As CO continues
to increase in the atmosphere, it is important to continue the work begun with
the Global Survey of CO
in
the Ocean. Because CO
is
an acid gas, the uptake of anthropogenic CO
consumes
carbonate ions and lowers the pH of the ocean. The carbonate ion concentration
of surface seawater in equilibrium with the atmosphere will decrease by about
30% and the hydrogen ion concentration will increase by about 70% with a doubling
of atmospheric CO
from
pre-industrial levels (280 to 560 ppm). As the carbonate ion concentration
decreases, the buffering capacity of the ocean and its ability to absorb more
CO
from the
atmosphere is diminished. Over the long term (millennial time scales) the ocean
has the potential to absorb as much as 85% of the anthropogenic CO
that
is released into the atmosphere. Because the lifetime of fossil fuel CO
in
the atmosphere ranges from decades to centuries, mankind's reliance on fossil
fuel for heat and energy will continue to have a significant effect on the
chemistry of the earth's atmosphere and oceans and therefore on our climate
for many centuries to millennia.
Plans are being formulated in several countries, including the United States,
to establish a set of repeat sections to document the increasing anthropogenic
inventories in the oceans. Most of these sections will follow the lines occupied
during the WOCE Hydrographic Programme on which JGOFS investigators made CO survey
measurements. The current synthesis effort will provide an important baseline
for assessment of future changes in the carbon system. The spatially extensive
information from the repeat sections, together with the temporal records from
the time-series stations and the spatial and temporal records available from
automated surface pCO
measurements
on ships of opportunity, will greatly improve our understanding of the ocean
carbon system and provide better constraints on potential changes in the future.
The authors are grateful to the members of the CO Science
Team and the JGOFS and WOCE investigators for making their data available for
this work. We thank Lisa Dilling of the National Oceanic and Atmospheric Administration
(NOAA) Office of Global Programs, Don Rice of the National Science Foundation
and Mike Riches of the Department of Energy (DOE) for their efforts in coordinating
this research. This work was supported by DOE and NOAA as a contribution to
the U.S. JGOFS Synthesis and Modeling Project (Grant No. GC99-220) and by grants
to Taro Takahashi from NSF (OPP-9506684) and NOAA (NA16GP01018). This publication
was supported by the Joint Institute for the Study of the Atmosphere and Ocean
(JISAO) under NOAA Cooperative Agreement #NA67RJO155, Contribution #832, and
#2331 from the NOAA/Pacific Marine Environmental Laboratory. This is U.S. JGOFS
Contribution Number 683.
Return to previous section or go to next section