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The Coral Atoll Islands of the Chagos Archipelago
Reference
Dunne, R.P., Barbosa, S.M. and Woodworth, P.L. 2012. Contemporary sea level in the Chagos Archipelago, central Indian Ocean. Global and Planetary Change 82-83: 25-37.

Background
The authors write that "rising sea levels are of particular relevance to low lying coastal areas of the world, including the coral atolls and islands of the world's tropical oceans," and they note in this regard that the atolls and islands of the Chagos Archipelago have been deemed "vulnerable." They indicate, for example, that "Sheppard and Spalding (2003) examined the records from a tide gauge situated on Diego Garcia in the south east of the archipelago and concluded that relative sea level had risen at a rate of 5.44 mm/year over the period 1988-1999." However, they state that another analysis of the same record published three years later for the period 1988 to 2000 reported a much smaller rate-of-rise of 4.35 mm/year (Ragoonaden, 2006). And on top of this, they add that both of these earlier analyses "were based only on short tide-gauge data sets, involved inappropriate statistical methods, and as a result have given an erroneous impression of the magnitude and significance of sea-level rise in this area."

What was done
In an effort dedicated to resolving these problems, Dunne et al. examined what they describe as "the up-to-date evidence of recent sea-level change in the Chagos Archipelago from tide gauge, satellite altimeter records, and ocean models."

What was learned
In the words of the three researchers, "there is no evidence of any statistically significant sea-level rise either from the Diego Garcia tide gauge (1988-2000 and 2003-2011) or in the satellite altimetry record (1993-2011)." In addition, they say "there is no evidence of subsidence in the islands," adding that on Diego Garcia there was actually crustal uplift of 0.63 0.28 mm/year between 1996 and 2009, as recorded by GPS. And they add that "there is no evidence of changes in the wind or wave environment in the past 20 years."

What it means
"Collectively," in the words of Dunne et al., "these results suggest that this has been a relatively stable physical environment, and that these low-lying coral islands should continue to be able to support human habitation, as they have done for much of the last 200 years."

References
Ragoonaden, S. 2006. Sea level activities and changes on the islands of the western Indian Ocean. Journal of Marine Science 5: 179-194.

Sheppard, C.R.C. and Spalding, M. 2003. Chagos Conservation Management Plan. British Indian Ocean Territory Administration. Foreign & Commonwealth Office, London, United Kingdom.

Reviewed 8 August 2012