First, the “non-trend”. I am reproducing here an article in full from http://www.notalotofpeopleknowthat.wordpress.com. (I rarely do this, but for the purpose of having all information here for discussion, I did so.) Please visit the blog for more interesting articles on US precipitation, and other climate change topics.
UK Precipitation Trends
By Paul Homewood
The Norwegian Meteorological Institute, in conjunction with The European Academies Science Advisory Council (EASAC), have published a report, “Extreme Weather Events in Europe: preparing for climate change adaptation”, which makes the usual claims that extreme weather events are on the increase.
One of their claims concerns winter rainfall:
Winter rainfall has decreased over Southern Europe and the Middle East, and has increased further north. The latter increase is caused by a pole-ward shift of the North Atlantic storm track and a weakening of the Mediterranean storm track. Short and isolated rain events have been regrouped into prolonged wet spells.
But have we seen this effect in the UK?
Winter rainfall has increased since the 1960’s, but only back to levels seen earlier in the 20thC. Even further north in Scotland, the pattern is similar.
Professor Stuart Lane of Durham University has looked at long term precipitation records for the UK, and concludes that the period from the 1960’s to the 1990’s was an unusually dry one, so there is nothing to suggest that current levels of rainfall are in any way unusual. (Remember that this period coincides with the cold phase of the AMO, that leads to drier conditions in the UK – see here.)
Let’s finish by looking at rainfall intensity, which the EASAC paper suggests is getting worse.
As with overall rainfall totals, we see an increase in the average rainfall per rainday since the 1960’s, but no increase at all in the last 20 years. Indeed, if anything there is a decline. We also see the same sort of pattern with the number of raindays. (Met Office data for raindays only starts in 1961)
I can make no comment about the rest of Europe, but it is clear that the report’s findings on this particular topic have no factual basis in the UK.
All data from the UK Met Office