The exposure of the Great Barrier Reef to ocean acidification

• Published in: Nature Communications
• Main Authors: Mongin, M, Baird, ME, Tilbrook, B, Matear, RJ, Lenton, A, Herzfeld, M, Wild-Allen, K, Skerratt, J, Margvelashvili, N, Robson, BJ, Duarte, CM, Gustafsson, MSM, Ralph, PJ, Steven, ADL
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2016
• Subjects: Earth Sciences; Oceanography; Chemical Oceanography; Ocean acidification
• Online Access: https://doi.org/10.1038/ncomms10732; http://www.ncbi.nlm.nih.gov/pubmed/26907171; http://ecite.utas.edu.au/117245

The Great Barrier Reef (GBR) is founded on reef-building corals. Corals build their exoskeleton with aragonite, but ocean acidification is lowering the aragonite saturation state of seawater (Ω a ). The downscaling of ocean acidification projections from global to GBR scales requires the set of regional drivers controlling Ω a to be resolved. Here we use a regional coupled circulationbiogeochemical model and observations to estimate the Ω a experienced by the 3,581 reefs of the GBR, and to apportion the contributions of the hydrological cycle, regional hydrodynamics and metabolism on Ω a variability. We find more detail, and a greater range (1.43), than previously compiled coarse maps of Ω a of the region (0.4), or in observations (1.0). Most of the variability in Ω a is due to processes upstream of the reef in question. As a result, future decline in Ω a is likely to be steeper on the GBR than currently projected by the IPCC assessment report.