Anthropogenic Carbon Increase has Caused Critical Shifts in Aragonite Saturation Across a Sensitive Coastal System

Jarnikova, Tereza (2022) Anthropogenic Carbon Increase has Caused Critical Shifts in Aragonite Saturation Across a Sensitive Coastal System. Global Biogeochemical Cycles. ISSN 0886-6236

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Abstract

Estuarine systems host a rich diversity of marine life that is vulnerable to changes in ocean chemistry due to addition of anthropogenic carbon. However, the detection and impact of secular carbon trends in these systems is complicated by heightened natural variability as compared to open-ocean regimes. We investigate biogeochemical changes between the pre-industrial (PI) and modern periods using a high-resolution, three-dimensional, biophysical model of the Salish Sea, a representative Northeast Pacific coastal system. While the seasonal amplitude of the air-sea difference in pCO2 has increased on average since pre-industrial times, the net CO2 source has changed little. Our simulations show that inorganic carbon has increased throughout the model domain by 29–39 mmol m−3 (28–38 µmol kg−1) from the pre-industrial to present. While this increase is modest in a global context, the region's naturally high inorganic carbon content and the low buffering capacity of the local carbonate system amplify the resultant effects. Notably, this increased carbon drives the estuary toward system-wide undersaturation of aragonite, negatively impacting shell-forming organisms. Undersaturation events were rare during the pre-industrial experiment, with 10%–25% of the domain undersaturated by volume throughout the year, while under present-day conditions, the majority (55%–75%) of the system experiences corrosive, undersaturated conditions year-round. These results are extended using recent global coastal observations to show that estuaries throughout the Pacific Rim have already undergone a similar saturation state regime shift.

Item Type:	Article
Additional Information:	Data Availability Statement: Model results, Fortran code, and analysis and figures code are archived at the the Federated Research Data Repository, https://doi.org/10.20383/101.0295. Analysis code is available at the following repository: https://github.com/tjarnikova/PI_CARBON_PAPER.
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	University of East Anglia Schools > Faculty of Science > Tyndall Centre for Climate Change Research Faculty of Science > Research Centres > Tyndall Centre for Climate Change Research
Depositing User:	LivePure Connector
Date Deposited:	20 Mar 2026 12:30
Last Modified:	20 Mar 2026 12:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/102507
DOI:	10.1029/2021GB007024

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