The rainfall that came with Storm Claudia was 12pc more intense because of human-caused climate change, new research has found.
A new report from Maynooth University and Met Éireann has found that human-caused climate change increased the likelihood and intensity of the heavy rainfall that came with Storm Claudia earlier this month.
September and October were unusually wet months in Ireland this year. Then November arrived and brought with it Storm Claudia, causing heavy rainfall and flooding, particularly in the south-east.
“The science now confirms that when these rainfall events occur, they will bring more rain than in the past because a warmer atmosphere can hold more moisture. This is one of the consequences of living in a warmer world,” said Met Éireann climatologist Paul Moore.
In a rapid attribution study, the research team looked at recorded rainfall for two days of the storm – Friday 14 and Saturday 15 November – in Dublin, Wexford and Wicklow.
They found that the intensity of the rainfall increased by 12pc when compared to a pre-industrial (1850-1900) climate.
The global climate is today about 1.3 degrees Celsius hotter than pre-industrial levels. With further warming, the team predicts that similar rainfall events will increase in intensity – as much as 8pc with 3 degrees Celsius of warming.
The researchers also examined 30 days of rainfall conditions before the storm in counties Dublin, Carlow, Kildare, Kilkenny, Laois, Louth, Meath, Wexford and Wicklow.
They found that when compared to a pre-industrial climate, the intensity of rainfall in these counties was increased by nearly 7pc. With further warming, the team predicts that similar rainfall events will increase in intensity – 4.5pc with 3 degrees Celsius of warming.
‘Twice as likely’
Both the two-day heavy rainfall event and the 30 days of rainfall prior to it have become twice as likely because of the climate crisis.
With 3 degrees Celsius of global heating, the researchers expect a similar two-day rainfall event to happen once every one to two years and similar 30-day rainfall events to happen once every two years.
“While the potential threats from the two-day rainfall event in the south-east were well communicated to the public, flood defences were seriously tested,” said Maynooth University’s Dr Claire Bergin.
“This is especially concerning when 30-day rainfall levels are also rising. It increases the likelihood that soils will be saturated and rivers full when heavy rain arrives. A global effort is needed to reduce emissions and limit the effects of warming for everyone.”
Lionel Swan, a PhD researcher who worked on the study, said that Ireland has been lucky in recent years because extreme weather events have occurred at times of low or moderate tides.
“The Midleton flooding of 2023, Storm Éowyn in January and Storm Amy in October of this year all coincided with either a neap tide or with a spring low tide,” he said.
“These tidal conditions allowed water from our rivers to essentially escape to the ocean, reducing the severity of flooding. This again was the case with Storm Claudia, where the heaviest rainfall occurred in the days that followed a neap tide.
‘The worry is that our luck will run out’
“The worry is that our luck will run out eventually, we will experience an extreme event that coincides with a spring high tide, and the resulting impacts for flooding are likely to be far worse than we’ve experienced before.”
Maynooth University’s Prof Conor Murphy said the signal is clear – “[c]limate change is increasing the likelihood and severity of flood events”. He called for investment in local adaptation measured to protect communities from future extreme weather events.
This rapid high-temperature attribution analysis was carried out under the WASITUS (Weather attribution science Irish operational user service) project at Maynooth University’s Icarus Climate Research Centre and funded by Met Éireann and the EPA.
In September, the team released a rapid attribution analysis which found that the night-time temperatures that made summer 2025 the hottest on record in Ireland were 40 times more likely because of human-caused climate change.
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