What’s behind those storms we have had recently?
Storms Dudley, Eunice and Franklin all landed in from the Atlantic over less than a week. They left a trail of destruction and chaos in Ireland and Britain, followed by severe flooding. With its "sting jet" pockets of great intensity, Eunice was the UK's worst storm in more than 30 years. A wind speed of 200km/h on the Isle of Wight was the highest gust ever recorded in England.
Their occurrence, however, is not unusual in the course of a winter.
But it feels as if storms are getting more frequent and more ferocious. Is this the case?
Not necessarily. There is huge natural variability; big storms arrive in the natural course of weather during winter. The debate is whether climate change and higher temperatures are making them more menacing due to higher wind speeds.
So is all this storm activity linked to climate breakdown?
It could be. As UK forecaster Michael Dukes of MetDesk has explained: "Although it is hard to pinpoint climate change as a reason for individual severe weather events, climate models do indicate an increase in these type of storms as Earth continues to slowly warm. So this is very much in line with what climate scientists have been warning us about for a number of years now."
What’s behind this more nuanced explanation?
While there is dispute between scientists over whether the storms themselves are likely to increase and become stronger, most agree the climate crisis will make their impacts worse.
Climatologist Friederike Otto leads the World Weather Attribution service. Asked whether big storms had been made more likely by climate disruption, she said there was "very little evidence that winds in these winter storms have gotten stronger with climate change".
Nevertheless, damage from winter storms has gotten worse because of human-caused climate change. This is for two reasons, she says.
Rainfall associated with winter storms has become more intense, and many studies link this clearly to climate change. Secondly, because of sea-level rise, storm surges are higher and thus more damaging than they would otherwise be.
Is Ireland increasingly vulnerable to winter storms?
Definitely, according to storms expert Prof Peter Thorne of Maynooth University. While science is unclear on whether we are in line for more frequent/ferocious storms, associated coastal storm surge and extreme rainfall impacts are more likely. With more intense rainfall and higher sea levels as human-caused climate change continues to heat the planet, flooding from storm surges and prolonged deluges will worsen further when rare, destructive storms like Eunice hit us in a warmer world.
What about the changing jet stream?
Evidence published this week shows that the north Atlantic jet stream, which circulates 10km above Earth’s surface, is moving northwards and increasing in speed. That is an added complication, as it influences storm activity and temperature patterns across the northern hemisphere.
This is because most storms come rolling in on the jet stream, which is more likely to be over Ireland – as it was recently. This long-term trend may be caused by climate change.
All told, the Atlantic will continue to throw up storms. The climate factor is likely to make for more turbulence, though in the form of sea surge and extreme flooding.
