In saying “this is the worst rain for 200 years”, what they mean is it’s the worst rain in the weather record, and that the weather record goes back 200 years.
It may in fact be the worst rain for 201 years or 2001 years, we don’t know because we don’t have those records.
What we do know is that the UK has been getting wetter and wetter and wetter. Flooding is now three times as likely as it used to be and pretty much all rainfall records have been broken in recent years.
Bear in mind that the current flooding is mainly affecting southern England. Last month was the wettest on record here (the record dates back to 1766) and it looks almost certain that it will be the wettest winter on record. However, during the same period there have been parts of the UK, Scotland in particular, that have been unusually dry.
Compared to the floods of 2007, these ones aren’t as bad. In 2007 about eight times as many properties were flooded in a band stretching from Bristol northeast up to Hull, places such as Gloucester and Sheffield were particularly badly hit. Rainfall levels during Autumn 2007 are considerably higher than those for winter 2013/4.
The weather of late has been extremely unusual in that the UK has been hit by one storm after another, more storms in the last two months than would normally be the case in a decade. It’s also been exceptionally mild which means that the precipitation has fallen as rain rather than snow.
2012 as a whole was an extremely wet year (only 2000 was wetter – just). The drought that lasted until March 2012 ended abruptly and reservoirs and the water table were quickly replenished. Since then water levels have remained high, the rain that’s been falling has nowhere to go. The ground is completely saturated and in places the water table is now at ground level.
Even a modest amount of rainfall will cause further flooding, and the water table will keep rising for several days yet, so even if there’s no rain then some places will see the flooding worsen. It’s at a point now where some places are going to remain underwater for several months, even if we have a dry spring.
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COMMENT: TO MICHAEL
The River Thames, like other UK rivers, is at all time record levels. It’s caused flooding to properties that have stood for centuries without problems. Building on flood plains is indeed a problem and this makes matters worse but the flooding isn’t restricted to just these areas. In recent years there has been extensive flooding in Glasgow, Carlisle, Hull, Sheffield, London, Leeds etc – none of these are on flood plains.
Flood levels are a lot higher than they used to be and it’s largely thanks to flood defences that matters aren’t much worse. In the recent flooding more than a million properties have been protected from the flooding. In December we had a storm surge even higher than the one in 1953, back then thousands of people lost their lives in Holland and the UK but this time not a single life was lost.
The claim that this is the worst on 200 years is not correct.
If we look at 2-month precipitation numbers during autumn and winter in the region, we find that this latest period of December/January has been exceeded on eight occasions since 1910. In other words, it is, on average, an event that happens pretty much every decade or so. A couple of points stand out: 1929/30 stands well above the rest, and on all three graphs. There is no evidence that recent years have been unusually wet, compared to earlier decades.
Before anybody gets carried away with claims of ”record rainfall? that we keep hearing about in the UK, let‘s consider the facts. In the UK as a whole, January was only tie 17th wettest month since 1910, with 183.8mm. Relatively speaking, last month was wetter in England & Wales, but even there it was only the 16th wettest month, on the England & Wales Series, dating back to 1766 . Last month recorded 184.6mm, well short of the wettest month on record, October 1903, which had 218.1mm.
If you read the paper from the MetOffice you'll see that the frequency and intensity of events like this has changed as the planet has warmed, so even if an individual event like the recent British flooding could have occurred hundreds of years ago, it's more likely now.
I really don't see what the deal is with the floods. The flooded areas are built on the river Thames floodplain. You build your house on the floodplain of a major river and then wonder why your house floods? Must be global warming it couldn't possibly be bad planning.
It's constantly reported that the recent bad weather is a result of global warming.
But if you watch a weather forecast on the TV for eg, the weather person will often say something like this....
"This is the worst weather/rain/wind we have seen in 200 years."
So I'm wondering. How can the recent weather have anything to do with global warming if we experienced worse weather than this 200 years ago??
