Analysis: New research finds science for Ireland is now clear: human-driven climate change is discernible in Irish weather records
It seems that news about our changing climate is never out of the headlines; from Canadian wildfires to floods across Europe and in Ireland, our weather is changing and wreaking havoc across the planet. While scientists and international bodies, like the Intergovernmental Panel on Climate Change, have been warning about these events for decades, it's taken disasters to create action. Even then there are still people who deny the science, many on the grounds that they don’t believe the changes are due to human actions.
Discerning a human driven (or anthropogenic) climate change signal in observed weather records is important for this reason and also to identify impacts of climate change that require adaptation. Many previous research papers have examined trends in Irish weather records, but none have sought to attribute observed changes to anthropogenic climate change.
At a planetary scale, Global Mean Surface Temperature (GMST) is often used to track changes in climate and to inform international policy. For example, the Paris Agreement aims to limit GMST increases to no more than 2oC above pre-industrial to avoid dangerous climate change. GMST is a powerful representation of human driven climate change, with all warming in GMST attributable to human activity. However, GMST is not directly experienced by everyone on the planet in the same way. Rather, regional and local changes in climate and variability affect people's day to day experience, especially in mid-latitude regions like Ireland.
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From RTÉ Radio 1's Morning Ireland, will events like Storm Babet become more and more common with climate change?
New research funded by the EPA and Met Éireann as part of the HydroDARE project set out to see if an anthropogenic climate change signal is discernible in Irish weather observations. Until now it was thought that Irish climate was just too variable to detect a clear anthropogenic climate change signal at this point in time.
Working with students on the MSc Climate Change at Maynooth University, together with researchers at Maynooth and Met Éireann, we compiled temperature and rainfall records available in Ireland, some dating back to 1850. We then linked changes in local temperature and rainfall records to global temperature changes. Using statistics, we quantified how much the Irish climate has changed since early industrial conditions when natural climate variability dominated, as being 'unusual' or ‘unfamiliar’ relative to that benchmark.
We found that annual mean temperature shows the largest signal of human driven climate change of any variable considered. The Island of Ireland shows a rate of warming of approximately 0.88oC per 1 degree increase in GMST, which we consider ‘unfamiliar’ relative to early industrial climate. Five weather stations in eastern and central regions show a rate of warming greater than GMST, with an increase of 1.14oC per degree of warming in GMST found at Phoenix Park and in excess of 1oC at Armagh, Birr, Dublin and Glasnevin.
When we looked at temperature extremes, cool days and nights and warm nights, we found the emergence of 'unfamiliar' conditions relative to the natural baseline.
In the case of the rainfall data, fewer stations and indicators show the emergence of a clear climate change signal due to the large variability in rainfall data from year to year and season to season. However, many stations show substantial increases in winter rainfall per degree warming of GMST, indicating considerable increases in flood risk, even if future global temperature is restricted to 2oC as called for under the Paris Agreement.
One third of the 30 rainfall stations analysed also show increases in rainfall intensity (the heavy rainfall that often causes surface flooding, especially in urban areas) and are considered 'unusual' relative to early industrial climate. On average, rainfall intensity in Ireland is increasing at a rate of 8.2% per degree of global warming.
Read more: What does climate change mean for Irish rivers?
The science for Ireland is now clear: human driven climate change is now discernible in Irish weather records. Of the 903 climate indicators we analysed across the study, 37% show the emergence of conditions we would consider at least ‘unusual’ relative to early industrial or natural climate.
These results clearly tell us that adaptation to the impacts of climate change needs to be given greater emphasis in national and local climate policy. Climate change is here, and it is evident in our weather observations.
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
