Human-induced climate change detected in Irish weather records

Analysis: new research shows the science is now clear for Ireland; Human-induced climate change is evident in Ireland’s weather records

News of our changing climate never seems to leave the headlines. From wildfires in Canada to floods across Europe and 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, disasters are needed for action. Even then, there are still people who deny the science, many on the grounds that they don’t believe the changes are caused by human activity.

Detecting a signal of human-induced (or anthropogenic) climate change in the observed weather record is important for this reason, as well as identifying climate change impacts that require adaptation. Many previous studies have examined trends in Irish weather records, but none have attempted to attribute the observed changes to anthropogenic climate change.

On a planetary scale, Global Mean Surface Temperature (GMST) is often used to track climate change and inform international policy. For example, the Paris Agreement aims to limit GMST increases to no more than 2oC above pre-industrial levels to avoid dangerous climate change. The GMST is a powerful representation of human-induced climate change, with all warming in the GMST attributable to human activity. However, GMST is not perceived exactly the same way by everyone on the planet. Rather, regional and local changes in climate and variability affect people’s everyday experiences, particularly in mid-latitude regions such as Ireland.

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The new research, funded by the EPA and Met Ireland as part of the HydroDARE project, aims to determine whether an anthropogenic signal of climate change is detectable in Irish weather observations. Until now, Ireland’s climate was thought to be too variable to detect a clear anthropogenic climate change signal at this point in time.

Working with students MSc in Climate Change At the University of Maynooth, together with researchers from Maynooth and Met Ireland, we compiled the temperature and rainfall records available in Ireland, some dating back to 1850. We then linked changes in local temperature and precipitation records to changes in global temperature. Using statistics, we quantified the extent to which Ireland’s climate has changed since early industrial conditions, when natural climate variability dominated, as ‘unusual’ or unfamiliar compared to that standard.

We found that mean annual temperature provides the largest signal of human-induced climate change of any variable considered. The island of Ireland shows a warming rate of approximately 0.88oC per 1 degree increase in GMST, which we consider unfamiliar compared to the early industrial climate. Five weather stations in eastern and central regions show warming rates greater than GMST, with a GMST one degree warming increase of 1.14oC found at Phoenix Park and more than 1oC in Armagh, Birr , in 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.

For rainfall data, fewer stations and indicators show the emergence of a clear climate change signal due to high variability in rainfall data from year to year and season to season. However, many stations show a significant increase in winter precipitation for one degree of GMST warming, indicating a significant increase in flood risk even if future global temperatures are limited to 2oC as required by the Paris Agreement.

A third of the 30 rain stations analyzed also show an increase in rainfall intensity (heavy rainfall that often causes surface flooding, especially in urban areas) and are considered “unusual” compared to the early industrial climate. On average, rainfall intensity in Ireland increases at a rate of 8.2% per degree of global warming.

For Ireland, the science is now clear. human-induced climate change is now detectable in Ireland’s weather records. Of the 903 climate indicators we analyzed in the study, 37% indicate the occurrence of conditions that we would consider at least unusual compared to early industrial or natural climates.

These results clearly tell us that adaptation to the impacts of climate change needs to be given greater emphasis in national and local climate policies. Climate change is here, and it’s evident in our weather observations.

The views expressed here are those of the author and do not represent or reflect the views of RT