It has been the wettest summer for almost half a century and indicators suggest Ireland is getting a taste of what climate change is about, writes John Sweeney.
As August nears its end most people will remember summer 2007 as one of the worst on record in Ireland. It was an exceptionally wet summer, with approximately 350mm of rainfall recorded along most of the east and southeast of the country from June-August. It was the wettest summer here in almost half a century.
To find a wetter summer it is necessary to go back to 1958 when almost 420mm was measured at Dublin airport. In more recent times, only the washout of 1985 with 310mm came close.
In 2007, Dublin experienced a total rainfall for the months of June, July and August almost identical to that received in the entire year of 1887.
Cork fared little better, having had the dubious pleasure of a June total rainfall this year which was over 10 times that received in the comparable period last year.
Indeed, for the summer as a whole, the east fared worse than the west with typically twice the average rainfall at most locations.
Although not without its quota of wet days, the west and northwest fared slightly better. Malin Head and Belmullet had less than 75 per cent of the rainfall that the east coast experienced - an unusual turn of events in an island normally characterised by an east coast lying in the rainshadow of a wetter west.
Indeed, July was the sunniest July in the extreme northwest for over half a century. Despite the gloomy skies and rain, however, temperatures were not as poor as might have been perceived. Most locations away from the east and southeast managed to record temperatures close to the 1961-90 average values.
The west coast, for example, was over one degree warmer than this long-term average for the summer months, while even a wet Cork airport managed to struggle up to average temperatures.
That such warmth could exist even amid such a miserable summer illustrates, perhaps, that Irish temperatures are moving according to a global dictate.
From earlier monitoring of our weather, the Irish Claims Analysis Research Units (Icarus) for the Environmental Protection Agency in 2002, it is clear that global warming has been having an impact on Irish weather.
Almost all Irish stations now show increases in annual and seasonal temperatures matching, albeit with a lag of several years, the trends in global temperature.
Since 1890 temperature increases at the Irish weather station network have averaged 0.7 degrees, almost identical to the global value quoted in the latest report of the United Nations Intergovernmental Panel on Climate Change.
Like much of the rest of the world this warming has been most prominent in two periods, in the case of Ireland from 1910-1949 and from the 1980s onwards.
Since the 1980s, temperatures in Ireland have been increasing by 0.42 degrees per decade - significantly faster than the global average. Small wonder that six of the 10 warmest years in the Irish records have occurred since 1995.
Much of these changes have occurred in winters which have become noticeably milder.
Shannon airport, for example, has now over 32 days less frost in an average year than in the 1950s.
We have not, however, as yet had significant changes in the frequency of very hot days.
Summer nights have warmed faster than summer days, though no significant trend in summer heatwave frequency was detected.
It is, however, rainfall changes which will be most significant in the future for Ireland, as summers like 2007 become rarities and winters like the 2007 summer become commoner.
Overall, the records suggest relatively weak trends in rainfall as yet, but hint at increases in the west, especially in winter. Malin Head, for example, shows an average increase of 300mm on its annual total over the century from 1890-1990, while Valentia is over 18 per cent wetter since the 1960s. A rather weak trend towards drier summers in the southeast is also apparent.
These trends are roughly in line with what global climate models suggest for the future Irish climate. Wetter winters, especially in the west, and drier summers, especially in the east, are the principal message coming from such work.
In that context, of course, the summer of 2007 stands out as an anomaly. But the future, just like the past, will always have anomalous seasons and it is only by such a long- term view as this report provides that the overall context of change can be determined.
For those who believe that summer 2007 negated global warming concerns, however, there is one further important point to make. Everyone will remember the intensity of rainfall during the height of the summer months which brought such flood problems to Belfast in June, Dublin in July and, on a grander scale, to England in the same month.
Changes in extremes, especially of rainfall, can be expected to be one of the signatures of global warming as warmer ocean and land combine to produce instability in water vapour laden air masses.
While the jury is still out on many other areas, a picture is emerging of an Ireland following the path projected by global climate models and we may yet look back on summer 2007 as one where natural forces and anthropogenic influences on climate combined to produce a maverick summer which we may wait a long time for a repetition of.
Prof John Sweeney works with the Department of Geography in NUI Maynooth. He is director of Icarus as well as being a contributing author of a chapter of the Intergovernmental Panel on Climate Change's reports and review editor on another chapter