Millions of pounds may have to be spent improving flood defence systems to protect coastal towns such as Pevensey and Shoreham & Lancing from storm surges flooding. The report, produced as part of the UK Climate Impacts Programme, says such surges are expected to become more common with global warming.

The report details the effects a rise in temperature will have on the environment as well as on agriculture, industry, tourism, business and commerce. Higher demand for water would cause wetland habitats to dry out and lead to increased pollution due to low flows failing to dilute sewage discharges and other waste, the report says. Experts say these effects would be made worse if there is further development in coastal or flood-risk areas.

The report estimates sea levels could rise as much as 50cm by 2050 in some areas such as the Solent. The rise could be so great that well-known natural features, including Hurst Spit, East Head and the Denge Peninsula could change beyond all recognition.

The report warns that coastal defences will be regularly breached, droughts could reduce wildlife-rich rivers to shallow streams and an increase in the incidence of pests and disease in livestock may hit already hard-pressed farmers.

Experts also fear an increase in average temperatures will lower the quality of drinking water, increase serious coastal erosion, the incidence of severe storms and damage rare wildlife habitats.

The report, produced by consultants WS Atkins, the Met Office, forms part of a nation-wide programme of studies which examine the impacts of climate change and the measures needed to minimise the worst effects.

National Trust environmental practises adviser Rob Jarman, said: “This report shows that one of the biggest issues is coastal change. Accelerated sea level rise will affect this process, create new risks to life, livelihoods and property and lead to demands for tougher sea defences. The Trust wants to manage its land to enable the coastline to migrate, conserve wildlife and natural beauty without risk to human life.”

Environment Agency regional surveillance manager Tim Reeder, said “Global warming would put pressure on already limited water supplies, increase river and coastal flooding and put pressure on drainage systems.”

Dr Merylyn Mckenzie-Hedger, UKCIP programme co-ordinator, said it was vital to recognise the need for action and plan for the future. She believes lives and property will be at risk unless there is a “strong presumption” against development in flood risk areas.

Dr McKenzie-Hedger said: “The South East is currently under pressure from many quarters and climate change is going to makes things worse. A new planning agenda is urgently required to prepare the region for the challenges faced from a changing climate. Doing nothing is not an option.”

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