The Thames Barrier will need to be strengthened to protect London from flooding, the government's chief scientific adviser has warned.
Flooding on the south coast is expected to rise dramatically
Sir David King told Radio 4's Today programme it needs to be improved within the next 20 years due to changes in climate.
He said the barrier was used once every fives years in the 1980s but now it is more like five times a year.
Barrier extensions or additional structures are considered, he said.
Sir David told a commons committee on Tuesday that it would take a major disaster for the world to take climate change seriously.
On the Today programme he said: "The very severe hot summer and drought that we had in Europe last year, it is estimated (accounted for) 30,000 fatalities.
"These extreme events are already becoming more frequent. It is a very difficult message to get through."
Sir David said flooding in some areas on the south coast could increase from once every 100 years to as much as once every three years.
He also said damage to property, which currently amounts to £20bn in the UK each year, would increase.