A University of Auckland study examined changes in the geography of Tuvalu's nine atolls and 101 reef islands between 1971 and 2014, using aerial photographs and satellite imagery.

It found eight of the atolls and almost three-quarters of the islands grew during the study period, lifting Tuvalu's total land area by 2.9 percent, even though sea levels in the country rose at twice the global average.

Co-author Paul Kench said the research, published Friday in the journal Nature Communications, challenged the assumption that low-lying island nations would be swamped as the sea rose.

"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," he said.