Migrating East Australian Barriers and Reefs Under Greenhouse Scenario

Hoyt, William H.; ,

Migrating East Australian Barriers and Reefs Under Greenhouse Scenario

by William H. Hoyt, Univ of Northern Colorado, Greeley, United States,

Document Type: Proceeding Paper

Part of: Coastal Sediments

Abstract:

Geological evidence which bears directly on the question of human-induced sea-level change and migrating shorelines is difficult to find. If we could find an ancient analog of the rapid sea-level changes predicted in a future greenhouse world, then we could use information from that ancient event to help understand the future. Evidence of ancient sandy barrier islands on the now-submerged shelf is sketchy and poorly preserved. However, abundant submerged fossil reefs have been found, including one found near Heron Island on the Great Barrier Reef. There, a fossil reef flat composed principally of Acropora cervicornis (Staghorn coral) was found preserved at a depth of -21m and was radiocarbon dated at 8270 yrs BP. This information coupled with that from the literature has been used to reconstruct shoreline migration rates across the east Australian shelf during the Early Holocene. The fastest barrier migration rates during rapid deglaciation averaged about 14 m/yr. If greenhouse warming produces sea level rise as predicted through the year 2100, barrier migration will be even faster: up to 20 m/yr of erosion. The implications for barrier reef migration and loss are even more dire: more than 20 m/yr of Great Barrier Reef loss is predicted

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