Flooding has hit towns and rural communities across England and Wales.

Storm Dennis has been blamed for the flooding, although it came hot on the heels of Storm Ciara a week before and follows months of wetter-than-average weather, with the ground becoming progressively saturated.

Some of the areas worst affected were hit by storms Desmond and Eva in 2015 and the flooding seen across the UK in the winter of 2013/14.

British winters have always brought spells of bad weather, but have they got worse in recent years? And is climate change to blame?

Here’s what we know and what we don’t know.

It’s been getting warmer

In the latest annual State of the UK Climate report, the Met Office said 2018 was warmer than any year from 1884 to 2002.

The top 10 warmest years in the UK have all occurred since 2002.

According to the Met Office, the Central England Temperature dataset – the longest-running instrumental record of temperature in the world – shows that 2009-2018 was around 1 °C warmer than 1850-1900.

That means more rain

Higher temperatures mean more water evaporates in the air to fall as rain again.

Dr Michael Byrne, lecturer in climate science at the University of St Andrews and research fellow at the University of Oxford, said: “These storms are nothing new, going back 100 years, but, because we are now more than 1C warmer as a whole versus pre-industrial times, every degree means 7 per cent more water in the atmosphere and more rain in these heavy rain events.

“When they come, they bring more rain, 100 per cent for certain, because of climate change.”

Many other climate scientists have echoed that sentiment, agreeing that there are likely to be more episodes of extreme rainfall in the future thanks to changes in global temperature.

Dr Ivan Haigh from the University of Southampton told FactCheck: “Climate change is making the likelihood of these events happening much more common, and I think we are seeing this all over the world.”

Sea levels are rising too

There is no serious dispute among scientists that sea levels are rising too, potentially increasing the risk of coastal flooding.

Satellite instruments called altimeters and tide gauges suggest the oceans are rising and that the rate is accelerating. NASA says the seas have risen by an average of nearly 3 inches since 1992.

Again, there is a clear link between rising global temperature and rising sea levels: water expands when you heat it, and ice sheets and glaciers that previously stored water melt more quickly.


While there is no doubt about the underlying science, experts say there is considerable uncertainty about the precise effect of climate change on British weather – we can’t say for sure how the strength of storm winds or patterns of rainfall will change.

And it’s hard to attribute one individual weather event like Storm Dennis directly to climate change.

Historical data about flooding is also often incomplete and hard to interpret, so it’s difficult to say for sure that floods have become more frequent or severe.

The UN’s Intergovernmental Panel on Climate Change states cautiously that there is “low confidence (due to limited evidence)” that man-made climate change has made floods more common or more extreme.

But the IPCC says climate change “has detectably influenced several components of the hydrological cycle such as precipitation and snowmelt (medium confidence to high confidence), which may impact flood trends”.

The panel adds: “Projected precipitation and temperature changes imply possible changes in floods, although overall there is low confidence in projections of changes in fluvial floods.”

UK public bodies are bolder in their warnings about the effects of climate change.

The Environment Agency’s official flood risk management advice is to prepare for significant rises in the intensity of rainfall, the peak flow of rivers and sea levels around the UK over the next century.

The agency admits that “given the complexity of the science around climatic projections, there are significant uncertainties attributed to the climate change allowances”.

Human factors

One reason the IPCC gives for lack of evidence on a link between man-made climate change and flooding is that human activity affects the way water behaves after it falls.

Urbanisation on flood plains and coastal areas, dams, raised riverbanks and other flood defences can all affect the risk of flooding.

This means that if you just measure flooding by the impact it has on people, that may not tell you much about climate change.

Dr Haigh told us: “Although sea levels are rising, the number of incidents of coastal flooding has actually fallen, for a number of reasons. The Met Office have got better at predicting floods and the flood defences have improved.”

Many scientists quoted today have stressed the importance of land use and engineering in managing flooding, and are calling for more action to cope with potentially worse floods.

FactCheck verdict

There is no disagreement among serious climate scientists: global warming leads to more rain and rising sea levels. That means Britain could see more extreme weather and more flooding in the future.

There is some uncertainty around how exactly the weather could change, and about the historical evidence for a link between climate change and flooding.

The official advice used by the British government predicts that rainfall, rivers and seas will continue to rise in the coming decades.