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Storm Desmond rainfall partly due to climate change, scientists conclude


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Posted
  • Location: Camborne
  • Location: Camborne
Quote

Manmade climate change was partly responsible for Storm Desmond’s torrential rain which devastated parts of Scotland, the Lake District and Northern Ireland, scientists have concluded.

The researchers at Oxford University and the Royal Netherlands Meteorological Institute (KNMI) calculated that climate change had made the flooding event 40% more likely, with the estimate of the increased likelihood ranging between 5% and 80%.

:hi:

http://www.theguardian.com/environment/2015/dec/11/storm-desmond-rainfall-flooding-partly-due-to-climate-change-scientists-conclude?CMP=share_btn_tw#comments

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Posted
  • Location: London, England
  • Weather Preferences: warm summers, cold winters
  • Location: London, England

I'm not sure one storm proves or disproves anything. We have many factors strong jet stream, strong El Nino, strong polar vortex, high pressure pulling in moisture from Florida. So lots of contributions. Climate change could play a part but I don't think one storm proves anything.

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Posted
  • Location: Witney west oxfordshire
  • Location: Witney west oxfordshire
2 hours ago, ColdFront80 said:

I'm not sure one storm proves or disproves anything. We have many factors strong jet stream, strong El Nino, strong polar vortex, high pressure pulling in moisture from Florida. So lots of contributions. Climate change could play a part but I don't think one storm proves anything.

what they mean is that the probability of an event of this magnitude was made that much more likely because of climate change. They start from climate change being accepted as fact rather than using this event to try to 'prove' climate change, which as you say, as a single data point be pretty hopeless.

So, I think they say, which is in line with concensus is, that these storms have always happened, it is just that bit more likely that we get a storm with rainfall over x amount than it would have been prior to climate change. 

Edited by mud_error
hadn't finished
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Posted
  • Location: North York Moors
  • Location: North York Moors
30 minutes ago, mud_error said:

what they mean is that the probability of an event of this magnitude was made that much more likely because of climate change. They start from climate change being accepted as fact rather than using this event to try to 'prove' climate change, which as you say, as a single data point be pretty hopeless.

So, I think they say, which is in line with concensus is, that these storms have always happened, it is just that bit more likely that we get a storm with rainfall over x amount than it would have been prior to climate change. 

Meaningless phrase being bandied about.
What actual mechanism is being proposed - the North Atlantic is cooler not warmer, so not sure how warmer is supposed to be making heavier rain.
Same is true of the +0.7C over 150 years - that doesn't enable the atmosphere to hold inches more rain.
In short it's a noteworthy weather event and the Lake District gets a lot of weather.

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Posted
  • Location: North York Moors
  • Location: North York Moors

BTW has the record rain total even been accepted officially yet?
I have seen some comment that only the Honister gauge recorded substantially more than the traditional wet spots nearby like Seathwaite Tarn.
It isn't a standard rain gauge but uses tip buckets.
These are known to over-record when it's very windy which it certainly was at that exposed location.

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Posted
  • Location: halifax 125m
  • Weather Preferences: extremes the unusual and interesting facts
  • Location: halifax 125m

Personally I think that climate change will only be proven as time goes on.It is a little meaningless wether or not Honister has taken seathwaites record as they are only a stones throw apart and no one can deny the scale of rainfall that has fallen. I do however and just how it feels to me over the years with no scientific basis see many occasions in the last few years when we seem to get the phrase 'the Jetstream is stuck' and we see endless forcasts of atlantic fronts lined up one after the other.It just seems much more often to me that this seems to happen.With rainfall records in this area in 2007 and 2012 accompanied with the northwest in 2005 and now and the thames floods just a few years ago it does make you think is there something different happening?

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire

I've never understood why some folks get so defensive when climate change is referenced as a potential influence for a weather event. I mean, there's virtually no doubt that it's happening, so why wouldn't it have some impact?

Edited by Nick L
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Posted
  • Location: Morecambe
  • Location: Morecambe
12 hours ago, Nick L said:

I've never understood why some folks get so defensive when climate change is referenced as a potential influence for a weather event. I mean, there's virtually no doubt that it's happening, so why wouldn't it have some impact?

That is true but what we don't want is for any mis quotes to take place and for this event to be purely down to climate change where this kind of flooding has occured well in the past before and natural factors have played there part(e.g, warm moist air hitting western hills creating persistent heavy rainfall).

I also wonder if part of the reason why we see more records being broken nowadays(be it any type of weather) could be down to the lack of weather stations/technology way back many many years ago. Who to say we havant had more rain fallen in a period of time way back hundreds of years ago but there was no weather station to report that?

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Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary
15 hours ago, 4wd said:

Meaningless phrase being bandied about.
What actual mechanism is being proposed - the North Atlantic is cooler not warmer, so not sure how warmer is supposed to be making heavier rain.
Same is true of the +0.7C over 150 years - that doesn't enable the atmosphere to hold inches more rain.
In short it's a noteworthy weather event and the Lake District gets a lot of weather.

Yes, there is a cold pool to our west and northwest, but the air for this rainfall event came from the southwest where there are much more warm anomalies than cold anomalies. Overall, the north Atlantic is still much warmer than average.

Also, this doesn't have to be yet another record rainfall event. What the scientists said were about the probability of these event happening. Besides, the record high river levels in some places, as well as records in Ireland and other locations, also indicate that this was an extreme event, regardless of the type of rain guage used.

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Posted
  • Location: Powys Mid Wales borders.
  • Location: Powys Mid Wales borders.

The climate is always changing, the phrase climate change is a misnomer.

There are many other factors that are causing this warming causing more intense rainfalls,that I do agree it is warming slowly which will also cause the jet to be stronger.

Theres nothing there can do about it.

Mother nature will do as she please`s.

Edited by Snowyowl9
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Posted
  • Location: Camborne
  • Location: Camborne

Although Britain is not getting any rainier overall, Met Office data show that “intense” rainfall days are one-third more common than 50 years ago. There is a “reasonable amount of confidence” among climate scientists that heavier storms in Britain may be linked to rising sea temperatures and changing winds in the north Atlantic, says Jim Hall, director of the Environmental Change Institute at Oxford University.

This has increased the risk of the sort of surface-water flooding seen after Storm Desmond. Whereas prolonged, moderate rainfall makes rivers spill into floodplains, intense rainstorms cause even places on high ground to flood when the capacity of drains is exceeded. According to the Environment Agency, 3.8m properties in England are at risk from surface-water flows, compared with 2.4m from rivers and the sea. Insurance claims for damage caused by such floods make up 60% of flood-related claims and rising, according to Matt Cullen of the Association of British Insurers.

That is not surprising, given that surface-water drains in Britain are built to deal with, at most, a once-in-30-years rainfall, calculated on figures not updated since the 1990s. And with local authorities and sewerage firms’ budgets squeezed, many drains suffer blockages and overflow even during moderate downpours. Spending on flood defences has been topped up since high waters in Somerset threatened to spill into political crisis last year. But most of the new money has gone towards dealing with tidal surges and river flooding, rather than inadequate drainage. Even the £4.2 billion ($6.3 billion) Thames Tideway “super sewer” project, which will get under way in the capital next year, will not be able to cope if intense-rainfall forecasts continue to be revised upwards.

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Posted
  • Location: Camborne
  • Location: Camborne

Research over the last decade has shown that the majority of heavy precipitation and flood events on the western edges of mid-latitude land masses are connected to intense water vapor transport. This vapor transport is found within the atmospheric river region of extratropical cyclones. As climate change is expected to create a warmer atmosphere capable of supporting more water vapor, it is also thought that the global water cycle will intensify leading to more vapor flux and hydrological extremes, such as floods and droughts. Any changes to the water vapor transport by the atmosphere are likely to have hydrological ramifications of great significance to hydrometeorological applications.
The research presented in Lavers et al. (2015) investigates the historical and projected changes to water vapor transport in the latest Climate Model Intercomparison Project Phase 5 archive. Using output from 22 models, robust increases in vapor flux by the end of the 21st Century are found, which suggests the likelihood for larger precipitation and floods in the future. This research was a collaborative effort led by CW3E, with the aim of ascertaining the projected global water cycle changes that may need to be considered in the future.

Abstract of Lavers et al. (2015)*: Global warming of the Earth’s atmosphere is hypothesized to lead to an intensification of the global water cycle. To determine associated hydrological changes, most previous research has used precipitation. This study, however, investigates projected changes to global atmospheric water vapor transport (integrated vapor transport (IVT)), the key link between water source and sink regions. Using 22 global circulation models from the Climate Model Intercomparison Project Phase 5, we evaluate, globally, the mean, standard deviation, and the 95th percentiles of IVT from the historical simulations (1979–2005) and two emissions scenarios (2073–2099). Considering the more extreme emissions, multimodel mean IVT increases by 30–40% in the North Pacific and North Atlantic storm tracks and in the equatorial Pacific Ocean trade winds. An acceleration of the high-latitude IVT is also shown. Analysis of low-altitude moisture and winds suggests that these changes are mainly due to higher atmospheric water vapor content.

*Lavers, D.A., F.M. Ralph, D.E. Waliser, A. Gershunov, and M.D. Dettinger, 2015: Climate change intensification of horizontal water vapor transport in CMIP5. Geophys. Res. Lett., 42, doi:10.1002/2015GL064672.

http://woodland.ucsd.edu/?cat=12

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Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft

I see storm Eva has now been put down to 'climate change'. 

So there you go its a done deal 

Funny the violent storm of 28 dec 1879 was not put down to climate change, that one killed 56+ people.

https://en.wikipedia.org/wiki/Tay_Bridge_disaster

 

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