Tuvalu’s islands rising says new report

FUNAFUTI – Despite ongoing sea level rise, the main atoll in the south Pacifi c nation of Tuvalu has grown in size over the past 100 years – according to fi ve scientists whose four-page paper was published earlier this month by the Geological Society of America.

“The geological stability and existence of low-lying atoll nations is threatened by sea-level rise and climate change,” the scientists, who are based in New Zealand and Australia, wrote in their paper. “Funafuti has experienced some of the highest rates of sealevel rise, totaling about 30 centimetres over the past 60 years.” They analysed time slices of shoreline position over the past 118 years at 29 islands in Funafuti Atoll to evaluate their response to recent sea-level rise. “Despite the magnitude of this rise, no islands have been lost, the majority have enlarged, and there has been a 7.3 per cent increase in net island area over the past century from 1897 to 2013,” the article said. “There is no evidence of heightened erosion over the past half-century as sea-level rise accelerated.”

The scientists said the study at Funafuti showed that reef islands “adjust their size, shape, and position in response to variations in boundary conditions, including storms, sediment supply, as well as sea level.” The scientists said these results suggest “a more optimistic prognosis for the habitability of atoll nations and demonstrate the importance of resolving recent rates and styles of island change to inform adaptation strategies.”

They noted that some islands in Funafuti had decreased in size. But the overall land area of the atoll has increased by over seven percent. “Our data show that reef islands are both robust and dynamic landforms that continually alter their size, shape, and orientation” in response to numerous impacts, including climate change, the scientists said. They said the Tuvalu data showed that islands can persist on reefs with sea level rise of five millimeters a year. They noted, however, that in the future sea level is projected to rise at double this rate.

“It is unclear whether islands will continue to maintain their dynamic adjustment at these higher rates of change,” they said.

“The challenge for low-lying atoll nations is to develop flexible adaptation strategies that recognize the likely persistence of islands over the next century, recognize the different modes of island change, and accommodate the ongoing dynamism of island margins.”