Carbon-climate feedbacks accelerate ocean acidification

• Published in: Biogeosciences
• Main Authors: Matear, RJ, Lenton, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus GmbH 2018
• Subjects: climate feedback; ocean acidification; CO2 concentrations; Ocean acidification
• Online Access: https://eprints.utas.edu.au/29965/; https://eprints.utas.edu.au/29965/1/132050%20-%20Carbon-climate%20feedbacks%20accelerate%20ocean%20acidification.pdf

We show that simulated carbon–climate feedbacks can significantly impact theonset of undersaturated aragonite conditions in the Southern and Arcticoceans, the suitable habitat for tropical coral and the deepwater saturationstates. Under the high-emissions scenarios (RCP8.5 and RCP6), thecarbon–climate feedbacks advance the onset of surface water under saturationand the decline in suitable coral reef habitat by a decade or more. Theimpacts of the carbon–climate feedbacks are most significant for the medium-(RCP4.5) and low-emissions (RCP2.6) scenarios. For the RCP4.5 scenario, by2100 the carbon–climate feedbacks nearly double the area of surface waterundersaturated with respect to aragonite and reduce by 50 % the surfacewater suitable for coral reefs. For the RCP2.6 scenario, by 2100 thecarbon–climate feedbacks reduce the area suitable for coral reefs by 40 %and increase the area of undersaturated surface water by 20 %. Thesensitivity of ocean acidification to the carbon–climate feedbacks in the lowto medium emission scenarios is important because recent CO2 emissionreduction commitments are trying to transition emissions to such a scenario.Our study highlights the need to better characterise the carbon–climatefeedbacks and ensure we do not underestimate the projected oceanacidification.