Sea levels could rise by a "catastrophic" 10 feet by the end of the century â€“ putting millions of people at risk of flooding with coastal cities such as London, New York, Tokyo and Calcutta submerged, according to a new study.
The melting of the vast ice sheets in Antarctica and Greenland caused water to pour into the world's oceans at an alarming rate at the end of the last period of global warming, the study shows.
Analysis of fossilised coral reefs off the Gulf of Mexico found many died during this time â€“ known to climatologists as an "interglacial" â€“ and were replaced by new reefs on higher ground.
This happened over a long-term ecological timescale and was caused by a rapid jump in sea level of between 6.5ft and 9.8ft (two to three metres) that occurred around 121,000 years ago, say the researchers.
The findings published in Nature raise concerns that current climate change could yield similar quick ice loss and disastrous sea-level rise in the near future.