Guest post by Paul Homewood
h/t Robuk
A study, by Professor Stuart Lane of Durham University back in 2008, appears to have been remarkably percipient. Written just after the extremely wet summer of 2007, the study suggests that, far from summers in the UK becoming drier as most climate models predict, they are likely to become wetter.
Lane makes the following points.
- The wetter weather in 2007, and which he forecasts will continue to be the pattern, is the result of the movement of the jet stream onto a more southerly track. (This, of course, is exactly what happened in 2012).
- The period 1960-90 was an unusually dry one, especially compared to the 19th and early 20thC.
- Three-quarters of our flood records start in the flood-poor period that began in the 1960’s. As a result, the frequency of flooding has been underestimated, leading to building on flood plains, etc.
- Examining seasonal rainfall data and river flow patterns back to 1753, suggests many other “flood-rich periods” in the past which are comparable to now.
- We have forgotten “just how normal flooding is in the UK”.
- Linking heavier rainfall to global warming was wrong.
News Release
Last summer was the second wettest on record and experts who have studied rainfall and river flow patterns over 250 years say we must prepare for worse to come. Professor Stuart Lane, from Durham University’s new Institute of Hazard and Risk, says that after about 30 to 40 less eventful years, we seem to be entering a ‘flood-rich’ period. More flooding is likely over a number of decades.
Prof. Lane, who publishes his research in the current edition of the academic journal Geography, set out to examine the wet summer of 2007 in the light of climate change. His work shows that some of the links made between the summer 2007 floods and climate change were wrong. Our current predictions of climate change for summer should result in weather patterns that were the exact opposite of what actually happened in 2007. The British summer is a product of the UK’s weather conveyor belt and the progress of the Circumpolar Vortex or ‘jet stream’. This determines whether we have high or low pressure systems over the UK. Usually the jet stream weakens and moves northwards during spring and into summer. This move signals the change from our winter-spring cyclonic weather to more stable weather during the summer. High pressure systems extend from the south allowing warm air to give us our British summer.
In 2007, the jet stream stayed well south of its normal position for June and July, causing low pressure systems to track over the UK, becoming slow moving as they did so. This has happened in summer before, but not to the same degree. Prof. Lane shows that the British summer can often be very wet – about ten per cent of summers are wetter than a normal winter. What we don’t know is whether climate change will make this happen more in the future.
However, in looking at longer rainfall and river flow records, Prof. Lane shows that we have forgotten just how normal flooding in the UK is. He looked at seasonal rainfall and river flow patterns dating back to 1753 which suggest fluctuations between very wet and very dry periods, each lasting for a few years at a time, but also very long periods of a few decades that can be particularly wet or particularly dry. In terms of river flooding, the period since the early 1960s and until the late 1990s appears to be relatively flood free, especially when compared with some periods in the late 19th century and early 20th Century.
As a result of analysing rainfall and river flow patterns, Prof. Lane believes that the UK is entering a flood rich period that we haven’t seen for a number of decades. He said: “We entered a generally flood-poor period in the 1960s, earlier in some parts of the country, later in others. This does not mean there was no flooding, just that there was much less than before the 1960s and what we are seeing now. This has lowered our own awareness of flood risk in the UK. This has made it easier to go on building on floodplains. It has also helped us to believe that we can manage flooding without too much cost, simply because there was not that much flooding to manage.” He added: “We have also not been good at recognising just how flood-prone we can be. More than three-quarters of our flood records start in the flood-poor period that begins in the 1960s. This matters because we set our flood protection in terms of return periods – the average number of years between floods of a given size. We have probably under-estimated the frequency of flooding, which is now happening, as it did before the 1960s, much more often that we are used to. “The problem is that many of our decisions over what development to allow and what defences to build rely upon a good estimate of these return periods.
The government estimates that 2.1 million properties and 5 million people are at risk of flooding. In his review of the summer floods Sir Michael Pitt was wise to say that flooding should be given the same priority as terrorism.” Professor Lane concluded: “We are now having to learn to live with levels of flooding that are beyond most people’s living memory, something that most of us have forgotten how to do.”
Flooding is one of the issues covered by the Institute of Hazard and Risk Research at Durham University where Prof. Lane is a resident expert. The IHRR, which launches this week, is a new and unique interdisciplinary research institute committed to delivering fundamental research on hazards and risks and to harness this knowledge to inform global policy. It aims to improve human responses to both age-old hazards such as volcanoes, earthquakes, landslides and floods as well as the new and uncertain risks of climate change, surveillance, terror and emerging technologies. Prof. Lane’s research is funded by the Willis Research Network, an innovative collaboration between universities worldwide and the insurance industry, and The UK Research Councils’ Rural Economy and Land Use Programme.
http://www.dur.ac.uk/news/newsitem/?itemno=6468
Perhaps Julia Slingo should read this paper.
Related articles
- UK Rainfall 2012-The Report The Met Office Should Have Produced (wattsupwiththat.com)
- 2012 second wettest year on record for UK (guardian.co.uk)
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I wonder how the IPCC “consensus” handles non-consensus views such as this. Once you have arrived at a consensus, does that mean that alternate views are “contrarian”, and have no place in your consideration?
The Unique Solution Syndrome concept says that the IPCC will proceed exactly in this way. The pile of papers has been determined: on the left are the “correct” papers, those that are to be used in AR5, AR6 etc. On the right are the “incorrect” papers, the ones to be dismissed because, by the precept that once the truth is known, all views that are inconsistent with the truth must be wrong. It does not matter how large the righthand pile becomes relative to the left. The truth is not determined by volume.
And there is the paradox. “Volume” is how one determines consensus. But in a worldview where consensus determines “truth”, further consideration is not about consensus at all, but about truth. What earlier would have been considered in determining consensus is now considered relative to the DETERMINED TRUTH. “Volume”, i.e. majority opinion, no longer has the value it did when first used, and, in fact, has negative value if a large amount of opinion rises to challenge the consensus. Conspiratorial nuttiness and malfeance abounds for thoughts that previously were legitimate points of discussion.
We are in interesting times. During the last 25 years we have witnessed the creation of dogma, of a meme, that now struggles for surival. How this plays out will be very interesting.
The pattern of changes in extremes uncovered by the research matches the predictions made in a number of climate models. Dr Fowler, author of the study at Newcastle University, claims ‘the changes in the 40 year period are consistent with the trend we would expect from global warming’.
But Philip Eden, one of the country’s leading and most respected climatologists, argues that the claims could be misleading. The problem, he says, is down to the short period of rainfall statistics analysed.
He claims that by taking a much longer time period, for example the whole of the 20th century, the frequency of high intensity rainfall events that we have witnessed in the past 30 years is not unusual.
The eras of heaviest summer downpours have actually coincided with cooler summers, not warmer summers, in particular 1912-1931, and again from 1948-1969.
In autumn and winter, downpours are closely linked with the strength of westerlies, which were very low in the 1960s, the start point of the study, and reached a peak between 1988 and 2002, he continued.
THEN THE GETOUT,
That said there does seem to have been more incidences of flooding in the last couple of decades.
http://www.bbc.co.uk/blogs/paulhudson/2010/11/is-the-perceived-rise-in-flood.shtml
The relationship between Lamb weather types and long-term changes in flood frequency, River Eden, UK
https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/11519/6/Lamb_Weather_Type_Final.pdf
Over Christmas I did a lot of walking with my dogs across rural Hampshire.
I noticed something for the first time, or rather, something registered for the first time.
Many fields have drainage ditches in them. Most are deep and all were full. I’ve walked over these fields many times but had never really noticed the ditches until now. Somebody must have made them and they must have been made as deep as they are in response to the conditions prevailing at the time.
This tells me that the rain we suffered last year in England is not unprecedented and is expected, at least by the farmers that made the ditches. All part of natural variability.
Been up too my knees in water in some fields this year. There’s a name for them. Yes, that’s it: water meadows.
In my hometown (Worcester, England) has a record of high floods going back several hundred years engraved on a gate house that leads from the cathedral precincts to the river. Just downstream of that town is Tewksbury that got badly flooded in 2008, follow the link for a photo of it. http://www.guardian.co.uk/environment/2008/jun/25/flooding.insurance Most of the old stuff is high and dry whilst the modern in underwater.
This is no surprise – if you want a good history on flooding in UK go read Doe’s book:
Doe, R. 2006 “Extreme Floods – a history in a changing climate” Sutton Publishing.
Some folks up above wondered if the sea level was higher in the past. The answer is a bit more convoluted than I like, but looks to be ‘mostly yes’.
http://chiefio.wordpress.com/2013/01/29/is-there-a-sea-level/
so looks like ‘sea level’ wanders around a lot all on its own…
I should add to my above comments that Jakarta, a truly monsoonal city, averages 1,700mm of rainfall a year, most of that between November and April, peaking at over 300m a month in January and February.
London on the other hand has an average of about 600mm of rainfall a year, spread pretty evenly throughout the year, though with a wetter period of over 80mm per month average ‘precipitation’ during October, November, December and January.
So London has some way to go before you find yourself wading across the foyer of the Dorchester Hotel because the long lost Westbourne River has burst its banks at the Serpentine in Hyde Park.
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