Is recent flooding and heavy rainfall unusual?

I've written at length about the excessive rainfall the UK has experienced, particularly last year but also since the late 1990's; six out of the years from 1998 to 2012 are in the top ten wettest on record, based on Met Office rainfall data which began in 1910.

There are various theories as to why our summers have been so wet, and why the jet stream has been further south than normal.

It's worth remembering as exceptional as the last few years have seemed, climate history shows us that flooding in the UK has always been normal.

This point is highlighted in research which was carried out by Durham University following the serious summer floods in 2007 and highlighted on the Watts Up With That website this week.

The research is five years old, but it rings very true today, and the prediction made in 2008 of increased flooding and heavy rainfall in subsequent years has proved to be all too correct.

The author Professor Stuart Lane looked back at rainfall patterns starting in the mid 1700's.

He concluded that our climate has always fluctuated between very wet and very dry periods, some of which lasted for a few decades.

Crucially the period from the early 1960's to the late 1990's saw far fewer river flooding episodes compared with before the 1960's and after the 1990's.

Ominously, he points out that because more than three quarters of our flood records started during the 1960's, when there were far fewer river flooding episodes, we have underestimated the frequency of flooding.

And this has a knock on effect as to how much flood plain development local authorities will allow.

It's a vicious circle as more flood plain development is likely to make any future flooding even worse.

The article on the Durham University website can be found by clicking here.

UK weather outlook:

The heavy snow that brought disruption to parts of the UK on Friday has melted rapidly as a result of milder air and rainfall.

The next 48 hours will be dominated by a very common January weather pattern, with a powerful jet stream bringing rain or showers to all areas, accompanied by strong to gale force winds.

There's uncertainty about Friday's weather though, with an Atlantic depression expected to bring rain to parts of the UK.

Just how far north the rain will come is open to question, but with colder air pushing southwards as it clears away, some of it could turn to snow.

2012 Global temperatures:

Provisional Met Office figures show that 2012 was the 9th warmest on record, 0.45C above the 1961-1990 average. This is very close to their prediction for 2012 which was for a global temperature 0.48C above the 1961-1990 average.

According to the UAH satellite temperature measure, 2012 was also the 9th warmest on record.

Follow me on twitter @Hudsonweather

Comments

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  • Comment number 133. Posted by quake

    on 5 Feb 2013 10:36

    Increasing CO2 in the atmosphere reduces the heat loss of the oceans. Heat then builds up which causes heat loss to rise, until heat loss again balances with heat in (from the sun).

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  • Comment number 132. Posted by QuaesoVeritas

    on 5 Feb 2013 09:59

    #128 - greensand wrote:
    "Sorry, should have explained that the chart shows 30 year rolling "linest" trends ending in Dec 2012."

    Should that be "linear" - finger trouble?

    #127:

    "Semi related have a look at the chart below, appears to show land datasets leading SSTs can sort of comprehend that, larger heat sink etc. But then why do we look to SSTs, PDO, ENSO, AMO etc as drivers of global temps?"

    I am not sure if the chart shows land temperatures leading SST, they look as if they are changing at the same time to me. Of course they are monthly figures, so SST could be leading land on a shorter timescale, or vice versa. Yes, the trend on land is currently higher than for the sea but as you say, that may be due to the fact that the sea is a much larger heat sink.

    Having said that, I am also not sure if most people would say that ocean temperatures are the driver of global temperatures. *If*, the increase in global temperatures is related to CO2/greenhouse effect, then logicially any increase would happen in the atmosphere. I am not sure how any heat would get into the ocean, other than via the atmosphere.

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  • Comment number 131. Posted by greensand

    on 5 Feb 2013 08:54

    118. lateintheday wrote:

    “it looks like that large pool of subsurface cool water (eastern pacific) seems to be making its way to the top.”

    Maybe, just maybe, latest BOM numbers for week 28th Jan to 3rd Feb (previous week in brackets)

    Nino 1 -0.21C (-0.08C)
    Nino 2 -0.46C (-0.07C)
    Nino 3 -0.74C (-0.51C)
    Nino3.4 -0.49C (-0.26C)
    Nino 4 -0.01C (+0.11C)

    http://www.bom.gov.au/climate/enso/indices.shtml?bookmark=nino3.4

    select “variable” for different zones, data accessed by “Data sorted by date”

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  • Comment number 130. Posted by newdwr54

    on 5 Feb 2013 08:02

    129. ashleyhr:

    "UK January 2013 mean temperature was 3.3 C - around 0.2 C or 0.3 C below average I think."

    It depends what you mean by 'average' ashley. As far as I know the Met now uses the 1981-2010 base period to calculate anomalies in the UK record. If so, then January 2013 was -0.4C below average, and winter to date (Jan-Feb) is -0.3 below average.

    Oddly though the 30-year January trend (the rate at which January temperatures in the UK have changed over the past three decades) has increased from +0.3C per decade to +0.4C per decade. This is because, despite the relatively cool January this year, a spate of January's in the mid 1980s were much cooler, while those in the mid 2000s tended to be much milder.

    We'd need to see temperatures around -11.6C below the February average this year if the Daily Express prediction of 'Coldest winter in 100 years' is to be realised. CET anomaly is currently 0.0C (provisional to 3rd).

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  • Comment number 129. Posted by ashleyhr

    on 5 Feb 2013 01:08

    UK January 2013 mean temperature was 3.3 C - around 0.2 C or 0.3 C below average I think.
    http://www.metoffice.gov.uk/climate/uk/datasets/Tmean/date/UK.txt
    Also rainfall fairly similar to 2012 and 2011 (slightly below normal I think).

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  • Comment number 128. Posted by greensand

    on 4 Feb 2013 23:40

    Re 127

    Sorry, should have explained that the chart shows 30 year rolling "linest" trends ending in Dec 2012.

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  • Comment number 127. Posted by greensand

    on 4 Feb 2013 23:34

    126. QuaesoVeritas wrote:

    "...I wasn't expecting an answer."

    Good, cos it doesn't look like you are going to get one, well not from me! I have 2 DVDs full of data in a format that apparently requires the laptop they were created on? All now in the hands of the family “expert”, I fear it is time to move on.

    Semi related have a look at the chart below, appears to show land datasets leading SSTs can sort of comprehend that, larger heat sink etc. But then why do we look to SSTs, PDO, ENSO, AMO etc as drivers of global temps?

    http://i49.tinypic.com/24ee69h.jpg

    Chart presentation is lacking but I think it gets the message over?

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  • Comment number 126. Posted by QuaesoVeritas

    on 4 Feb 2013 23:17

    #125. - greensand wrote:
    124. QuaesoVeritas wrote:

    "Interesting question, seem to recall reading some work on the relationship between SSTs and their immediate atmosphere, will have to have a dig, think it might have been CRU but not sure."

    Don't go to any trouble, it was really a rhetorical question and I wasn't expecting an answer.

    Actually, thinking about it, it would be very difficult, certainly in the past, to measure atmospheric temperatures over the sea in the same way as they do over the land, so taking the temperature of the actual sea surface is probably the only practical solution.

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  • Comment number 125. Posted by greensand

    on 4 Feb 2013 21:05

    124. QuaesoVeritas wrote:

    "What about the atmosphere over the sea?"

    Interesting question, seem to recall reading some work on the relationship between SSTs and their immediate atmosphere, will have to have a dig, think it might have been CRU but not sure.

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  • Comment number 124. Posted by QuaesoVeritas

    on 4 Feb 2013 20:32

    #122. - greensand wrote:
    "So not sure how indicative SSTs will be? With 70% of the surface being sea you would think they would be!"

    What has always puzzled me is that the non-satellite anomalies are based on SST and atmospheric temperatures over land. What about the atmosphere over the sea?

    AFAIK, the statellite figures are all based on atmospheric temperatures, whether over land or sea.

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