The decade from 2006 to 2015 was Ireland’s wettest on record, with a 10-year average rainfall of almost 1990mm per year.
This compares with a long-term 300-year decadal average of 1080mm per year, and just 940mm in 1740-1749 – the driest decade on record.
These figures are according to a newly-developed 305-year record of rainfall for Ireland, compiled by Dr. Conor Murphy, senior lecturer in Geography at Maynooth University, and a team of national and international collaborators.
Commenting on the rainfall record, Dr. Murphy said: “The most recent decade was our wettest on record and, when we look at the long-term context, we see a continuous rise in annual and winter rainfall.
“This is consistent with expectations of human-driven climate change.”
Wetter winters and drier summers
While one of the most significant takeaways from the record is that Ireland’s weather was at its wettest between 2006 and 2015, the data also reveals that over the long-term winters are getting wetter and summers drier.
The lecturer explained: “The record draws on the very earliest rainfall observations made in this region, together with weather diaries compiled during the 1700s.”
“The task of stitching all the data together was first undertaken by UK Met Office staff in 1979 – work which was largely forgotten until recently. In those days there was not as much emphasis on publishing research in scientific journals and their work was just reported in an internal memo,” Dr. Murphy said.
From 1711 through to 2016
“We were able to merge that Met Office record with another, quality-assured dataset, which we recently compiled for Ireland for the period of 1850 to present. When combined, the derived record gives us an unprecedented picture of rainfall variations for every month from 1711 to 2016,” the lecturer noted.
Recent wet weather has had significant effects on Ireland; winter 2015/16 saw extensive flooding across Ireland, while winter 2013/14 was the stormiest on record.
“These winters which not only took place during our wettest decade, are also the first and second wettest individual winters on record.”
Practical uses
The rainfall series has a number of practical uses, which go beyond general interest in extreme weather events.
Dr. Murphy explains: “This record can be used to track changes in rainfall (both natural and driven by human activities).
The range of variability and the extreme events contained in our record also offer valuable information for stress testing critical infrastructure such as flood defences and water supply systems.
“This helps ensure that vital water services are resilient to future wet and dry periods in Ireland.”