Global warming is having an effect on the timing of river floods in the UK and across Europe, research has shown.
In parts of northern Britain, western Ireland, coastal Scandinavia and northern Germany, floods were now tending to occur two weeks later than they did 20 years ago, said scientists.
A reverse pattern was seen in Sweden, Finland and the Baltic States, which were experiencing floods a month earlier than they did in the 1960s and 70s.
The research, published in the journal Science, is based on 50 years of data from more than 4,000 hydrometric stations in 38 countries.
Lead scientist Professor Guenter Bloeschl from TU Wien University in Vienna, Austria, said: "In the north-east of Europe, Sweden, Finland and the Baltic States, floods now tend to occur one month earlier than in the 1960s and 1970s.
"At that time, they typically occurred in April; today in March. This is because the snow melts earlier in the year than before, as a result of a warming climate."
Mark Maslin, Professor of Climatology at University College London, said: "Nearly every major city and town in Europe is built on a river and we protect this urban infrastructure by using past floods as a gauge of the potential risk.
"All the infrastructure that we have built to protect our cities needs to be reviewed as much of it will be inadequate to protect us from future climate change induced extreme flooding.
"In the UK a systematical check on our urban flood defences is required based on this new study to ensure the extensive damage of 2007 and 2010 floods are avoided."