How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

The Response of Reef Islands to Warming-Induced Sea-Level Rise
Webb, A.P. and Kench, P.S. 2010. The dynamic response of reef islands to sea-level rise: Evidence from multi-decadal analysis of island change in the Central Pacific. Global and Planetary Change 72: 234-246.

"Under current scenarios of global climate-induced sea-level rise," in the words of the authors, "it is widely anticipated that low-lying reef islands will become physically unstable and be unable to support human populations over the coming century." What is more, they say "it is also widely perceived that island erosion will become so widespread that entire atoll nations will disappear, rendering their inhabitants among the first environmental refugees of climate change." In fact, members of the Maldives' Cabinet donned scuba gear last year (17 October 2009) and used hand signals to conduct business at an underwater meeting, which was staged to highlight the purported threat of global warming to the very existence of their country's nearly 1200 coral islands, where they signed a document calling on all nations of the earth to reduce their carbon emissions, based on climate-alarmist claims that the greenhouse effect they say these emissions produce is raising temperatures, melting glacial and polar ice, and causing seawater to expand and inundate low-lying islands.

What was done
In a study designed to explore the seriousness of this situation, Webb and Kench examined the morphological changes of 27 atoll islands located in the central Pacific in four atolls that span 15 degrees of latitude from Mokil atoll in the north (641.01'N) to Funafuti in the South (830.59'S). This they did using historical aerial photography and satellite images over periods ranging from 19 to 61 years, during which time interval they say that instrumental records indicated a rate of sea-level rise of 2.0 mm per year in the central Pacific.

What was learned
The two researchers -- one from Fiji and one from New Zealand -- say "there is no evidence of large-scale reduction in island area despite the upward trend in sea level," and that the islands "have predominantly been persistent or expanded in area on atoll rims for the past 20 to 60 years." More specifically, they say that 43% of the islands "increased in area by more than 3% with the largest increases of 30% on Betio (Tarawa atoll) and 28.3% on Funamanu (Funafuti atoll)."

What it means
In the words of the scientists who conducted the analysis, the results of this study "contradict widespread perceptions that all reef islands are eroding in response to recent sea level rise." Quite to the contrary, they note that "reef islands are geomorphically resilient landforms that thus far have predominantly remained stable or grown in area over the last 20-60 years," and they say that "given this positive trend, reef islands may not disappear from atoll rims and other coral reefs in the near-future as speculated."

Reviewed 18 August 2010