If you get the feeling that big storms are arriving more frequently than in the past you are probably correct. Powerful storms that used to arrive only once every 30 years or so are now arriving three times as frequently, according to a Cork engineer.
"This is not model prediction, it is based on actual measurements," stated Prof Ger Kiely, professor of civil and environmental engineering at University College Cork. "This has fierce implications for the engineering community."
Prof Kiely has studied climate change and flooding and decided to do a detailed analysis of both rainfall and river flow measurements taken over the past six decades. "What I have been trying to do is study climate change by using measurements on the ground."
Eireann's main recording stations and at Aldergrove in Northern Ireland.
River measurements are based on data from automated height meters. A detailed study of flow versus height is done periodically so that a height reading can also indicate the water volume.
"I took rainfall records and river records and worked them up," Prof Kiely explained. "I recognised there was a blip in the records in the period between 1970 and 1975."
This led him to split the data into halves, pre-1975 and post1975. This allowed a remarkable set of findings to emerge.
He found that we get more rain now than in the period between 1940 and 1975. For example the annual Valencia station rainfall pre-1975 is 1,370 mm, compared with 1,520 mm post-1975.
"It is up by 10 or 11 per cent. You see two different sets of data," Prof Kiely said. He found this to be true for all recording stations.
He next looked at monthly rainfall records, again using the two time series pre- and post-1975. "The increase that we got seems to be concentrated in two months of the year, in March and in October/November. There is no change in the summer."
Met Eireann's hourly data was next examined. Prof Kiely wanted to see what change there was in the "intensity" or rate of fall of the rain. Increased rainfall could either be associated with higher intensity or just longer periods when the rain was falling.
"There is no increase in the intensity of the rainfall but the number of wet hours has gone up. This seems to be the general pattern principally in the west coast stations but to a lesser extent in the east."
Prof Kiely linked the change to the "North Atlantic Oscillation", an association between low pressure over Iceland and high pressure over the Azores further south. "We have all heard of El Nino and the European equivalent is the North Atlantic Oscillation."
A perfect balance between the pressure cells gives an oscillation index of zero but this balance is never maintained over time. "When the index is below zero we tend to get dryer colder periods. When the index goes above zero we get milder, wetter weather," he explained.
No prizes for guessing where we are at the moment. The index was negative pre-1975 but has been positive since then. "Physically what it means is we are getting more wet conditions than we would if the index was negative."
His most startling findings relate to the arrival of storms and their increasing frequency.
His intensity analysis of storms since 1940 has shown that they dump more rain on us. Looking at Valencia again, the pre-1975 intensity gave an average rainfall of 95 mm per storm. Since 1975 this has increased to an average 128 mm per storm, a 35 per cent increase.
He then plotted a curve to assess how the return period of given storm types - how often a storm of a given strength arrives - was changing. His findings have important implications for all of us. What used in the pre1975 period to be considered a "30-year storm" - one so strong that we might only see its like once every three decades - can now be expected once every 10 years in the post-1975 scenario.
His calculations are still underway for other rare weather events, the 50- and 100-year storms, but he expects the frequency of all of these to increase.
Climate predictions arising from research elsewhere have suggested that northern Europe generally will be warmer, but will receive heavier rain and more frequent powerful storms. Prof Kiely might have at least some evidence to prove those predictions.