have to come back into the fold.

    I hope the rhetoric and the politics will also calm down, but as that's mostly driven by activists, we may have to wait a while longer for that.

    Deniers, if that's what we are can all be proud that we stood against these people and science and it's practice can start to getting back to normal.............

    Reasonable people on all sides eventually have to face facts

  • rate this
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    Comment number 100.

    # 99

    Take the science, maths and stats aside for a moment.

    The whole issue of GW has been a bumper bonanza to politicians the world over incapable of managing but quite capable of over-spending copious funds from taxed-out folk. As long as the political wing of society has a hook to gather more revenue with apparent ease we can all rest - assured that all will be well !

    If everything returns to normal where will the next gravy train come from ?

 

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Hello, I’m Paul Hudson, weather presenter and climate correspondent for BBC Look North in Yorkshire and Lincolnshire. 

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I worked as a forecaster with the Met Office for nearly 15 years locally and at the international unit, after graduating with first class honours in Geophysics and Planetary physics at the University of Newcastle upon Tyne in 1992. I then joined the BBC in October 2007, where I divide my time between forecasting and reporting on stories about climate change and its implications for people's everyday lives.

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