Storm Eunice: Was climate change responsible?

The Met Office has issued a Red Weather Warning due to storm Eunice, which is hitting the south of England and Wales and bringing extremely strong winds, rainfall and flooding.

Exposed coastal areas are to see the worst gusts from the extreme weather event, with a wind speed of 196kph (122mph) recorded on the Isle of Wight this morning, Friday 18 February 2022.

Eunice's impact on the sea level could cause storm surges, and severe flood warnings have been issued for parts of the country including the Severn Estuary and River Wye in Gloucestershire. In Devon and Cornwall, power cuts have affected more than 50,000 homes, and the BBC reports that Ireland has 73,000 homes and businesses without power.

BBC Weather said Eunice "could well be one of the worst storms in three decades".

The storm follows just two days behind another, storm Dudley, which battered Scotland and Northern Ireland on 16 February.

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“After the impacts from storm Dudley for many on Wednesday, storm Eunice will bring damaging gusts in what could be one of the most impactful storms to affect southern and central parts of the UK for a few years," said the chief meteorologist at the Met Office, Paul Gundersen.

“The red warning areas indicate a significant danger to life as extremely strong winds provide the potential for damage to structures and flying debris."

Some scientists have suggested that the impact of storm Eunice – and future storms – has been exacerbated by the climate crisis. But how exactly does rising temperatures affect the UK weather?

Has climate change caused Storm Eunice?

"Quite often the question posed is whether an event is because of climate change or not. But it's just not a yes or no question," saidDr Friederike Otto, a lecturer at the Grantham Institute for Climate Change, Imperial College London.

"Climate change can be one of the causes, and it can make events worse. But it is never the only cause."

In the case of storm Eunice, the high-speed winds are unlikely to have been caused by climate change. But, according to Otto, the damage done to the UK shores will have been made worse by the rising temperatures.

"What we do know is that the rainfall and storm surge aspects of these storms is worse because of climate change."

Climate change could also push storms further up the globe, said Professor Dann Mitchell, a climate scientist at the University of Bristol.

"We do know that the positioning of these storms might change, and that's because of climate change's impact on the jet stream."

The jet stream is an air current that circles the Northern Hemisphere, distributing wind and rain, storms and heatwaves.It's thought that increasing air temperatures will alter the flow of the air, causing the jet stream to move further north.

"The jet stream controls the storm tracks, the way the storms travel over the North Atlantic and hit us [in the UK]. So, as climate change is causing a poleward shift in the jet stream, you'd expect a poleward shift in the storm tracks as well," said Mitchell.

"We're also expecting to see a deeper penetration of these storm tracks in Europe. So, while it's true to say that the wind itself is not detectably different [due to climate change] yet, in a sense storm winds will increase somewhere, because they're affecting places that they normally wouldn't."

How does climate change cause flooding?

Otto said increased rain is due to what is called the thermodynamic effect. "A warmer atmosphere can hold more water vapour and that water vapour needs to get out of the atmosphere, which it does as rainfall."

Currently, one degree of global warming results in a seven per cent increase of rainfall in these events. "It doesn't sound like much, but it's a lot," said Otto.

In addition, storm surges that bring water high above normal sea level are now even more dangerous. "Storm surges that usually occur with these events are more damaging, because sea levels are higher than they would have been without climate change," said Otto.

"As long as temperate global temperatures are rising – and they will not stop rising until we have reached net zero CO₂ emissions – these events [will get] more frequent and more intense. With the current trajectory of greenhouse gas emissions, we will see more flooding, more intense rainfall and many more hot and long heatwaves."

What can be done to protect the UK from the impacts of climate change?

"We have a lot of an agency in reducing our vulnerability [to these events]," said Otto. "Redesigning our cities so that there are more green spaces means that water can go somewhere. It doesn't necessarily have to flood the houses."

These actions can also help us as heatwaves become more common. "A lot of the things you need to do to be better protected from flooding are the same things that you need to be better protected from heatwaves.

"Green spaces are so important. On the one hand, water can go somewhere and it doesn't flood houses, but also when you have more green spaces the temperatures in the cities don't get so high."

As well as being dangerous to health, heatwaves can cause fires, as seen in February 2019 when temperatures broke records and caused outbreaks of fire in East Sussex, West Yorkshire and Edinburgh.

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For Mitchell, the question is whether the climate is changing faster than we are adapting.

"At the moment, the answer is almost definitely yes. We do have more things in place, like trying to avoid building on floodplains, because we know they're going to become worse in the winter. But in terms of the nationwide infrastructure, we need to do better."

Previous UK storms have damaged coastal infrastructure and affected rail networks, and these things are still a concern in the future, said Mitchell.