Articles | Volume 13, issue 17
Biogeosciences, 13, 5065–5083, 2016
Biogeosciences, 13, 5065–5083, 2016

Research article 13 Sep 2016

Research article | 13 Sep 2016

Using present-day observations to detect when anthropogenic change forces surface ocean carbonate chemistry outside preindustrial bounds

Adrienne J. Sutton1,2, Christopher L. Sabine2, Richard A. Feely2, Wei-Jun Cai3, Meghan F. Cronin2, Michael J. McPhaden2, Julio M. Morell4, Jan A. Newton5, Jae-Hoon Noh6, Sólveig R. Ólafsdóttir7, Joseph E. Salisbury8, Uwe Send9, Douglas C. Vandemark8, and Robert A. Weller10 Adrienne J. Sutton et al.
  • 1Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA
  • 2Pacific Marine Environmental Laboratory, NOAA, Seattle, WA 98115, USA
  • 3School of Marine Science and Policy, University of Delaware, Newark, DE 19716, USA
  • 4Department of Marine Sciences, University of Puerto Rico, Mayagüez, 00681, Puerto Rico
  • 5Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
  • 6Korea Institute of Ocean Science and Technology, Ansan Gyunggido 15627, South Korea
  • 7Marine Research Institute, Skulagata 4, 101 Reykjavik, Iceland
  • 8Ocean Processes Analysis Laboratory, University of New Hampshire, Durham, NH 03825, USA
  • 9Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
  • 10Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA

Abstract. One of the major challenges to assessing the impact of ocean acidification on marine life is detecting and interpreting long-term change in the context of natural variability. This study addresses this need through a global synthesis of monthly pH and aragonite saturation state (Ωarag) climatologies for 12 open ocean, coastal, and coral reef locations using 3-hourly moored observations of surface seawater partial pressure of CO2 and pH collected together since as early as 2010. Mooring observations suggest open ocean subtropical and subarctic sites experience present-day surface pH and Ωarag conditions outside the bounds of preindustrial variability throughout most, if not all, of the year. In general, coastal mooring sites experience more natural variability and thus, more overlap with preindustrial conditions; however, present-day Ωarag conditions surpass biologically relevant thresholds associated with ocean acidification impacts on Mytilus californianusarag < 1.8) and Crassostrea gigasarag < 2.0) larvae in the California Current Ecosystem (CCE) and Mya arenaria larvae in the Gulf of Maine (Ωarag < 1.6). At the most variable mooring locations in coastal systems of the CCE, subseasonal conditions approached Ωarag =  1. Global and regional models and data syntheses of ship-based observations tended to underestimate seasonal variability compared to mooring observations. Efforts such as this to characterize all patterns of pH and Ωarag variability and change at key locations are fundamental to assessing present-day biological impacts of ocean acidification, further improving experimental design to interrogate organism response under real-world conditions, and improving predictive models and vulnerability assessments seeking to quantify the broader impacts of ocean acidification.

Short summary
Ocean carbonate observations from surface buoys reveal that marine life is currently exposed to conditions outside preindustrial bounds at 12 study locations around the world. Seasonal conditions in the California Current Ecosystem and Gulf of Maine also exceed thresholds that may impact shellfish larvae. High-resolution observations place long-term change in the context of large natural variability: a necessary step to understand ocean acidification impacts under real-world conditions.
Final-revised paper