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Though the sea level is rising, in the South Pacific, many low-lying islands are actually growing. Two studies published this year by the same team of researchers show that islands in the Federated States of Micronesia and the Gilbert Islands in the Republic of Kiribati have expanded their areas since the 1940s. The research is the latest in a line of studies demonstrating that not all low-lying islands are doomed to drown.
In both studies, geomorphologists compared aerial reconnaissance photos captured during the Second World War with current satellite imagery. They ruled out landforms obscured by clouds or captured in low-resolution, as well as modified urban atolls like Tarawa, where half the population of Kiribati resides. In total, the scientists mapped 175 sparsely populated or entirely uninhabited islands, and compared how each had shifted, stretched, rotated, and sometimes shrunk over the past several decades.
The team found that while some islands shrank, plenty more expanded. Overall, Micronesia increased its land area by roughly three percent since the 1940s, while the Gilberts collectively expanded by 2.45 percent. While that’s an area the size of New York City’s Central Park sprinkled among 175 islands, it’s noteworthy considering that the rate of sea level rise in the region exceeds the global mean.
“There’s a lot of variability, and every island is very unique in their responses,” says Meghna Sengupta, a doctoral candidate at the University of Auckland in New Zealand and coauthor of the studies. Some islands had shifting spits, some neighbors merged together, and three islands in western Micronesia disappeared while three more formed nearby. “Islands are not static, inert landforms just sitting in a bucket,” Sengupta says.
Paul Kench, a coastal geoscientist at Simon Fraser University in British Columbia and coauthor on the papers, has completed similar studies of other island nations. No matter the location, storminess, or sea level, he’s found that—when taken as a unit—low-lying islands collectively demonstrate gradual growth. That counters the popular narrative that islands in the South Pacific are drowning, and Kench has seen his research politicized in the past.
In 2018, for instance, Australian member of Parliament and climate skeptic Craig Kelly used Kench’s survey of Tuvalu, which found the country’s 101 islands collectively grew 2.9 percent in the past 40 years, to argue against taking action to prevent climate change. Tuvalu’s then–prime minister, Enele Sopoaga, dubbed the research “irresponsible.”
But Kench sees value in the work, especially in light of the dominant doom-and-gloom narrative. “If a country is simply disappearing, there’s not a hell of a lot you can do,” he says. By demonstrating that islands are persistent, there’s a chance to adapt. “I think that’s a more powerful narrative.”
While the trend toward island growth is evident, there are important caveats, says Gerd Masselink, a geomorphologist at the University of Plymouth in England who was not involved in the studies. For one, the aerial surveys disregard island height, which is clearly important in the fight against sea level rise. Also, Masselink notes, sea level rise has only shifted by centimeters in the past few decades. The ocean’s regular processes may play a larger role in planform area, which is the shape of the island when viewed from above. “Any planform changes on the islands could just be a product of waves, tides, and surges,” he says.
Still, no one involved doubts the threat of sea level rise. “Persistence doesn’t mean the island isn’t vulnerable,” notes Sengupta.
While the inhabitants of island countries are often left with two options for dealing with sea level rise—the trauma of leaving their homeland, or the expense of defensive infrastructure—the aerial studies present a third option: adapting along with the islands’ changes. Infrastructure that blocks waves will block the sediment these islands need to grow. Designs that help communities adapt to periodic flooding will allow residents to remain in place. What those designs look like—for example, elevated pipes or protected gardens—remains to be determined.
Kench says that by looking at where islands are shrinking and growing, countries can adopt new strategies for land planning and development. “There are possibilities to stay in-country, but you’re going to need help from the outside world,” he says. “Our work is really laying the information foundation to make some of those decisions.”