David Evans emailed to point out wikipedia Thames Barrier entry quotes EA saying Environment Agency responded that it does not plan to replace the Thames Barrier before 2070, as the barrier was designed with an allowance for sea level rise of 8 mm per year until 2030, which has not been realised in the intervening years.
The Thames Barrier was opened in 1982, 48 years before 2030. Which suggests the barrier was built to cope with a rise in sea level from 1982 of 48 × 8 = 484 mm.
There are 88 years between 1982 and 2070 which suggests EA now expects an average rise of no more than 5.5 mm/year.
This is curious as rate of sea level rise as measured by tide gauges at nearby location are
|Southend||1.2 ± 0.2 mm/year|
|Sheerness||1.67 ± 0.04 mm/year|
|Tilbury||1.7 ± 0.6 mm/year|
An article in Telegraph on 18 Feb 2014 quotes Dick Tappin, an engineer who helped design in the barrier in 1970s and who has worked on it ever since, the barrier will work into 22th century.
If the barrier lasted until 2200, 218 years from when it opened, this would suggest an average rate of sea level rise of 2.2 mm/year, still more than what is measured by tide gauges.