Met Éireann has told its forecasters that Ireland needed to prepare itself for much heavier rainfall, storm surges and coastal flooding, as well as the growing “likelihood of extreme weather events”.
The information was contained in a guidance note prepared within Met Éireann and issued to its forecasting division staff in June to help them communicate the climate crisis and its impact on Ireland. The advisory note was issued during a period of extreme weather events globally including record-breaking temperatures, catastrophic flooding and forest fires.
The Met Éireann guidance said it was “beyond doubt” that human influence had warmed the atmosphere, ocean, and land, and that temperatures here were up by approximately one degree Celsius since 1900. It said this made extreme weather events more likely, but that it was difficult to say how this would impact the frequency and intensity of storms in Ireland, with further research needed.
The advisory said Ireland’s climate had become significantly wetter, with annual rainfall in the 1991 to 2020 period 7 per cent higher than levels experienced between 1961 and 1990.
“Irish rainfall patterns are expected to change, with an increase in both dry periods and heavy rainfall events,” it said, adding that there was “high confidence” that maximum rainfall rates could be expected to increase as the warmer atmosphere would carry more moisture. The guidance said a warmer atmosphere could be expected to carry 7 per cent more moisture for every degree of warming, with heavy rainfall events inevitably increasing in intensity.
“Global sea level continues to rise. As a result storm surge and coastal flooding risk around Irish coasts is expected to increase,” it added.
On the heatwaves that have hit many different areas worldwide, the Met Éireann advisory said these were becoming more frequent and more intense, driven mainly by “human-caused climate change”. It said some of the most extreme heat events seen in recent years would have been very unlikely in the absence of human influence
The Met guidance said with changing rainfall patterns in Ireland there would likely be an increase in both extended dry periods and heavy rainfall events. “More severe agricultural and ecological droughts are projected under climate change; the more the planet warms, the more severe and widespread the drought impacts will be.”
On Irish sea surface temperatures (SST), it said changes there had been more unpredictable with periods of warming and cooling, but that marine buoy observation appeared to show climbing rates again. “Irish SSTs are currently well above average and North Atlantic SSTs are currently at record highs for this time of year, June 2023. NOAA [the National Oceanic and Atmospheric Administration] has declared an area of the Atlantic off the west coast of Ireland as a Marine Heatwave Watch area,” said the guidance.
The advisory said global sea levels had increased by approximately 20cm over the past 118 years, and that the pace of this was “accelerating”. It said sea levels in Ireland were broadly in line with global trends but that, worryingly, higher rates had recently been observed in both Cork and Dublin. The document said it was “unclear why” this was so, and that it was “currently under investigation”.
It said “key messages” based off recent data should be that 2022 was the warmest on record in Ireland, the 12th consecutive year with above normal temperatures in the country. The all-time highest maximum temperatures for July and August had both been broken at the Phoenix Park at 33 degrees, and in Oak Park, Carlow, at 31.7 degrees.
“Ten synoptic stations reported their highest daily maximum temperature, for any month, on record. Eleven synoptic stations broke their August maximum temperature record, with heatwaves reported at seven stations,” it added.