Projected mangroves on Pohnpei, 2060, under 117 cm of sea-level rise

Projected mangrove distribution on the island of Pohnpei, 2037, under a 117 cm of sea-level rise scenario.

Model projections for Pohnpei indicate that the mangroves are likely to be resilient to low and moderate rates of sea-level rise over the coming decades if they remain intact and healthy. Under 37 cm or 67 cm of sea level rise, predictions showed limited changes in species composition over the next 30 years, with some expansion of low elevation species and possible losses of high elevation species by 2100 in some parts of the island.

However, under the most extreme sea-level rise scenario, 117 cm of sea-level rise, mangrove elevation decreased substantially relative to mean sea level, with more drastic changes in the tree species composition starting in 2060 and loss of mangroves by 2100. Vulnerability to sea-level rise varied across the island, with mangroves on the leeward side of the island generally the most at-risk to high rates of sea-level rise.

The model’s predictions are limited to the effects on elevation and tree species composition. The potential effects of sea-level rise on other parts of the mangrove ecosystem, such as bird and fish communities, are currently unknown.