Publication Date:
2022-05-25
Description:
Author Posting. © Oceanography Society, 2009. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 22 no. 4 (2009): 36-47.
Description:
The uptake of anthropogenic CO2 by the global ocean induces fundamental changes
in seawater chemistry that could have dramatic impacts on biological ecosystems in
the upper ocean. Estimates based on the Intergovernmental Panel on Climate Change
(IPCC) business-as-usual emission scenarios suggest that atmospheric CO2 levels
could approach 800 ppm near the end of the century. Corresponding biogeochemical
models for the ocean indicate that surface water pH will drop from a pre-industrial
value of about 8.2 to about 7.8 in the IPCC A2 scenario by the end of this century,
increasing the ocean’s acidity by about 150% relative to the beginning of the industrial
era. In contemporary ocean water, elevated CO2 will also cause substantial reductions
in surface water carbonate ion concentrations, in terms of either absolute changes
or fractional changes relative to pre-industrial levels. For most open-ocean surface
waters, aragonite undersaturation occurs when carbonate ion concentrations drop
below approximately 66 μmol kg-1. The model projections indicate that aragonite
undersaturation will start to occur by about 2020 in the Arctic Ocean and 2050 in
the Southern Ocean. By 2050, all of the Arctic will be undersaturated with respect to
aragonite, and by 2095, all of the Southern Ocean and parts of the North Pacific will
be undersaturated. For calcite, undersaturation occurs when carbonate ion concentration
drops below 42 μmol kg-1. By 2095, most of the Arctic and some parts of the
Bering and Chukchi seas will be undersaturated with respect to calcite. However, in
most of the other ocean basins, the surface waters will still be saturated with respect to
calcite, but at a level greatly reduced from the present.
Description:
S. Cooley and S. Doney acknowledge
support from NSF ATM-0628582.
Richard A. Feely was supported by the
NOAA Climate Program under the
Office of Climate Observations (Grant
No. GC04-314 and the Global Carbon
Cycle Program (Grant No. GC05-288).
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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