Island flooding likely to increase dramatically as coral reefs die
FRISCO —Besides losing critical marine nurseries, the decline of coral reefs will put some island communities at direct risk of flooding and even threaten freshwater drinking supplies, according to a new study that tries to project how climate change will affect the ability of coral reefs to mitigate coastal hazards.
About 30 million people living on low-lying coral islands and atolls are dependent on ecosystem services provided by reefs. Right now, some of those islands see flooding from large waves a few times each decade, but that number is expected to increase dramatically.
Dead, smooth corals don’t have nearly the wave-breaking power of healthy reefs, said the researchers from Deltares, an independent Dutch research institute, whose findings were supported by U.S. Geological Survey data on coral reef sensitivity to climate change. The findings will be published in Geophysical Research Letters, a journal of the American Geophysical Union.
The loss of sparse drinking water resources on some islands, may eventually make them uninhabitable, the scientists said after using a computer model validated with observational data fromKwajalein Atoll in the Marshall Islands in the Pacific Ocean. Reef roughness, steepness, width and the total water level on the reef platform are all important factors for coastal managers to consider when planning mitigating measures, according to the study’s authors.
The results suggest that coasts fronted by relatively narrow reefs with steep faces and deeper, smoother reef flats are expected to experience the highest wave runup and thus the greatest potential for island flooding.
Wave runup increases for higher waves, higher water levels that are expected with sea level rise, and lower bed roughness that occurs as coral degrades and becomes smoother. These are all expected effects of climate change. Rising sea levels and climate change will have a significant negative impact on the ability of coral reefs to mitigate the effects of coastal hazards in the future, according to the new study.