By Paul Homewood
The Guardian, reporting on some recent research from Oxford University, comment:
They say:
Climate change caused by humans has made the likelihood of extreme rainfall similar to that seen in England this winter significantly higher, according to analysis seen by the Guardian.
Rainfall events that would previously have occurred only once in a century are now likely to be witnessed once every eighty years in the south of England, the Oxford University work shows.
That will mean far more frequent severe floods for residents of the crowded region, with what were once extremely rare events now happening much more often than the infrastructure of the region is equipped for. The research shows an increase in the rate of such events of about 20 to 25%, which significantly alters the number of homes likely to be vulnerable to flooding.
http://www.theguardian.com/environment/2014/apr/30/climate-change-extreme-rainfall-england-flooding
The first thing to point out is that these results are based on climate models, rather than real world data. As the authors point out:
However, while our findings are statistically robust, the result depends on how man-made climate change is represented in the experiment. We used different climate models to estimate the pattern of global warming which provided a range of possible changes in risk. In several cases, the models gave no change or even a reduction in risk, but overall the simulations showed a small increase in the likelihood of extremely wet winters in the south of England.
They also describe their study thus:
Following preliminary assessments from the Met Office, Oxford University researchers undertook the first scientific experiment to analyse whether the risk of extreme rainfall has changed owing to climate change after the winter deluge between December 2013 and February 2014. Total rainfall in Oxford over the three months was the highest ever recorded by the University’s Radcliffe Observatory since it was set up 200 years ago.
Scientists used the spare capacity on volunteers’ home computers to compare tens of thousands of simulations of possible weather in our present-day climate with tens of thousands of simulations of a hypothetical world without the influence of past greenhouse gas emissions in the atmosphere using the same climate model. Comparing numbers of extremely wet winters between these two groups provides estimates of the influence of climate change on the UK weather. They found that a one-in-100-year winter rainfall event (i.e. a 1% risk of extreme rainfall in the winter of any given year) is now estimated to be a one-in-80 year event (i.e. a 1.25% risk of extreme rainfall in any given winter), so the risk of a very wet winter has increased by around 25%.
http://www.ox.ac.uk/news/2014-04-30-global-warming-makes-very-wet-winters-more-likely
Still, let’s see what the real data tells us.
Despite last winter being the wettest on record since 1910 in the South of England, there is no evidence to suggest that wet winters are becoming more common. The wettest 10 years were between 1911 & 1920.
Figure 1
However, we need to recognise that the selection of the narrowly defined period of “December to February” has very little relevance. If there are concerns about “extreme rainfall and flooding”, we should be looking at the months that are traditionally the wettest. In the South of England, these are October to December.
http://www.metoffice.gov.uk/public/weather/climate/oxford-oxfordshire#?tab=climateGraphs
When we analyse these months, we find that the wettest year was 1929, followed by 2000 and 1960. (Oct-Dec rainfall in 1929 totalled 457.7mm, compared to 408.5mm this last winter).
Wet years in 2000 and 2002 pushed the 10-Year trend up to similar levels seen in the 1910’s, but the trend has fallen again since.
Also evident is the well accepted “dry period” of the 1960’s and 70’s. As with the winter trends, there is no evidence that Oct-Dec periods are becoming wetter.
Figure 2
Of course, the study talks about “extreme rainfall”, rather than averages, so is there any evidence that this is becoming more common?
It is important to recognise that the reason why the winter of 2013/14 was so wet was because the wet weather persisted for three months. (It is also worth recalling that the even wetter weather of 1929 persisted for four months, from October to January).
This persistence is a factor of weather and coincidence, rather than having anything to do with a warmer climate. Therefore, to establish whether rainfall, per se, is becoming more extreme and intense, we need to look at monthly figures, rather than seasonal ones.
Figure 3 shows the top 20 wettest months, falling in the October – December period, since 1910 for England South.
Clearly, the wettest months occurred in the early decades. Since 1970, only one month, Oct 2000, has exceeded 160mm, compared with nine such months up to 1970.
Figure 3
Finally, let’s take a look at the Oct-Dec rainfall trends at Oxford itself, where data is available back to 1853. As with England South, the three stand out years are 1929, 1960 and 2000.
In the last decade, we have seen nothing that was not commonplace between 1870 and 1920.
Figure 4
Conclusions
There is no evidence that “extreme rainfall” is becoming more common.
The study’s authors seem to have gone to a lot of bother, trying to establish a link to global warming. They would have saved themselves a lot of work, if they had simply gone and analysed the data.
Sources
1) All precipitation data for England South from Met Office
http://www.metoffice.gov.uk/climate/uk/summaries/datasets
2) Oxford rainfall data
http://www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/oxforddata.txt
3) Details of the Oxford University study.
http://www.ox.ac.uk/news/2014-04-30-global-warming-makes-very-wet-winters-more-likely
http://www.climateprediction.net/weatherathome/weatherhome-2014/results/
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
That is a good total. Did CAGW peak in this area in 1985? We got that much in 7 hours.
Anbother set of numpties who think that running a climate model is an experiment. No wonder the UK is in serious decline if this is what Oxford University is doing these days.
now happening much more often than the infrastructure of the region is equipped for….
huh?…..the infrastructure can support a flood every 100 years…
…but not every 80 years?
Dear Lord, what kind of infrastructure do you guys have over there?
Nice work, but tell us something we don’t know.
The Guardian is frantically going out of its way to ‘prove’ global warming by whatever means necessary. This latest ‘definitive report’ is just another piece of absurdly biased climate propaganda.
It’s what they do. They won’t come out of this well.
Should we begin building an ark now, or wait till later?
Sorry about that, I’ve been reading all of these rent-a-catastrophe reports, and between extreme rains and rising sea levels it appears we’re being sold the idea that Man is capable of creating catastrophes of biblical proportions. Without, apparently, angering a god who the warming alarmists will say doesn’t exist anyway. Nope, gonna do it all by ourselves.
OK. It rains in England. A lot. The Gulf Stream and prevailing Westerlies blow in moisture from the Atlantic and it drops as rain over England. It’s been doing that a long time now. It’s going to keep right on doing that regardless of any decrees coming from Whitehall or the White House. Buy a decent foul-weather outfit and get used to it.
It has to be remembered that in the old days the citizens of the UK thought for themselves. They lived on high ground and graised their livestock on the floodplains in summer. Nowadays the Government decrees that farming for food is not necessary and encourages people to live and work on the floodplains. The dumbing down of education means that millions of people are quitre happy to buy a house on a floodplain.
Show us the heat, man…. show us the HEAT!!!
What rise in temp?
“They would have saved themselves a lot of work, if they had simply gone and analysed the data.”
True on almost all alarmist claims, but then alarmists couldn’t make alarming claims if they actually used data. Tough to be an alarmist and a scientist of integrity.
They would have saved themselves a lot of work, if they had simply gone and analysed the data.
but results would have been ‘worthless ‘ from the fill your boots with grant cash , point of view.
Lets face it ‘the cause ‘ has [led] to wide scale use of science by press release , and great claims made on little or no evidence , while its created a ,models mean more than facts outlook . You want to get published , you want to get paid , then you know what results you need to produce!
They say: ” Rainfall events that would previously have occurred only once in a century are now likely to be witnessed once every eighty years in the south of England, the Oxford University work shows.”
Correct me if I am wrong but that means this type of rain event will occur 5 times every 400 years instead of 4 times.
Yet they claim “the likelihood of extreme rainfall similar to that seen in England this winter significantly higher” . How is 1 more time per 400 years a “significantly higher” occurrence?
They also claim “That will mean far more frequent severe floods for residents of the crowded region, with what were once extremely rare events now happening much more often”. How is 1 more time per 400 years “far more frequent” and how does that 1 extra event per 400 years change a “once extremely rare event” into something else?
Climate change ‘making extreme rainfall in England more likely’.
————
Who cares about data? They said EXTREME!
We’re DOOOOOOMED!
A computer model science study should be illegal to publish without scientific observations/evidence to verify it using scientific method. A computer model on its own means absolutely nothing and no paper should report this rubbish.
Oxford University researchers undertook the first scientific experiment to analyse whether…..
Cambridge University researchers found exactly opposite:
http://www.vukcevic.talktalk.net/Oxbridge.htm
If you take the report seriously (or if “one” takes the report seriously), isn’t the most important implication that you should invest in better flood control in the affected region? Flooding every 80 years instead of every 100 years does not strike me as a reason to sacrifice your economy to wind farms.
Tom in Florida: Correct me if I am wrong but that means this type of rain event will occur 5 times every 400 years instead of 4 times.
That’s about the size of it.
Calling computer program outputs “experiments” gives new meaning to the term “artificial intelligence.”
Timely reminder with the release of Noah.
.
How can you statistically extract periodicities of events from data that is only about the same length as the period of interest?
ClimatePrediction.Net is the source of the projections. The same crowd (e.g. Myles Allen) who predicted up to 11 degrees celsius increase in temperature before the end of the centurydue to AGW.
AJB says:
May 7, 2014 at 11:54 am
“Follow up project coming soon here.”
Mod.: Spam? (link, “here”)
[Good find, thank you. Mod]
Of course they should have analysed the data, but there is an inherent problem in doing that using real-world (unadulterated) records. As these are typically unable to conform to the assumptions (wishful thinking) used by climate scientists in their heat-seeking models they would never have been able to publish scary ‘research’.
If all climate science were based on accurate, unadulterated and un-cherry-picked data the world would be a much better and much happier place. Except for the politicians who would be unable to keep justifying their new tax raising abilities and of course those whose livelihoods and often massive wealth are entirely dependant on maintaining the gullible warming scare.
ps Don’t you just love the creative thinking in describing the model output which showed a 1 in 100 chance changing to a 1.25 in 100 chance (i.e nothing here to worry about) as a ‘25% increase’ in likelihood of extremely wet winters which sounds a whole lot scarier ….
Overall they torture the models until the desired result is reached. Here is what happens when you are more humane and desist from cruel torture.
UK to get more drought
http://dx.doi.org/10.1016/j.jhydrol.2010.04.035
UK to get more rain
http://dx.doi.org/10.1002/joc.1827
Hey that wasn’t spam! There’s little difference between this crowd sourced nonsense that writing a shared game. Maybe I shoulda used the /sarc tag.
[Yes, that would have helped. Mod]
[Then again, the crowd-sourced game might be a more accurate GCM. Mod]
GIGO.
So the next one is in 80 years time. If their simulation is wrong they would have been just a thing of the past. Children won’t know what an Oxford researcher is. Next.