Association of British Insurers warns of 40cm rise in sea levels by 2040, putting a total of 400,000 properties at risk of flooding

The government needs to spend £9bn bolstering flood defences in anticipation of a 40cm rise in sea levels caused by global warming, according to a report by insurers.

Without carrying out substantial work, the Association of British Insurers warned that damage from a single major flood could hit London and the east cost of England causing £16bn of damage.

The report, Coastal flood risk-Thinking for tomorrow, acting today, said a 40cm rise in sea levels could happen by 2040 and would put an extra 130,000 properties at risk of flooding. The total number of properties at risk would be 400,000, an increase of 50% on the current figures.

The ABI report said improvements to flood management could cut the cost of a major flood to £6.8bn.

It said up to £4bn was needed to improve the Thames Barrier and central London's flood defences, with an extra £2bn on a tidal flood plain beside of the barrier.

Along the east coast, which was hit in 1953 by a storm surge that killed more than 300 people, £2.6bn needed to be spent.

Stephen Haddrill, director general of the ABI, said: "Climate change is happening now and we need to act now to manage it. Flooding is expensive, disruptive and distressing.

"This report shows that Britain needs a sustained and prolonged investment in coastal flood defences. This investment needs to start now."