Sea-level rise is bad news for many island nations, but it may not be severe enough to prevent Chagos islanders from returning home four decades after they were expelled by UK authorities.

In the late 1960s, the 1000 or so inhabitants of the Chagos islands – a British overseas territory – were forced out to make way for American military. The UK has resisted all demands made in its courts by the Chagossians to be allowed to return to the outer islands of the archipelago.

Central to the British refusal has been the claim that the coral islands would be uninhabitable within decades because of rising sea levels due to climate change.

A management plan for the islands, written in 2003 by biologist Charles Sheppard at the University of Warwick, UK, said annual sea-level rise since a tide gauge was installed in 1988 had averaged 5.4 millimetres a year – twice the global average.


He added that the figure was accelerating, and earlier this year at an event at the Royal Geographical Society in London, he revised the annual figure to 12.0 millimetres.

Definitely wrong

Philip Woodworth, a researcher at the UK’s National Oceanography Centre in Liverpool, says these figures are “definitely wrong”. He agrees that high year-on-year variability, created by ocean-current fluctuations, means there are legitimate arguments about the precise underlying rise. But his best estimate, based on an analysis of the same data and to be published in Global and Planetary Change, is that sea level has been rising by just 2.2 millimetres a year since 1988.

Sheppard dismisses the new findings, but the issue will no doubt come up again when the two researchers attend future meetings to discuss the islands. Whatever the true measure, it should “certainly not be used for extrapolation” of future sea levels, says Woodworth.

This is what the British government has been doing, though. Since publishing a study in 2002 on the feasibility of repatriating the Chagossians – who currently live in Mauritius, the Seychelles and the UK – ministers have repeatedly cited such extrapolations as a “clear and compelling” reason why resettlement is “unfeasible”.