Global declines in coral reef calcium carbonate production under ocean acidification and warming

• Main Authors: Cornwall, Christopher, Comeau, Steeve, Kornder, Niklas, Perry, Chris, van Hooidonk, Ruben, DeCarlo, Thomas, Pratchett, Morgan, Anderson, Kristen, Browne, Nicola, Carpenter, Robert, Diaz-Pulido, Guillermo, D'Olivo, Juan, Doo, Steve, Figueiredo, Joana, Fortunato, Sofia, Kennedy, Emma, Lantz, Coulson, McCulloch, Malcolm, González-Rivero, Manuel, Schoepf, Verena, Smithers, Scott, Lowe, Ryan
• Other Authors: Victoria University of Wellington, The University of Western Australia (UWA), The ARC Centre of Excellence for Coral Reefs Studies Townsville, Australie (ARC), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Amsterdam Amsterdam (UvA), Nova Southeastern University (NSU), University of Exeter, NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML), National Oceanic and Atmospheric Administration (NOAA), Hawaii Pacific University, ARC Centre of Excellence for Coral Reef Studies (CoralCoE), James Cook University (JCU), Australian Institute of Marine Science (AIMS), Curtin University Perth, Planning and Transport Research Centre (PATREC), California State University Northridge (CSUN), Griffith University Brisbane, Leibniz Centre for Tropical Marine Research (ZMT), University of Queensland Brisbane, Southern Cross University (SCU), University of New South Wales Sydney (UNSW)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: calcification; carbonate production; climate change; corals; [SDV]Life Sciences [q-bio]; Ocean acidification
• Online Access: https://hal.sorbonne-universite.fr/hal-03266793; https://hal.sorbonne-universite.fr/hal-03266793/document; https://hal.sorbonne-universite.fr/hal-03266793/file/e2015265118.full.pdf; https://doi.org/10.1073/pnas.2015265118/-/DCSupplemental

International audience Ocean warming and acidification threaten the future growth of coral reefs. This is because the calcifying coral reef taxa that construct the calcium carbonate frameworks and cement the reef together are highly sensitive to ocean warming and acidification. However, the global-scale effects of ocean warming and acidification on rates of coral reef net carbonate production remain poorly constrained despite a wealth of studies assessing their effects on the calcification of individual organisms. Here, we present global estimates of projected future changes in coral reef net carbonate production under ocean warming and acidification. We apply a meta-analysis of responses of coral reef taxa calcification and bioerosion rates to predicted changes in coral cover driven by climate change to estimate the net carbonate production rates of 183 reefs worldwide by 2050 and 2100. We forecast mean global reef net carbonate production under representative concentration pathways (RCP) 2.6, 4.5, and 8.5 will decline by 76, 149, and 156%, respectively, by 2100. While 63% of reefs are projected to continue to accrete by 2100 under RCP2.6, 94% will be eroding by 2050 under RCP8.5, and no reefs will continue to accrete at rates matching projected sea level rise under RCP4.5 or 8.5 by 2100. Projected reduced coral cover due to bleaching events predominately drives these declines rather than the direct physiological impacts of ocean warming and acidification on calcification or bioerosion. Presently degraded reefs were also more sensitive in our analysis. These findings highlight the low likelihood that the world's coral reefs will maintain their functional roles without near-term stabilization of atmospheric CO2 emissions.