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

Abstract

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.

Rapid Shifts in Bacterial Communities and Homogeneity of Symbiodiniaceae in Colonies of Pocillopora acuta Transplanted Between Reef and Mangrove Environments

“…Coral reefs worldwide are rapidly deteriorating as a consequence of increasingly frequent and severe marine heatwaves (e.g., Hughes et al, 2018 ), chronic ocean warming, acidification and deoxygenation ( Altieri et al, 2017 ; Cornwall et al, 2021 ). Climate change projections indicate that by 2030, most coral reef environments will exceed the current temperature, pH and/or O 2 thresholds that govern optimal coral reef functioning ( Hoegh-Guldberg et al, 2017 ; Hughes et al, 2018 , 2020 ), threatening reef survival.…”

A National Status Report on United States Coral Reefs Based on 2012–2018 Data From National Oceanic and Atmospheric Administration’s National Coral Reef Monitoring Program

“…One jurisdiction already received an Impaired score (Florida). Climate change currently poses the greatest threat to coral reefs worldwide as a result of warming ocean temperatures and ocean acidification (Cornwall et al, 2021). Global climate change models (IPCC, 2014;Zhou et al, 2021) predict 1-3 • C of sea surface temperature warming which will continue to lead to mass bleaching events and associated coral mortality.…”

Community assessment of crustose calcifying red algae as coral recruitment substrates

“…The coral reefs of Micronesia are known for their high diversity of acroporid corals in the shallow forereef zones [17]. Acroporids are major reef builders due to their high benthic cover and fast growth rates [17, 18], thus creating habitat diversity for other reef organisms [19].…”

“…The coral reefs of Micronesia are known for their high diversity of acroporid corals in the shallow forereef zones [17]. Acroporids are major reef builders due to their high benthic cover and fast growth rates [17,18], thus creating habitat diversity for other reef organisms [19]. Guam's acroporid corals have undergone extensive mortality in recent years, particularly in the forereef zone, due to bleaching events caused by episodes of elevated seawater temperatures in 2013, 2014, 2016, extreme low tides in 2015, and high predation from Acanthaster planci [1][2][3][4][5][6].…”