July’s record-breaking dry spell may not be repeated soon, but Ireland could regularly find itself in summer drought even if more rain falls, scientists have found.
The team from Maynooth University say heightened evaporation caused by warming temperatures is likely to cancel out summer showers, leaving the ground just as parched as if the rain never fell.
They say extreme evaporation in an Irish summer is eight times more likely to occur because of climate change and that its strength has increased by 7 per cent.
Claire Bergin of the Icarus Climate Research Centre at Maynooth University said the findings were significant for anyone who relied on the land or was responsible for its management.
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“This July was very, very dry but on top of that there was a lot of evaporation,” she said.
In future, July might be wetter, but an increase in evaporation would be evident, she added.
“So even if there’s a bit more rain, you’re still going to be struggling with the evaporation happening at the same time. Farmers or people looking at fire management are going to have to be aware that there will be this extra drying condition.”
Bergin and her colleagues run the Wasitus project, part of the World Weather Attribution network of scientists who conduct rapid analysis on recent weather events to understand what role climate change played.
“We can’t really confidently link the lack of rainfall conditions with climate change, but we can link this evaporation,” she said.
It was driven by the heatwave in July, which was the hottest month on record in Ireland.
“Observations suggest that the maximum temperatures experienced this summer have become 40 times more likely as a result of climate change,” notes the Wasitus report.
Without human-caused climate change accelerating the heating of the planet, such exceptional summer heat might be expected once in 400 years, but it was now likely every 10.
The report also found the high night-time temperatures throughout the summer “were practically impossible without climate change”.
July barely had any rain, with just 16.1mm recorded over the entire month – a sixth of the average rainfall for the month recorded in the 30 years to 2020.
The report says there are uncertainties as to how wet future Julys will be – with some climate change models suggesting they may be more likely to be slightly wetter.
But with increasing heat and evaporation, those vital rainfalls will not hydrate soils, crops and vegetation so efficiently.
“What historically has been seen as unusually dry soil conditions will become increasingly common under further global warming,” the report says.
“It is important that farmers start to plan for such an eventuality rather than seeing the past summer as a one-off.”
