World War II aerial photos and modern satellite imagery have uncovered the shocking stability of Andros Island’s shorelines despite rising sea levels.
Geologists have revealed how escalating sea levels over the past 80 years have affected the geography of Andros Island. Although the island’s shorelines are stable, researchers have observed significant alterations in inland marshes and mudflats.
In 2017, when the University of Miami Geologist, Robert Ginsberg passed away, his collegues have found aerial photos of the Bahamas island that Professor Robert clicked during the World War II. They compared these images with recent satellite images and revealed critical facts about the areas around Andros Island, the largest island of the Bahamas, have transformed.
Guage data shows that sea levels around this island have increased by approximately 4 inches since 1980, following global trends. “Given the rapid rate of change, we expected to see recession of the coastlines,” said University of Miami geologist Sam Purkis, coauthor of a study in Sedimentary Geology that detailed changes on Andros Island. “But the shoreline was actually quite stable.” According to the researchers, shoreline stability is due to sediment replenishment along shorelines, which has prevented erosion caused by rising sea levels.
Purkis and colleagues also unleashed drastic changes in the inland marshes and mudflats in their study. They observed extensive growth of Scytonema, that is a photsynthetic aquatic or free-floating genus of cyanobacteria, along with carbonate sediment in the sheltered areas of inland marshes. The tide channels showed a significant increase in length, width, and proliferation as a result of escalated sea levels.
Landsat data uncovered that despite being struck by multiple Category 5 and 6 storms, they caused minimal impacts on the island’s mudflats, marshes, or channels.
Purkis said, “One of the lessons from what’s happened on Andros is that the effects of sea level rise are not uniform or intuitive. As sea level continues to rise, people should understand that shorelines might stay in place in some areas, while inland marshes might expand and hollow out islands from the inside.”
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