A forecast of things to come? The most talked-about topic among Irish people is the weather, and the unseasonable weather of late has had us all in chattering overdrive. But is the current weather an aberration or is it a sign of things to come? Anton McNulty investigates Anton McNulty IN the two weeks that followed Christmas, motorists re-enacted the same routine every morning. Get a jug of warm water and pour it on the windows of the car to clear a layer of glistening frost. While this practice is not alien to Mayo motorists, the length of this cold snap and its severity came as a surprise to many.
At this time of year we are more used to getting battered by the Atlantic winds and we generally associate heavy frosts with the midlands. The average temperature in 2009, by late last week, was just three degrees Celsius, as recorded at the Belmullet Met station. The rainfall for December was down on average and so far this year only 0.3 mm of rainfall was recorded in Belmullet when the average rainfall in Belmullet for the month of January is normally 123.7 mm.
In contrast, we had a wet summer last year with statistics issued from Met Éireann showing that the summer rainfall was well above normal, and the average temperature was also above normal. In Belmullet during the month of August, the rainfall was 192.3mm when the average for that area is usually 93.5mm.
These extreme and unusual changes have led some people to ask what is happening to our weather system? Some believe it is a result of global warming and these unpredictable weather patterns are a sign of what to expect in the future. However, Professor Ray Bates, who is the adjunct Professor of Meteorology at UCD and a contributor to the UN Intergovernmental Panel on Climate Change report, explained that while global warming is occurring, what we are currently experiencing is a result of the natural variability of our Atlantic climate.
“This hasn’t happened for some time, but looking over the longer term it is not unusual to have winters like this. There is a lot of natural variability in the climate systems and some people have felt that because we haven’t had as many frosty nights in recent years, it was due to global warming. It [global warming] is real and happening but at the moment the natural variability of the climate at our location is more important in determining the changes from season to season than the signal of global warming. Over the next couple of decades, natural variability will still predominate in determining between one year and the next, and even if you get a rise in the global temperature, you will get cold cold winters,” he explained.
Over the past century the average rise in temperature has been 0.7 degrees, but climate scientists expect that if the greenhouse gas emissions continue unabated the temperature will rise by another two or three degrees. The predicted climate models for Ireland which will result from global warming are for warmer and drier summers and wetter winters. At first glance, the unusually cold winter and and last year’s wet summer appear to fly in the face of what is predicted, but Professor Bates feels that these changes will occur over decades rather than year years.
“You could get people who are deniers of global warming saying ‘look, we have a cold winter and that global warming is all codology’. Global warming is real and we have to worry about it even if we get a cold winter or a wet summer. Some models predict we will get significant decreases in summer rainfall and we will have to worry about our water resources in the future. In our climate we will always have a fair amount of rain and I think the climate change would have to have progressed quite far before we would become really aware of serious rainfall deficiencies in Ireland.
“I’m not a hyper-alarmist – there are voices saying this will be an immediate disaster, but I’m saying it is a serious long-term threat. I wouldn’t say that over the next number of decades we have to worry too much about it. I would say the biggest worry of all at the moment is the sea level rise, which in the long term will be a serious threat,” he warned.
’08 was the wettest year on record at Straide Climate Station
Martin Sweeney THE year 2008 was the wettest year on record at Straide Climate Station since I first started monitoring there in 1963. Rain fell on 264 days and the total fall was 1,505.5mm (59.27 inches), making it the wettest year in 45 years. The wettest day was on October 9 when a rainfall of 37.8mm (1.5in) was recorded at Straide.
A feature of the year’s rainfall was the intense falls over short periods. On May 31, a thunderstorm dumped one inch of rain in 30 minutes. This was a rare fall as an inch of rain represents a very wet day’s fall.
During the months of August, September, October and November, there were falls of three to four inches in a week which is more or less a month’s rainfall in seven days. On August 13, four inches of rain fell in 24 hours at the Met Éireann Climate Station in Belderrig on the north Mayo coast.
On July 31, four inches of rainfall was also recorded on the hills south of Newcastle West in County Limerick and a flash flood of six feet from the local river swept everything that was on the main street in Newcastle West. Fortunately, no lives were lost.
During the summer and autumn, there were a few brief high pressure interludes with some pleasant weather. May was a pleasant month with 207 hours of sunshine with the temperatures over 21C on eight days. By May 30, only 13mm of rain had fallen. However, on May 31, 25.5mm fell in a brief thunderstorm.
With ten days remaining in December and with the figure standing at 59.27 inches, it looked odds-on that the 60-inch mark would be surpassed for the first time since I started the station in Straide 45 years ago. However, high pressure became established over the entire region and across Britain with dry cold settled weather and no rain fell from the December 22 to the end of the year.
I have, courtesy of Met Éireann, annual rainfall data from two neighbouring stations within a ten-mile radius and spanning over 100 years. These are from The Rectory in Castlebar (1900 to 1942) and the Ballyvary Garda Station from 1943 to 1962, as well as Straide Climate Station from 1963 to 2008.
All three stations are in more or less flat open countryside with no adjacent mountains to increase the rainfall. However, Castlebar is only a few miles from the Nephin mountain range where there is a high annual rainfall and the annual rainfall for Castlebar is three to four inches higher than in the Straide-Ballyvary area.
Moving back in time in reverse order, I find that during the 45-year period from 2008-1963, Straide has not recorded a 60-inch annual rainfall, the nearest being 59.27 in the year just ended, and the driest over that same period was 34.98inches in 1971. From 1962 back to 1943, Ballyvary did not record a 60-inch rainfall either, the heaviest being 59.81 in 1954 and the driest at 40.31 in 1952.
However, in the timeframe from 1942 back to 1900, Castlebar did record four years in which the rainfall surpassed the 60-inch mark. Those were in 1938 (61.95), 1931 (62.54), 1928 (63.66) and 1903 (60.74). The driest year over the same period as in 1905 (38.19).
Before I close, I return to 2008. The air temperatures ranged from a low of -7.4C on January 6 to a high of 24.7c on July 24. The sunniest day of the year was on May 14 with 13.8 hours. There were three snowfalls in January, February and March with a total depth of 15cm. Thunder was heard on 14 days.
Martin Sweeney has operated the Straide Climate Station for Met Eireann since 1943. Now a retired postman, Martin faithfully chronicles all matters relating to the weather on a daily basis.
