'More defences needed' against Thames flooding
The Thames Barrier will protect London from flooding throughout the 21st century under the Government's climate change predictions - but will not be enough to withstand severe weather under more negative climate scenarios.
Speaking at a two-day conference organised by the Tyndall Centre for Climate Change Research, Mr Reeder said other climate change scenarios suggested more defences will be needed to maintain the current level of protection.
Using a climate change scenario from the UK Climate Impacts Programme where storm surge magnitude is predicted to increase by 0.4m, Mr Reeder said the Thames Barrier would be overtopped if sea levels rose by 1.75m.
An outer estuary barrier near Southend-on-Sea would be topped if sea levels rise by 4m, but the building of a barrage at Southend would protect London until sea levels rise by 5.75m.
Mr Reeder said: "A new barrage is the option that would have the most defence against high sea level rises."
He added that adaptation to flood risks needs to become more proactive, noting that it took 30 years after the 1953 floods to implement the current flood risk management system, including the barrier, which recently turned 25.
Suraje Dessai, a senior research fellow at the Tyndall Centre, argued that climate change prediction was not the most appropriate method of assessing adaptation needs because of the uncertainty of the science and the need to take into account factors other than climate.
Mr Dessai recommended that decision makers should assess the impact of their adaptation strategies over a range of scenarios and find one that could sufficiently meet all outcomes.
He said: "There are a number of tools and methods out there that allow the planning of adaptation to climate change despite the uncertainties."