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CraigsIsland

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Met Office (UK) "suggests climate change link" on recent storms
« on: February 12, 2014, 01:41:48 AM »
Found a BBC article that was quite interesting:

http://www.bbc.co.uk/news/uk-politics-26084625

and further looked at the accompanying report released by the Met Office:

http://www.metoffice.gov.uk/media/pdf/1/2/Recent_Storms_Briefing_Final_SLR_20140211.pdf

Lots of useful information if you're curious about these events

ChrisReynolds

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #1 on: February 12, 2014, 09:51:45 PM »
A hydrologist on BBC News 24 earlier (sorry didn't get the name) was describing how he was involved in a study into UK measures to adapt to climate change, in particular flooding. He said that the sort of event we're experiencing is the sort of event the IPCC models lead them to believe would be expected after the 2030s.

I've seen storms as bad as this, but never one after another. The Met Office report makes a good case of a role for AGW (warm SST in Indonesia, and the Atlantic, increased rainfall with increased temperature).

ChrisReynolds

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #2 on: February 16, 2014, 08:46:29 PM »
I am now more convinced than ever that the UK flooding disasters of 2007 and 2012, and the extreme wet summers of 2007, 2008, 2009, and 2012 were caused by the loss of sea ice.

I've calculated that there is a 99.8% probability that 2007,2008,2009 and 2012 being in the top ten wettest years in the UK is not by chance. i.e. only 0.14% probability they are just random occurences.

As I've just posted on my blog:

Quote
The likelihood of finding that four of the top ten wettest years in the UK lie between 2007 and 2013 by random chance is 0.14%. Therefore it is a virtual certainty (99.8% probability) that  the occurrence of 2007, 2008, 2009 and 2012 in the top ten wettest years in the UK is not by chance, but is due to a shift in the processes at play in delivering rainfall to the UK....

Therefore the UK is experiencing cooler wetter summers, likely as a result of sea ice loss. And this has lead to damaging flooding events in 2007, and 2012. This is not happening by chance, it is climate change, ongoing and causing damaging consequences to lives, property and agriculture.


More at my blog.
http://dosbat.blogspot.co.uk/2014/02/uk-wet-summers-post-2007-how-unusual.html

wili

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #3 on: February 16, 2014, 09:03:30 PM »
CR wrote:

Quote
I am now more convinced than ever that the UK flooding disasters of 2007 and 2012, and the extreme wet summers of 2007, 2008, 2009, and 2012 were caused by the loss of sea ice.

I've calculated that there is a 99.8% probability that 2007,2008,2009 and 2012 being in the top ten wettest years in the UK is not by chance. i.e. only 0.14% probability they are just random occurences.

Coming from the guy who correctly predicted the extent of end-of-season melt last year, that is something to take quite seriously. I hope you don't mind if I post this elsewhere (properly attributed, of course).
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

ChrisReynolds

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #4 on: February 16, 2014, 09:26:32 PM »
Feel free. I'm more sure of the result than if I'd done it by algebra (maths not great) - still not sure I needed to use a monte-carlo approach. But the probability is basically worked out by randomly shuffling the data and seeing how many times I get four years (between 2007 and 2013) in the top ten for a million shuffled datasets. I suspected the answer was low - but that low (0.14% probability it's random)


Don't read the sea ice prediction thing into this though, just because someone's right on one thing doesn't mean they are on everything.

wili

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #5 on: February 17, 2014, 02:59:36 AM »
"Don't read the sea ice prediction thing into this though, just because someone's right on one thing doesn't mean they are on everything."

Maybe your mantel will eventually fall, but for now, you are the big enchilada, the big kahuna, the BSD...enjoy it while you may.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

ChrisReynolds

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #6 on: February 17, 2014, 07:53:17 AM »
Over at Neven's blog DCS has produced the equation to work out the probabilities by algebra, it agrees with my amateurish method of calculating the probability.

Quote
Chris:

Using a hypergeometric distribution gives about the same result:

(7! /(4! 3!) (97! / (6! 91!)) / (104! / (10! 94!)) = about 0.001325

I'd rather calculate the probability of four or more (instead of exactly four) of the top ten years being after 2006, which is about 0.001378.

So that's a 99.8622% probability that the four years in the top ten is not due to random chance. I'll stick to rounding down to 99.8%.

Jim Hunt

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #7 on: February 18, 2014, 11:10:42 AM »
The Met Office's video summary of UK weather throughout January:




Quote
For the South of England it was the wettest January on record, and also the wettest January in the long running England and Wales precipitation series, that extends back to 1766.
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

Jim Hunt

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #8 on: February 21, 2014, 02:30:44 PM »
The Met Office's latest update states that:

Quote
This has been the UK’s wettest winter on record in the national series going back to 1910. With just over a week to go until the end of the season the UK has now received 486.8mm of rain, narrowly above the previous record of 485.1mm set in 1995.

Meanwhile in the Grauniad George Monbiot explains "How we ended up paying farmers to flood our homes"

Quote
Along the road from High Ham to Burrowbridge, which skirts Lake Paterson (formerly known as the Somerset Levels), you can see field after field of harvested maize. In some places the crop lines run straight down the hill and into the water. When it rains, the water and soil flash off into the lake. Seldom are cause and effect so visible.

Here's my version of his image of the soil of South West England being washed out to sea, courtesy of NASA WorldView. If you switch to 7-2-1 it's easy to see "Lake Paterson".

« Last Edit: February 22, 2014, 01:28:29 AM by Jim Hunt »
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #9 on: February 21, 2014, 05:13:42 PM »
The Met Office's latest update states that:

Quote
This has been the UK’s wettest winter on record in the national series going back to 1910. With just over a week to go until the end of the season the UK has now received 486.8mm of rain, narrowly above the previous record of 485.1mm set in 1995.

Meanwhile in the Grauniad George Monbiot explains "How we ended up paying farmers to flood our homes"

Quote
Along the road from High Ham to Burrowbridge, which skirts Lake Paterson (formerly known as the Somerset Levels), you can see field after field of harvested maize. In some places the crop lines run straight down the hill and into the water. When it rains, the water and soil flash off into the lake. Seldom are cause and effect so visible.

Here's my version of his image of the soil of South West England being washed out to sea, courtesy of NASA WorldView. If you switch to 7-2-1 it's easy to see "Lake Paterson".


How stupid can you be? Contour plowing should be standard practice by all farmers. This  has the effect of preserving topsoil and increasing yields, long term.

ChrisReynolds

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #10 on: February 21, 2014, 09:47:42 PM »
Thanks Jim.

Jim Hunt

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #11 on: February 22, 2014, 01:44:55 PM »
My pleasure Chris. Here's the BBC's take on the "wettest winter on record" story:

http://www.bbc.co.uk/weather/feeds/26295801

Quote
Huge amounts of rain courtesy of a remarkably intense jet stream which has been powering across the Atlantic all winter long.

Apparently some ski lifts in the Western Highlands of Scotland have been buried under 4.5 metres of snow as a result of all this precipitation! Perhaps Glencoe should put in a bid for the next Winter Olympics? It seems Sochi currently has less than 3 metres on the upper slopes:

http://www.bbc.co.uk/weather/features/26289140

Whilst our glorious government ponders that question, the Met Office has issued yet another severe weather warning, this time for the Highlands amongst other places:

"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

bligh8

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #12 on: February 23, 2014, 07:13:34 AM »
Jim,

What happened in England was Horrible, rain not seen in nearly 250 yrs. And indeed all over the Northern Hemisphere there were temperatures and conditions not seen before  in modern history. From Ice storms in Georgia US, to warmer weather in Alaska.
There has been some contentious debate about the role of Arctic Sea Loss and the meandering jet stream in relation to these events. How could we think that the loss of so much ice would not have a profound effect on the climate?

Best,
Bligh

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #13 on: February 23, 2014, 03:52:02 PM »
What happened in England was Horrible, rain not seen in nearly 250 yrs. And indeed all over the Northern Hemisphere there were temperatures and conditions not seen before  in modern history. From Ice storms in Georgia US, to warmer weather in Alaska.
There has been some contentious debate about the role of Arctic Sea Loss and the meandering jet stream in relation to these events. How could we think that the loss of so much ice would not have a profound effect on the climate?

Can I suggest we need to start being careful with how we say things? (and the media fails very much as is shown by the 250 year thing).

Are we saying that 250 years ago there was actually more rain? Or are we saying that the current rainfall is unprecedented within the historical record? (which is a very different thing)

Anyway I for one am rather glad to see climate change impacts hitting the UK and US - two nations with massive historic culpability and still plenty of current role to play. Only by letting those most responsible for creating and continuing the problem taste the fruits of their actions can we have even the slightest hope of action.

Horrible? Perhaps for some - but compared to what has already been happening in various other parts of the world... trivial so far.

Jim Hunt

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #14 on: February 25, 2014, 10:50:03 AM »
Only by letting those most responsible for creating and continuing the problem taste the fruits of their actions can we have even the slightest hope of action.

That doesn't really seem to be how things are working out in practice. The Economist has recently been discussing Jennifer Francis, the Arctic and the jet stream:

http://www.economist.com/news/science-and-technology/21596920-polar-warming-blame-americas-and-britains-bad-winter-weather-jet-set

In the wake of the recent UK floods it's also been discussing the political fall out:

http://www.economist.com/news/britain/21596933-knee-deep-floodwater-britains-politicians-rekindle-argument-about-global-warming-whither

Quote
Mr Cameron once sought, mostly unsuccessfully, to soften his party’s image with a green embrace; “Vote blue, go green”, was his slogan. But that now strikes many as ridiculous. The Tory environment minister in charge of Britain’s flood defences, Owen Paterson, is a climate-change sceptic. The energy minister managing Britain’s switch to low-carbon generation, Michael Fallon, calls global warming a “theology”. Mr Cameron, who has made no speech on the environment since 2010, reportedly urged his staff to cut the “green crap”—that is, subsidies for renewables and energy efficiency—from household bills. “Vote blue, get real”, a sniggering minister told Bagehot. “Green is so last year’s colour.”
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

ChrisReynolds

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #15 on: February 25, 2014, 11:49:21 AM »
What happened in England was Horrible, rain not seen in nearly 250 yrs. And indeed all over the Northern Hemisphere there were temperatures and conditions not seen before  in modern history. From Ice storms in Georgia US, to warmer weather in Alaska.
There has been some contentious debate about the role of Arctic Sea Loss and the meandering jet stream in relation to these events. How could we think that the loss of so much ice would not have a profound effect on the climate?

Can I suggest we need to start being careful with how we say things? (and the media fails very much as is shown by the 250 year thing).

Are we saying that 250 years ago there was actually more rain? Or are we saying that the current rainfall is unprecedented within the historical record? (which is a very different thing)

Anyway I for one am rather glad to see climate change impacts hitting the UK and US - two nations with massive historic culpability and still plenty of current role to play. Only by letting those most responsible for creating and continuing the problem taste the fruits of their actions can we have even the slightest hope of action.

Horrible? Perhaps for some - but compared to what has already been happening in various other parts of the world... trivial so far.

Top ten UK wettest winters in the Met Office record, which goes back to 1910...

2014 486.8
1995 485.1
1990 470.9
1915 463.1
2007 437.9
1916 433.0
1937 423.8
1994 422.9
2000 417.7
1920 402.3

What happened in the UK was problematic on a national scale, bad for some in certain regions. But the overall rainfall was not so massive when compared to 1916 or 1915.

I agree with ccgwebmaster - let's keep some perspective and not run away with ourselves. When people do that they make it easier for the denialists to play their stupid games.

Jim,

No things won't work out like that in practice, but at least the most culpable having their arses kicked makes a change from the way things usually work out.

bligh8

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #16 on: February 26, 2014, 03:40:06 AM »
What happened in England was Horrible, rain not seen in nearly 250 yrs. And indeed all over the Northern Hemisphere there were temperatures and conditions not seen before  in modern history. From Ice storms in Georgia US, to warmer weather in Alaska.
There has been some contentious debate about the role of Arctic Sea Loss and the meandering jet stream in relation to these events. How could we think that the loss of so much ice would not have a profound effect on the climate?

Can I suggest we need to start being careful with how we say things? (and the media fails very much as is shown by the 250 year thing).

Are we saying that 250 years ago there was actually more rain? Or are we saying that the current rainfall is unprecedented within the historical record? (which is a very different thing)

Anyway I for one am rather glad to see climate change impacts hitting the UK and US - two nations with massive historic culpability and still plenty of current role to play. Only by letting those most responsible for creating and continuing the problem taste the fruits of their actions can we have even the slightest hope of action.

Horrible? Perhaps for some - but compared to what has already been happening in various other parts of the world... trivial so far.

ccg

I was quoting news articles and cris r. I believe when I posted that remark, which was made in a historical sense. In that this was unprecedented in the last 250 years.

The loss of property or human life is a universal loss no matter where it occurs, just my feelings anyway.

It's difficult for me to see this as a blame thing....that said, most folks in the US live like kings or  are under the allusion the we do. That is one of the most profound things I learned when I was out sailing.

Most of my time out in the world was spent in third world countries....people are poor in a economical sense but in a human sense many parts of the third world are rich in many ways not considered in the western world. Family values and human interaction are deeply intertwined in some areas that are, in western terms very poor. People who lack personal transportation (cars) or bikes or horses or shoes for that matter would gather every Sunday morning....everyone from the whole area, hundreds of families with all of their children, in the town square to share a "pot luck" meal and show off their childrens best clothing, with local musicians providing music for the children to dance and share a festive moment.

For me it added a sense of what was important and what was real, the importance of possessions and social standings were not a part of the fabric of human existence. It was about food and water, sharing and helping, being involved with ones neighbors, contributing to a common goal of providing assistance to whoever within the community needed it.

I witnessed this time and time again from central America to Africa the theme was the same..it was a contented life and a better life or the hope of a better life for their children. Folks were not striving for "more" but for enough, for everyone.

When I traveled it was at face value, their were no rental cars or hotels or eating out...I was on a strict budget and a damn slim one at that.  I bought a 35 yr old S/V and worked on it for two years, everyday. I bought a book on sail design and a book on sail construction and a 50 year old Singer sewing machine and made mu own sails. I've had a love affair with the planet for the last 40 yrs only to stop by here, driven by my concerns over the unmitigated pollution of the planets Oceans only to find out that we, the inhabitants of this world are in the process of making it unlivable for everyone.

Sorry about my untimely response....

Best,
Bligh

ChrisReynolds

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #17 on: February 26, 2014, 08:48:24 PM »
Bligh8,

Probably best to stick to 104 years, since the official met office data only goes back to 1910. The Central England temperature record goes back something like 250 years (IIRC), but the official series only starts in 1878, that's as far as I go back with it because of the uncertainty with the earlier data.

bligh8

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #18 on: February 27, 2014, 12:57:08 AM »
Thanks Chris.....Then it was not you who had figured the percentage of something like that happening based of that 248 year number.  Guess I'm reading to much.
Best,
Bligh

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #19 on: February 27, 2014, 01:15:19 AM »
Thanks Chris.....Then it was not you who had figured the percentage of something like that happening based of that 248 year number.  Guess I'm reading to much.

If offhand memory serves, and apologies if wrong, the 250 year figure was derived from a very small (if not single) measuring station that had records that far back, suggesting that no rain had fallen in that specific location in greater quantity for the time period in question in the last 250 years.

That's very different from the whole of the UK or even just regional figures, and also doesn't give you a 1 in 250 year claim - as it doesn't inform that more rain did in fact fall 250 years ago (as implied by the most rain for 250 years part of the claim).

I just found it a sloppy bit of reporting all around when most people grabbed at the headline and variously interpreted it into all sorts of things it doesn't really mean. I'm not meaning to dispute that quite a lot of rain has fallen in quite an unusually prolonged way, or anything. Just that I didn't really agree with the way that headline was presented (and subsequently interpreted as the content propagated through news media). I think I saw it originally presented in this questionable way on a Guardian article but the general homogenity of the news media outlets would lead me to suspect it has been copied onto many of the rest as such (note the toothing hoax).

bligh8

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #20 on: February 27, 2014, 01:45:45 AM »
hey ccg

Both you and Chris have been at this a lot longer and are much better at disseminating info
than I am. Thus to a point I rely on info I read here and on associated blogs when I'm trying to get a clear picture of things.

Not meaning to deflect the thread....I wish your sailing adventure had turned out a little better for ya. Once your set and get out on the high seas there is nothing quite like it.

Best,
Bligh

Jim Hunt

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #21 on: February 27, 2014, 10:10:31 AM »
CCG - I don't know which "sloppy reporting" you've been reading, but the Met Office video above produced my "wettest January in England and Wales since 1766" quote.

The associated link goes to the EWP series data where they also provide details of a number of academic papers, none of which I have read. However the term "England and Wales" does suggest that more than one measuring station was involved "250 years ago". Error bars are however conspicuous by their absence!
« Last Edit: February 27, 2014, 01:00:27 PM by Jim Hunt »
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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #22 on: February 27, 2014, 12:06:32 PM »
This post may shed some light on the three rainfall series:

http://metofficenews.wordpress.com/2014/02/14/met-office-rainfall-records-how-far-do-they-go-back-and-what-can-they-tell-us/

It would probably be possible to extend the 1910 series further back (though with greater error bounds), but that would take money and someone would have to pay for it (eg DeFRA or similar).


Jim Hunt

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #23 on: February 27, 2014, 02:00:54 PM »
The latest Met Office news release concerning the UK's wettest winters:

http://www.metoffice.gov.uk/news/releases/archive/2014/early-winter-stats

The headline reads:

Quote
Early Met Office statistics for Winter 2014 show that England and Wales has already had its wettest winter in almost 250 years.

The article concludes by saying that:

Quote
These are provisional figures from 1 December 2013 to 25 February 2014 and could change after final quality control checks on data.

A full summary of the weather this January will be available on the Met Office website early in March.
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

ccgwebmaster

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #24 on: February 28, 2014, 10:59:22 PM »
CCG - I don't know which "sloppy reporting" you've been reading, but the Met Office video above produced my "wettest January in England and Wales since 1766" quote.

The associated link goes to the EWP series data where they also provide details of a number of academic papers, none of which I have read. However the term "England and Wales" does suggest that more than one measuring station was involved "250 years ago". Error bars are however conspicuous by their absence!

I think my argument is that we can't say wettest since, unless we're saying it was recorded as being wetter in 1766? Does the record go back further and therefore it was wetter in 1766? Or are we really saying we have no known precedent for greater rainfall in which case it's more accurate to say "wetter than at any point in the records"?

After all, to say it is the wettest since 250 years suggests it was wetter 250 years ago. As far as I know that isn't necessarily the case. Can we rule out that it's the wettest in 500 years? 1000 years?

What I'm really getting at here though isn't so much this one phrasing I feel communicates the wrong message - but that our whole way of thinking about, discussing and reporting on these sorts of events is now becoming meaningless.

Once we start to regularly exceed total historic records, we have no frame of reference with respect to them that can put an event in context. So this year we might say "wettest winter in England and Wales in any measurements we have", the year after next could be just slightly less wet - and it's only "the wettest winter since two years ago".

In short I think both the records and the reference to them is increasingly nonsensical as we transit into a new climatic regime. We need better ways of understanding the transition and the exceptionality of the events and their new context?

Jim Hunt

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #25 on: February 28, 2014, 11:22:16 PM »
Point taken CCG. In similar vein Peter Sinclair gave the Met Office a hard time about their use of language not so very long ago:

Dear Met Office

Quote
Your new post “The Recent Pause in Warming” shows zero understanding of the basic framing issues that have so damaged climate science communication over the last 2 decades.
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #26 on: March 02, 2014, 08:32:41 AM »
Here's UK rainfall (annual average), look at what happens at the end of the series for high annual rainfall (top right)!



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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #27 on: March 02, 2014, 01:00:02 PM »
Seems a remarkable change circa 1996. What happened then?

If it is global warming causing atmosphere to hold more water, shouldn't the change be more gradual?

Ice did begin a more rapid retreat about 1996 but should we expect immediate effect on rainfall distribution or a more gradual change?

Or perhaps that is an illusion with gradual change and random clustering often giving this sort of appearance?


There is also lack of low rainfall 1977 to 1993. Could that be a general global warming effect of atmosphere holding more water? Then ice retreat causes more extremes?

BornFromTheVoid

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #28 on: March 02, 2014, 01:57:53 PM »
I posted this on netweather a while ago, seems relevant here

I downloaded the monthly UK precipitation data from 1910, and posted a little analysis. Today I had a look at the months on that record that exceeded 2 standard deviations (σ) above the 1910-2012 averages for each month.
Below is a graph showing the numbers of months exceeding 2 standard deviations (σ) above average rainfall in each year.



Judging by the chart above, it seems that 2σ monthly rainfall totals have gone from occurring once every 4.3 years on average to once every 2 years.
 
The majority of this increase has occurred in the Winter half of the year (October to March)



Here, the likelihood of achieving a 2σ month during the winter half of the year has gone from roughly once every 25 years to once every 3.6 years
 
Summer (April to September) shows almost no trend at all.



Anywho, I thought these results turned out quite interesting. This year has started off continuing the trend, and if February ends up joining the list of 2σ months, it will be the first winter with 2 such months.
 
Feel free to point out mistakes and make suggestions!
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #29 on: March 02, 2014, 05:07:19 PM »
Seems a remarkable change circa 1996. What happened then?

If it is global warming causing atmosphere to hold more water, shouldn't the change be more gradual?

Ice did begin a more rapid retreat about 1996 but should we expect immediate effect on rainfall distribution or a more gradual change?

Or perhaps that is an illusion with gradual change and random clustering often giving this sort of appearance?


There is also lack of low rainfall 1977 to 1993. Could that be a general global warming effect of atmosphere holding more water? Then ice retreat causes more extremes?

That looks pretty noisy to me? What does a best fit line/curve look like? I mean - can you rule out noise and conclude that the increase is not indeed effectively gradual (particularly if ENSO cycles or other comparable effects are part of the fluctuations year to year - I must say I think the UK a little unlikely to have a nice consistent weather regime...). So without more evidence I personally would say gradual change with random clustering looking at the plot as above (possibly other plots would favour other interpretations though - ever the problem with statistics). Also putting any sort of line through the data might mislead if the amplitude of the signal is changing but not so much the mean? (I daresay there are also ways to take that into account on the plot)

That said I think this is worth a mention - it suggests it is possible (and is happening) to get abrupt changes in rainfall levels (at least to the dryer side, but I can't see why the reverse shouldn't occur too):

http://onlinelibrary.wiley.com/doi/10.1029/2006GL028628/abstract

The key point being - abrupt - as model forecasts lead us to expect increasing extremes of precipitation, they just don't (to my knowledge) forecast abrupt transitions.  The paper is paywalled, or one could try to see how it might relate to the UK.

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #30 on: March 02, 2014, 06:10:56 PM »
Crandles,

I've found no relationship between precipitation and temperature indicating that large scale dynamic processes may be playing a role. However I've been looking at the entire period from 1910 to date, and using UK local temperature, whereas ocean temperature and temperatures at the source of air masses may be playing a role I've not detected / is lost in variability due to large scale processes (e.g. NAO).

I've attached a plot by season - I've calculated anomalies from the seasonal mean for 1951 to 1980 and present anomalies from that mean. There is no clear pattern accounting for the change (post 1998), just a general shift in tendency to more positive anomalies. With regards the 1998 super El Nino - the question this poses is that we've had large Nino's before, but the behaviour in UK rain is evidently unique in recent decades. The AMO would be a prime candidate - the Atlantic is the source of much UK rain - but we've had two cycles since 2010. However N Atlantic SST has jumped during the time period concerned.
http://www.nature.com/ncomms/journal/v2/n2/images_article/ncomms1186-f1.jpg
And that is due to GW.

Maybe I should try looking at zonal flow over the UK (500mb) and see if the positive seasons are for zonal flow from the Atlantic...

BFTV,
Thanks for that very useful. I've recalculated the anomalies as fractions of sigma for 1951 to 1980 and find similar behaviour to what you've posted.

CCGWebMaster,

The change is rather clear and substantial from the graph, but I've posted a timeseries with a linear trend as an attachment.

As I said to Crandles, N Atlantic SST may be a causal factor - increased SST means more evaporation. But I'm looking at this as more the start of a trend. AGW is favouring a tendency to high precipitation anomalies when atmospheric (synoptic scale) conditions are right, manifesting itself as an increase in variance with greater highs. The histogram is clearly not a normal distribution (so the use of std dev isn't really sound - but it's not an unreasonable technique to get a view of records). While I'm at it I've attached the histogram. Comparing the distribution shown (note 1200mm) with the scatter plot posted above shows that the rightwards extension of low occurrence events is almost all caused by the recent shift.


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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #31 on: March 02, 2014, 06:29:57 PM »
I've got AMO data from this page.
http://www.cgd.ucar.edu/cas/catalog/climind/AMO.html

And it's plotted below. The true AMO is the global warming signal subtracted from N Atl SST. Looks to me like the increase in rainfall is being driven by AGW warming of the oceans, with a small component from the AMO proper.



crandles

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #32 on: March 02, 2014, 09:41:26 PM »
Thanks for answers :)

I imagine that attributing UK changes is rather difficult because of being close to jet stream. Just a small subtle change to jet stream could cause large consequences or it could just be random noise causing apparent small subtle change to jet stream.

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #33 on: March 03, 2014, 07:03:50 PM »
The scatter plot of N Atlantic SST and UK ann avg rainfall only shows a marginal shift post 1998 - the problem is it includes some dry summers and they're only going to add to noise. What I'm testing is whether over 1910 to 2010 there is a relationship between N Atl SST and UK rainfall.

If I get the time tonight I'll use average pressure in a box over the UK to determine if a month/season is Atlantic oriented (i.e. dominated by lows drawing in Atlantic air) - maybe I should be using zonal flow...

Using that I'll select out the subset of months/seasons so as to avoid noise from periods that can't contain a signature from the Atlantic. Zonal flow would probably be the best 'gatekeeper' for such a further analysis.

The problem is the AMO SST data I have only goes up to 2010, however at the loss of only the 2012 record wet year I'll probably put up with that. If I used NCEP/NCAR SST timeseries I can only get back to 1948.

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #34 on: March 06, 2014, 03:10:38 PM »
The Met Office have now published their "Provisional assessment of the weather experienced across the UK during Winter 2013/2014"

As well as the things already mentioned here, they state that:

Quote
An analysis of pressure fields by University of East Anglia suggests this winter has had more severe wind storms than any other winter season in a series from 1871.

As some sort of compensation for all the hardships so recently endured by us Brits, they have also officially announced that "Spring has sprung!"
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #35 on: March 09, 2014, 03:23:47 PM »
All of which reminds me that I've neglected to mention a recent article of my own on this very topic!

http://econnexus.org/the-weather-report-from-soggy-south-west-england/

According to the Daily Telegraph, David Cameron believes that:

Quote
Man-made climate change is one of the greatest threats to the UK and the rest of the world.

Actions speak louder than words David (and Barack for that matter)
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #36 on: March 16, 2014, 10:15:07 PM »
The NOAA Ocean Prediction Center just published a piece on the record number of hurricane-force storms in the Atlantic, I've just blogged on this and the UK impact.

See: http://a4rglobalmethanetracking.blogspot.com/


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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #37 on: March 18, 2014, 12:09:04 PM »
Thanks for the heads up A4R. I've now blogged about it too, along with lots more from the Met Office plus a little local colour:

http://econnexus.org/stormy-winter-weather-moves-south/

See the NOAA map of North Atlantic wind speed anomalies for January-February 2014 for a graphic overview:
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #38 on: March 25, 2014, 02:11:38 PM »
http://www.bbc.co.uk/news/science-environment-26731790

Quote
British winters are likely to become milder and wetter like the last one but cold spells still need to be planned for, says the UK Met Office.

Summers are likely to be hotter and drier, but washouts are still on the cards, it adds.

The assessment of future weather extremes finds the role of human influence is "detectable" in summer heatwaves and in intense rainfall.]British winters are likely to become milder and wetter like the last one but cold spells still need to be planned for, says the UK Met Office.

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Re: Met Office (UK) "suggests climate change link" on recent storms
« Reply #39 on: August 28, 2014, 12:15:10 AM »
New paper in Nature Climate Change:

Huntingford et al. 2014,  Potential influences on the United Kingdom's floods of winter 2013/14.
http://www.nature.com/nclimate/journal/v4/n9/full/nclimate2314.html

See also
http://phys.org/news/2014-08-scientific-potential-uk-winter.html

Figure 6 of the paper (from the first link above):