Anthropogenic Carbon Concentrations in the North Pacific Ocean: Implications for Ocean Acidification Changes Since the Pre-industrial Era
Abstract
Anthropogenic carbon (Canth) distributions in the Pacific Ocean have been determined from repeat hydrographic cruises which have been occupied between 1991 and 2017 as part of the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). The basin-wide rate of change of Canth is estimated using a new approach that combines the extended multiple linear regression method with improvements to address difficulties associated with analyzing multiple occupations of sections spaced irregularly in time. The Canth buildup over the top 1500m of the Pacific increased from 8.8 (±1.1, 1σ) Pg of carbon per decade between 1995 and 2005 to 11.7 (±1.1) PgC per decade between 2005 and 2015. The corresponding impacts of surface Canth on pH are greatest in the colder waters, with 0.04 larger surface pH decreases at high latitudes. Along the west coast of North America Canth uptake increases at the rate of 0.8-1.2 µmol kg-1 yr- 1, with the rate decreasing from south to north to in surface waters. The rates gradually decrease with depth to values of ~0.3 μmol kg-1 yr-1 at depths near 400 m. Corresponding rates of pH decrease on average about 0.002 yr-1 in surface waters. In future years, the rates will be driven by CO2 emissions and the changes in carbon chemistry that reduce the buffer capacity of subsurface waters (i.e., increasing Revelle Factor) with increasing remineralized CO2, with the largest impacts on pH and CO2 partial pressure (pCO2) occurring in the colder waters at higher northern latitudes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMOS43C1730F
- Keywords:
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- 4299 General or miscellaneous;
- OCEANOGRAPHY: GENERAL;
- 6620 Science policy;
- POLICY SCIENCES & PUBLIC ISSUES