Rising sea levels threaten one in ten people by 2100

Sea levels could rise more than a metre by 2100 threatening ten percent of the world's population unless greenhouse gas emissions are curbed, scientists have warned.

Warming oceans and melting glaciers and polar ice sheets mean some 600 million people living in low lying coastal areas are in danger being flooded, according to research presented at last week’s (March 10-12) International Scientific Congress on Climate Change at the University of Copenhagen.

Eric Rignot, senior research scientist at NASA’s Jet Propulsion Laboratory, said: “As a result of the acceleration of outlet glaciers over large regions, the ice sheets in Greenland and Antarctica are already contributing more and faster to sea level rise than anticipated.

“If this trend continues, we are likely to witness sea level rise one metre or more by year 2100.”

The new estimates is much worse than predictions given in a 2007 report by the Intergovernmental Panel on Climate Change (IPCC), which said sea levels could rise by 18cm (7.1in) to 59cm (23.2in) this century.

More detailed research into Antarctic and Greenland ice sheet loss has prompted more severe predictions.

Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado and co-chairman of the congress session on sea level rise, said: “The ice loss in Greenland has accelerated over the last decade.

“The upper range of sea level rise by 2100 might be above 1m or more on a global average, with large regional differences depending where the source of ice loss occurs.”

The scientists say even in the best case scenario, the sea level rise is unlikely to be much less than 50cm leading to a major increase in coastal floods and affecting up to one in ten humans on the planet.

Sea levels have already risen almost 20cm since 1880 and are set to accelerate as the planet warms, they say.

Dr John Church, of the Centre for Australian Weather and Climate Research in Tasmania and lead speaker in the conference sea level session, said: “The most recent satellite and ground based observations show that sea-level rise is continuing to rise at 3 mm/yr or more since 1993, a rate well above the 20th century average.

“The oceans are continuing to warm and expand, the melting of mountain glacier has increased and the ice sheets of Greenland and Antarctica are also contributing to sea level rise.”

The faster humans limit carbon dioxide emissions the better the chance of avoiding the worst case scenarios.

“Unless we undertake urgent and significant mitigation actions, the climate could cross a threshold during the 21st century committing the world to a sea level rise of metres,” he said.

More than 2,000 delegates from some 80 countries attended the conference aimed at persuading politicians to take stronger action on global warming.

Among their final conclusions, they said: “Rapid, sustained, and effective mitigation based on coordinated global and regional action is required to avoid dangerous climate change.”

David Gibbs

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie