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It's raining, it's pouring - but why?

You could hear the curses from news desks across the country at 11.00 this morning. The Met Office had just released its figures for 2012 and it was not the wettest year on record. Bother!

But hang on, it was the second wettest, with 52.3 inches of rain, and missed the top spot by only a quarter of an inch. What is more, the Met Office put out the results of an analysis, albeit preliminary, showing that it does seem to be getting wetter.

People shelter from the rain at a bus stop at Heather, Leicestershire in July Credit: Rui Vieira/PA Wire

For example, out of the top five wettest years (including last year), FOUR were in the last 12 years.

And when the Met Office looked at rainfall averaged over thirty year periods, a depressing trend emerged.

Floods in Oxfordshire in November Credit: Steve Parsons/PA Wire

In the 60s, 70s and 80s, average rainfall was 43.3 inches.

In the 70s, 80s and 90s, it was over 44 inches and in the 80s, 90s and 00s, it was over 45 inches.

An upward trend - an overall increase of about 5%.

Not only that, the figures also show the kind of rain we're getting is changing: there are more and more "extreme" days of rainfall - one reason for all the floods.

Sheltering from the rain in August Credit: Lewis Whyld/PA Wire

Why is all this happening? According to Julia Slingo, Chief Scientist at the Met Office, we do not know for sure.

Changes in the temperature of the sea surface due to natural cycles may be one factor. And two of the other possibilities she mentions are linked to global warming.

First, the loss of sea ice in the Arctic, which has been linked to heavier rainfall, and secondly, increasing global temperatures - the warmer the temperature of the air, the more moisture it can hold and so the heavier the rainfall.

None of this is conclusive - we can not say for sure that global warming is causing heavier rainfall and floods. But it is looking more and more likely that it is at least one factor.

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