When the Thames Barrier was being designed in the 1970s, global average sea levels were rising at about 1.8 millimetres a year and global warming was not seen as a threat, but in the past 15 years the rate has nearly doubled to about 3.1mm a year and many scientists expect it to accelerate still further.…"The defences we have at the moment allow for sea level rise and the tidal levels we're expecting by 2030. That is still some time away. However, it takes time to research, design and build tidal defences, so we're already planning how we can manage increasing flood risk in the estuary," said a spokesman for the Environment Agency. Experts working on the Thames Estuary 2100 project, who are writing a report on what needs to be done to protect London in the next 100 years, believe that past assessments on the sea level rise this century are too optimistic and have devised far higher worse-case scenarios.
A report on the options open to the Government if sea levels rise faster than expected is due to be completed next year. If sea levels are forecast to rise by two metres or more, a bigger and more expensive barrage will have to be built and raised permanently. Under the Government's estimate for a rise of less than one metre, the Thames Barrier will meet its maximum preferred closure rate of 70 times a year by about 2082. Under the extreme "high plus plus" scenario of TE2100, which envisages a four-metre rise in sea level, this limit will be reached in the early 2020s.
Few experts believe that sea levels will rise this fast in the coming century, although they accept that this depends on the rate at which ice sheets in
The Thames Barrier protects about £80bn worth of buildings and capital infrastructure in