Hundreds of Pacific Islands are getting bigger despite global warming

Healthy coral reefs key to growth

New research says hundreds of islands in the Pacific are growing in land size, even as climate change-related sea level rises threaten the region.

The scientists used satellite images of islands as well as on-the-ground analysis to track the changes.

Coastal geomorphologist Dr Paul Kench said coral reef sediment was responsible for building up the islands.

"All the islands that we're looking at, and the atoll systems, comprise predominantly of the broken up corals, shells and skeletons of organisms on the coral reef, which waves then sweep up and deposit on the island," he said.

Dr Kench said in areas where coral reefs were healthy, enough sediment was being produced to cause islands to grow.  "The majority of islands in each of those nations has either got larger or stayed very similar in size," he said.

"So, you know, one of the remarkable takeaways of the work is that these islands are actually quite dynamic in a physical sense."

Coastal erosion from rising sea level is considered a major threat to many Pacific communities, with some already watching shorelines recede.

Dr Kench said about 10 per cent of islands captured in the study had gotten smaller in size.

He said a better understanding of which islands are growing and which are eroding could help Pacific nations adapt to climate change.

"That gives the island nations some power to think about adaptation strategies, about where do you focus further development, and you would perhaps choose those islands which we can demonstrate are actually growing in size," he said.

"So we think it's affording some different sort of strategies and opportunities for islands to think about as they're contemplating an uncertain future."

Dr Kench said there was more work to be done in understanding other factors influencing the growth or reduction of Pacific islands.

"While we can look at sites that are healthy, and the sediment production that's creating the islands is still taking place, there has to be some concerns at those locations where the reefs are in poor condition," he said.

"So we're not suggesting here by any stretch of the imagination that islands have nothing to worry about.

"I guess one of the messages from the work that we're doing is that the outcome and the prognosis for islands is going to vary quite markedly from one site to the other."

https://www.abc.net.au/news/2021-01-08/why-are-hundreds-of-pacific-islands-getting-bigger/13038430