Direct Evidence for Ocean Acidification of the North Pacific Ocean
Abstract
One goal of the CLIVAR/CO2 Repeat Hydrography Program is to improve our understanding of the ocean response to rising atmospheric CO2 levels. The North Pacific Ocean plays a unique role in controlling the ocean carbon cycle because it is the final destination of circulation of the deep water that contains a high level of preformed nutrients and dissolved inorganic carbon (DIC) and shallow saturation depths for calcium carbonate. Discrete high-quality dissolved inorganic carbon, pH (P16N 1991 cruise) and total alkalinity data were acquired as part of the WOCE/JGOFS Global CO2 survey cruises in 1994 and 1991. These cruises were repeated on hydrographic surveys as part of the CLIVAR/CO2 Repeat Hydrography Program on the east-west P2 cruise along 30°N in 2004 and on the north-south P16N cruise along 152°W in 2006. Observed pH decreases and DIC increases on the P16N cruise provides the first direct evidence for ocean acidification in the Pacific Ocean and verify earlier model projections that the oceans are undergoing ocean acidification as a result of the uptake of carbon dioxide from the atmosphere. Based on the carbon measurements on these cruises we have estimated an average upward migration of the aragonite saturation horizon of approximately 1 m yr-1 in the North Pacific. Such shoaling is due to the combined effects of anthropogenic CO2, ventilation and biological respiration processes in the surface and intermediate waters. However, in the northeastern Pacific the upward migration has been significantly greater, with values exceeding 5 m yr-1 in some places. This may be the result of enhanced invasion of colder CO2-rich Subarctic Water at depths between 50 and 150m into the California Current over the last few years.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMOS12B..04F
- Keywords:
-
- 1225 Global change from geodesy (1222;
- 1622;
- 1630;
- 1641;
- 1645;
- 4556);
- 3610 Geochemical modeling (1009;
- 8410);
- 4806 Carbon cycling (0428);
- 4820 Gases