Current investment in UK flood defences not enough to combat climate-related losses

Current levels of investment in the UK’s current flood defence infrastructure is not enough to combat climate-related losses from a severe flood event.

That was according to Moody’s RMS and Flood Re, which highlighted today (28 November 2023) that while strengthening flood defences can be effective in reducing climate-related losses, investment was only cost-effective to a certain level.

In turn, the two firms said that such funding should be combined with property-level flood resilience measures and strategies to address the management of surface water.

“Whilst the UK needs to continue to invest in its flood defences, this alone is not sufficient to build its resilience to flood in the wake of climate change,” said Flood Re chief executive Andy Bord.

“It is also necessary to fully embrace property-level flood resistance measures and water management strategies.”

Flood scenario study

The two firms made the claim in a study that considered severe flood scenarios for residential properties in York and Pontypridd.

This took into account the cost of property damage for the present day, with existing defences being used as a baseline.

The impact of a high and low emissions climate pathway on the baseline in 2040 was also taken into consideration as well as the impact of increasing flood defence standards.

The findings revealed that climate change would erode existing defence standards of protection (SoP) over the study period, resulting in increases in loss equating to millions of pounds for York and Pontypridd.

For example, York, which is densely populated but has high standards of flood protection, would see a £11m to £20m increase in additional losses under a one in 50-year flood scenario by 2040.

And Pontypridd, which is less populated and less protected, would see additional losses of between £8m and £17m.

“The UK is one of the best defended countries in the world for flood risk, however, climate change presents an enormous challenge to defence infrastructure,” said Moody’s RMS senior product manager Daniel Bernet.

Improving resiliency

The Representative Concentration Pathway (RCP) scenarios considered were RCP2.6 and RCP8.5

UKCP18 Guidance: Representative Concentration Pathways, published by the Meteorological Office on 26 February 2019, states that RCP2.6 and RCP8.5 represent a global mean temperature increase of 1.6 and 4.3 by 2081 to 2100.

After conducting the experiment, the study warned that while strengthening both areas’ flood defences would offset the additional losses, investment would suffer from a “diminishing return”.

For example, if a 50% increase in SoP was applied for Pontypridd in the 2040 RCP2.6 scenario compared to existing defences, it would yield a reduction of £14m in losses.

A 100% increase in SoP, furthermore, would only yield a further £5.5m in loss reduction.

Bord said that Flood Re will “continue its work with the insurance market and government to ensure by the time we exit in 2039, UK housing is more resilient to flooding and householders are still able to obtain affordable insurance.”