Barrage over climate change link to floods

 
Flooding

As the barrage of bad weather eases, another kind of turbulence is brewing over one of the potential causes.

Listen to some environmental campaigners and you might think that there is total certainty that global warming led to the recent rain; listen to some climate sceptics and there is absolutely no connection at all.

Viewers have berated me either for failing to explicitly blame climate change in my reporting of the floods - or for suggesting that the rain may conceivably have been made more likely by the rising presence of manmade greenhouse gases.

For anyone coping with clearing up a flooded home, this question will not exactly be the highest priority.

However, political figures have raised its profile, making the connection rather more forcefully than many scientists.

The Prime Minister, David Cameron, set the tone by telling the Commons that he "very much" suspects that climate change is involved. And the Labour leader, Ed Miliband, warned that "we are sleepwalking into a national security crisis on climate change".

Of course not every politician agrees. Lord Lawson, on the Today programme, dismissed any link to the weather, saying, "the question is whether global warming has marginally exacerbated it. Nobody knows that".

Different takes

If we stand back from the Westminster hothouse, what do the scientists actually say?

The fact is that attributing a human influence to individual weather events is an emerging area of research and is acknowledged by those involved to be extremely challenging because so many factors are at work.

One leading figure in climate science, Professor Sir Brian Hoskins, summed it up bluntly: "There's no simple link - we can't say 'yes' or 'no' this is climate change."

Instead, he and others point to a range of factors which would make intense downpours more likely.

The key one is a basic physical relationship: since warmer air can hold more moisture, it makes sense that our warming atmosphere would produce more intense rain.

But how much rain? And where? The computer models used to explore scenarios for the impacts of different levels of greenhouse gases are recognised to be weaker on rainfall than on temperature.

Surely, you might think, the UN's Intergovernmental Panel on Climate Change (IPCC), the consensus assessment of the latest science, might clear this up? As so often, you can read its documents in different ways.

If you think global warming is overplayed, you focus on this conclusion in the most recent IPCC report:

"There continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale."

Translated, that means we're not seeing more floods, story over.

However, if you do think climate change is serious, your eye may fall, first, on the line that "the frequency or intensity of heavy precipitation events has likely increased in North America and Europe."

Second, the IPCC predicts that "extreme precipitation events" over the mid-latitudes (which includes Europe) will very likely become more intense and more frequent. Doesn't this explain the recent British weather? Is this the smoking gun? No, because this scenario will unfold "by the end of this century" rather than right now.

Looking for answers

Another take comes in a report by the European Academies Science Advisory Council published in November last year.

It suggests a future in northern Europe in which "high intensity and extreme precipitation become more frequent…" and that "future projections suggest increases in flood risk over a wide area of Europe…"

So bad news on the way, clearly, but none of this categorically nails the question we began with - exactly how much manmade greenhouse gases are involved in the current weather.

A study by the Met Office and Centre for Ecology and Hydrology concluded that "it is not possible, yet, to give a definitive answer on whether climate change has been a contributor or not."

Their report points to the sea level rising and an increase in storminess in the North Atlantic as factors consistent with climate change. But it also highlights what is not properly understood, including the path of the jet stream, which has acted as a conveyor belt, delivering storm after storm.

At the launch of the report, the Met Office chief scientist, Dame Julia Slingo, seemed to go a bit beyond what appeared in print.

She said: "All the evidence suggests there is a link to climate change." Not some of the evidence, but all of it.

So what about that unexplained path of the jet stream? The Mail on Sunday quoted one Met Office scientist, Professor Mat Collins, as saying that "there is no evidence that global warming can cause the jet stream to get stuck in the way it has this winter."

The Met Office scrambled to produce a statement to assert that there was no disagreement. It also confirmed the "uncertainty" about the storm track in the North Atlantic but did not address whether the chief scientist had gone beyond the conclusions of their own report.

Does this leave us any wiser? No. In my experience scientists always disagree - that's how research advances.

Dr Tim Osborn of the University of East Anglia is among climate researchers concerned about the science of extreme weather being portrayed as a little more certain than it might appear.

"You've got a lot of natural variability superimposed on the long term trend - in the next 20 years, the frequency of weather like this winter's could drop below the trend or rise above it. We're not expecting a year on year change."

The only way to detect a human fingerprint on weather is to run simulations of the event as it actually happened - and then to repeat them having stripped out the greenhouse gas component in the models.

Previous studies of this kind, for example into the 2000 floods in England, have found that the storms were made more likely because of manmade climate change - likely but not certain.

The answer is framed as an increased probability. A categoric answer may never be possible.

As the country copes with the floods and starts repairs and thinks about making things safer for the next one, people will look up at the skies and want certainty about whether wild winters will become normal. And at the moment, the science cannot provide that.

 
David Shukman Article written by David Shukman David Shukman Science editor

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  • rate this
    +1

    Comment number 821.

    #805
    "Tell me. Are weather forecast models 'validated'? No? In which case, why do you watch the weather forecast?"

    I don't! That's the worst hocus-pocus of it all - promulgated by the man-made climate change gurus at that horrendous quango the Met. Office.

  • rate this
    0

    Comment number 820.

    Just heard the report on RT news about the fracking well that EXPLODED causing massive damage in USA...when all these wells go up across our countryside, will theyhelp our farmland drain or destroy homes, farms villages and towns instead??

  • rate this
    0

    Comment number 819.

    811.John
    They've got to stop following EU dictate and dredge & dispose the dredgings as they've done in the past cheaply by spreading on the land
    Wasn't it EU loving Labours Baroness Young who said she would like to attach limpet mines to all the pumps in the levels when she was in charge
    Maybe we could send her an Invoice for all the damage !

  • rate this
    +1

    Comment number 818.

    815.Welsh Dragon
    Are you talking about pollution or CO2 when you use Beijing as a comparison ?
    Local polluting of air quality in cities of particulates etc is a real problem but the effects of minuscule CO2 gas goes which is the new tax Govts have been looking for has got to be the biggest deception of the 20th cent

    https://twitter.com/CoachesHotSeat/status/434231021316218881/photo/1/large

  • rate this
    0

    Comment number 817.

  • rate this
    +1

    Comment number 816.

    814. jauntycyclist

    "812
    I think u lost in some deep darkness"

    It's far simpler. I'm just brighter than you. Feel free to prove me wrong by correcting your flawed arguments and inconsistencies as clearly laid out in 812. But somehow, I don't think that's going to happen.

    Not unless you're able to magic up a maths/science/engineering degree (which you clearly don't have) in the next few minutes!

  • rate this
    +2

    Comment number 815.

    All I know is there is some very curious thinking out there. Beijing has to take traffic reduction measures because a few million humans have changed the atmosphere over 10 years. Think Olympics 2008.

    But there are those that believe billions have had zero effect on the atmosphere these past hundreds of years and will have zero effect in the countless millennia to come.

    Strange. Very strange.

  • rate this
    +2

    Comment number 814.

    812
    i think u lost in some deep darkness
    look at the ippc validation reports how uncertain they are.

    those hallucinating about a co2 deathstar cannot have it both ways. they cannot rely on unvalidated models and the predictions that come out of them then call anyone who doesn't obey without question a 'science denier'.

  • rate this
    0

    Comment number 813.

    Those looking for proof would do well to look for proof that emissions are safe. Consider Pascal's Wager. Either the climate is changing because of us or not. Either we act or not. Given the 4 possible combinations, action makes sense. Given the probabilities, even more so.

  • rate this
    -2

    Comment number 812.

    @810. jauntycyclist
    "I will be generous."
    Is THAT validation??? What 'you' define!!!

    "If the climate models can predict with 80%"
    Probability - told you! Now YOU'RE 'betting' as you put it. Why not 75% or 85%??? Who decides?

    And once the threshold is 'decided', is it 'truth' or a question of belief by others?

    See the flaws (and inconsistencies) in your reasoning now?

  • rate this
    +1

    Comment number 811.

    The eco-friendly solution to flooding is to only defend towns and to let flood plains and rural areas flood.
    The Somerset Levels have already suffered as a result, in part, of this policy. This leaves three choices for DEFRA:
    Deny global warming and do nothing
    Build flood defences and destroy various habitats.
    Admit that communities are to be sacrificed
    It will be interesting to see what they do.

  • rate this
    0

    Comment number 810.

    809

    i will be generous. if the climate models can predict with 80% to the observed then lets look at it. but its no where near

    there is nothing wrong with having unvalidated models It only becomes a prblem if u start basing predictions on them and then demand action be taken on them then calling anyone who disagrees a 'science denier' and say anyone in public office who does not obey be purged

  • rate this
    0

    Comment number 809.

    @807. jauntycyclist
    "without validation its belief. if its probabilities its just betting."

    Define 'validation'. I defy you to do it without reference to probability.

  • rate this
    0

    Comment number 808.

    @806
    Forget complex planetary phenomena, there isn't even a 'perfect' model for measuring the 'true' length of a table!

  • rate this
    0

    Comment number 807.

    805 lol

    without validation its belief. if its probabilities its just betting. if the weather models could predict with a statistical edge then they would be making a fortune at the bookies. But they don't.

    the models are not validated which is why the predictions are 97% wrong. Meto forecast drier than normal winter.

    all i see is eco utopians hallucinating there is a co2 deathstar

  • rate this
    0

    Comment number 806.

    jauntycyclist @804
    "validation"

    Will there ever be a perfect 'model', of an infinitely complex planetary reality?

    It is right to want more research, 'proof' of serviceability as much as reasonably possible, but bear in mind the incompleteness of our 'understanding' even of the past (recorded under Queen Victoria, or surmised from study of rocks) from which we derive and against which we 'test'.

  • rate this
    -1

    Comment number 805.

    802. jauntycyclist

    Tell me. Are weather forecast models 'validated'? No? In which case, why do you watch the weather forecast?

    On/off. Good/bad. Right/wrong. Validated/unvalidated.

    False argument.

    Think statistics and probabilities - the basis of science. Next you'll be claiming Satnav GPS co-ordinates are 'unvalidated'.

  • rate this
    +1

    Comment number 804.

    801

    i did post a link a while back on the ippc validation report [its a pdf and an audio. at the end they mumble some of the caveats. there are even worse problems with the models when it comes down to the regional and away from global averages which hide a lot of sins

    basically unless climate models can replicate past known climate [which they cannot- bust TV] how can they predict the future?

  • rate this
    -1

    Comment number 803.

    796. LUFC_FR
    "Worth a read if you're on the fence regarding the daily drivel of 'damage caused by Global warming': http://nipccreport.com/

    These guys KNOW what they're talking about."

    ---
    Assuming quoting Chinese-funded research, is 'knowing what you're talking about'. That'll be the same China whose energy demands require an argument in favour of disgorging more CO2 into the atmos.?

    Busted.

  • rate this
    +3

    Comment number 802.

    800

    ?

    u claiming predictions from unvalidated models should be the basis of policy and taxation?

    even the ipcc say their models are not validated.

    tell u what lets forget proving things with verified models lets just dismantle society paint ourselves in blue woad and live in eco anarchist utopia.

 

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