UK must prepare for more intense storms, climate scientists say

Britain must brace for more storms like Dennis and Ciara because rainfall will be more intense in a climate-disrupted future, scientists have warned.

They said the government needed to increase the creation of more natural drainage systems if it wanted to avoid having to raise the level of sea and river defences every few years to counter the growing threat of flooding and storm surges.

Storm Dennis killed at least three people and flooded many parts of the country at the weekend. Politicians from all parties have acknowledged the link to the climate crisis, but differ over how to respond.

The new environment secretary, George Eustice, said on Sunday that the UK was already spending billions of pounds on flood infrastructure, but that there was a limit to how effective this could be in the face of a worsening threat.

“We’ll never be able to protect every single household just because of the nature of climate change and the fact that these weather events are becoming more extreme,” he said, “but we’ve done everything that we can do with a significant sum of money, and there’s more to come.”

The shadow environment secretary, Luke Pollard, has called for a new strategy, saying the government is not doing enough to respond to the crisis.

England has experienced a major flood almost every year since 2007, leaving about 100,000 properties damaged, according to scientists in the Climate Coalition.

They said the risks were amplified by human-driven global heating because a warmer atmosphere was able to absorb more moisture. This can then be dumped in shorter periods of time, as happened at the weekend, when parts of the UK experienced a month’s rainfall in two days.

Dr Marc Stutter, a senior scientist at the James Hutton Institute in Aberdeen, said: “Such storms are part of a shifting baseline for the climate and the state of the landscape on which the rain falls. While future scenarios for rainfall and runoff are highly uncertain, there is less doubt that the future has greater variability in extremes of rainfall, both in terms of flood and droughts.”

Stutter said the problems were worsened by the degradation and concreting over of natural buffers, such as soil and green spaces. “Infiltration and places to slow, store and filter water need to be planned back into landscapes to add resilience to floodwalls; the alternative is we risk raising the walls every few years.”

Dr Mohammad Heidarzadeh, the head of coastal engineering and resilience at Brunel University, said the UK’s flood defences were not suited to the current situation, which is characterised by high frequency and high intensity climate events.

“While the interval for major floods was 15-20 years in the past century in the UK, it has dramatically shortened to two-to-five years in the past decade. Therefore, it is no surprise that several flood defence systems were overtopped or damaged by flood water,” he said.

Heidarzadeh said the solution was not just to pour more concrete into barriers and channels, which can sometimes make the situation worse. Instead, soft-engineering solutions were just as important.

“Non-structural solutions, such as managed retreat, sustainable drainage systems and public involvement, are vital. The country needs further investment in its flood systems, but such investment should be within a holistic and integrated framework.”

After Storm Desmond devastated parts of Scotland, the Lake District and Northern Ireland in 2015, scientists estimated human-driven change to the climate made extreme rain about 40% more probable. Similar attribution studies for the latest downpours will need more time, but the overall trends towards more extreme weather are well established.

Compared with 50 years ago, the Met Office says the maximum daily deluge each year has risen by 17% from 64mm to 75mm, while the longest wet spell has increased from an average of 12.4 days to 12.9 days.