A British plan to drill into a sunless lake deep under Antarctica’s ice in December could show the risks of quicker sea level rise caused by climate change, scientists said yesterday.

Sediments on the bed of Lake Ellsworth, which is several hundred metres below sea level and buried under three kilometres of ice, may include bits of ancient seashells that could be dated to reveal when the ice sheet last broke up.

Experts say the West Antarctic ice sheet over the lake contains enough ice to raise world sea levels by three to five metres if it ever broke up – a threat to low-lying areas from Bangladesh to Florida, from Buenos Aires to Shanghai.

“Society needs to know the risk of a collapse,” of the ice sheet, said Martin Siegert, of the University of Bristol and principal investigator for the mission that will also look for unknown life forms in a rivalry with Russian and US scientists.

There are 360 known sub-glacial lakes in Antarctica – formed by heat from the Earth melting the bottom of the ice.

“One way to find out (the risks of collapse) is to know when it last happened,” he said of the mission that has been in the planning stages for 16 years. “We are finally ready to hit the ‘go’ button,” he said.

“We set foot on the ice again in October and hope to bring samples to the surface in December 2012,” Chris Hill, programme manager at the British Antarctic Survey, said in a statement.