Study: Global warming case study Tuvalu land area increasing

by Michael Hansen, Hawaii Shippers Council, February 12, 2018

The New Zealand online news site Scoops published a press release, “Land area of low-lying Tuvalu has increased,” issued by the University of Auckland on February 10, 2018.

It announced the result of a study, “Patterns of island change and persistence offer alternate adaptation pathways for atoll nations pathways for atoll nations,“ published online by the journal Nature Communications on February 9, 2018.

Tuvalu is an independent Pacific Island nation made up of nine coral atolls with a Polynesian population of approximately 11,000 inhabitants, and located north of Fiji and Northwest of Samoa. Tuvalu has been inhabited by Polynesians for more than 2,000 years.

Previously Tuvalu was known the Ellice Islands and were part of the British Colony of the Gilbert and Ellice Islands. Tuvalu became independent in 1978.

Tuvalu has been held-up globally as case study of a place where sea level rise due to man-made global warming will destroy the ability of people to inhabit it.

The study conducted by a group of scientists from the University of Auckland has been objected to by the Prime Minister of Tuvalu, Enele Sopoaga, who said in Suva, Fiji, that “the recently-released University of Auckland research pointing to an increase in his country’s land mass is flawed” as reported by The Fiji Times on February 12, 2018.

Key excerpts from Scoop

The tiny Pacific island nation of Tuvalu, thought to be under threat from sea level rise, has actually expanded in land area over the past 40 years and is likely to continue to be habitable a century from now, scientists say.

New research from the University of Auckland published today in Nature Communications mapped shoreline change of each of Tuvalu’s 101 islands across its nine atolls over a 40-year period.

Eleven of the remote and sparsely populated country’s islands have a permanent human population, two have a population of more than 600.

The research team, including Professor Paul Kench, Dr Murray Ford and Dr Susan Owen from the School of Environment, used aerial photos going as far back as 1943, and photo collections from 1971 and 1984 with updated satellite imagery from 2004-2014, to compare how the shoreline of each atoll changed between 1971 and 2014.

Mapping of island size and position shows that Tuvalu has experienced a net increase in land area of 2.9 percent or 73.5ha. Overall 74 percent of islands in the group – a total of 73 – are larger now than forty years ago.

Yet sea level rise in the region has been happening at twice the global average over the past 40 years.

“We tend to think of Pacific atolls as static landforms that will simply be inundated as sea levels rise but there is growing evidence these islands are geologically dynamic and are constantly changing,” says Professor Kench.

Tuvalu has long been considered one of the low-lying Pacific nations at threat from sea level rise caused by climate change and over the 40-year period of the study, local sea levels rose at twice the global average.

“The study findings may seem counterintuitive given that sea level has been rising in the region over the past half century, but the dominant mode of change over that time on Tuvalu has been expansion, not erosion.”

Professor Kench says sea level is just one factor that can influence island change. A range of environmental processes have contributed to that pattern including sediment supply and wave patterns.

Those processes, particularly during extreme events such as Cyclone Bebe in 1972, could account for the expansion of larger mixed sand-gravel islands and gravel islands, while smaller islands which are predominantly sand are more likely to have been destabilised, he said.

“On the basis of this research we project a markedly different trajectory for Tuvalu’s islands over the next century and while we recognise that habitability rests on a number of factors, loss of land is unlikely to be a factor in forcing depopulation of Tuvalu.”