Climate Change: Sea Rise 'To Have Impact'

Rising sea levels over the next century could have an impact on coasts and cities such as London, new research suggests.

The study, based on new modelling of how climate change will affect the loss of ice in Greenland and Antarctica, cites various factors as adding to the sea-level rise, which could be more significant than previously predicted.

A global review of climate science published in 2007 by the Intergovernmental Panel on Climate Change (IPCC) estimated sea levels could rise by between 18cm to 59cm (7-23in) by 2100.

The new research suggests warmer climate would lead to higher sea level rises and bigger storm surges.

Ice loss will contribute 3.5cm to 36.8cm (1.4-14in) to average global sea-level rise, according to the new study.

Once other factors are taken into account, such as the increase in volume of the oceans as they warm, the "best guess" for overall rise in sea levels globally could be from 6cm (2.4in) up to 69cm (27in), the researchers said.

Extreme storm-surge events expected to occur just once every 50 years are predicted to be almost a metre higher when they hit European coasts.

Professor David Vaughan, of the British Antarctic Survey who is coordinating the programme, said: "Today as the glaciers and ice sheets lose their ice, the water that they once held has melted and flowed in to rivers and seas, increasing their volume and raising global sea levels.

"Current rates of sea-level rise are already having impacts on the most vulnerable communities and ecosystems."

Sea-level rise will vary from region to region, with the Pacific where there are many low-lying islands expected to experience the greatest increases and European coastlines likely to see a sea level rise of less than the global average.

But this will still have an impact on coastal areas such as the Thames Estuary, where the Thames Barrier provides protection to London from storm surges so high they would only be expected once in a 1,000 years.

If the sea level in the estuary was to rise by 50cm (20in), without action being taken to provide further flood protection, the barrier could be expected to be overtopped by a storm once every 150 years.

If sea levels rose by a metre (40in) the barrier could be breached every 12 years, said a report by the Ice2sea programme, made up of experts from 24 leading institutions in Europe and beyond.

The Environment Agency has developed a plan to adapt flood defences to maintain protection to London.

Sensitive natural environments such as the machair meadows on Scotland and Ireland's low-lying Atlantic coasts could also be damaged by an increase in flooding, with a sea level rise of 50cm leading to one-in-1,000-year storms occurring every decade.

Professor Vaughan said: "It is likely some future ice loss and sea level rise is now unavoidable.

"But nevertheless, understanding why changes are occurring today and how they could increase in the future is the first step in maintaining the security of our coastal regions for future generations."