Oceanography The Official Magazine of
The Oceanography Society
Volume 27 Issue 01

View Issue TOC
Volume 27, No. 1
Pages 126 - 141

OpenAccess

A Time-Series View of Changing Ocean Chemistry Due to Ocean Uptake of Anthropogenic CO2 and Ocean Acidification

By Nicholas R. Bates , Yrene M. Astor , Matthew J. Church , Kim Currie, John E. Dore, Melchor González-Dávila, Laura Lorenzoni, Frank Muller-Karger, Jon Olafsson, and J. Magdalena Santana-Casiano 
Jump to
Article Abstract Citation Supplementary Materials References Copyright & Usage
Article Abstract

Sustained observations provide critically needed data and understanding not only about ocean warming and water cycle reorganization (e.g., salinity changes), ocean eutrophication, and ocean deoxygenation, but also about changes in ocean chemistry. As an example of changes in the global ocean carbon cycle, consistent changes in surface seawater CO2-carbonate chemistry are documented by seven independent CO2 time series that provide sustained ocean observations collected for periods from 15 to 30 years: (1) Iceland Sea, (2) Irminger Sea, (3) Bermuda Atlantic Time-series Study (BATS), (4) European Station for Time series in the Ocean at the Canary Islands (ESTOC), (5) CArbon Retention In A Colored Ocean sites in the North Atlantic (CARIACO), (6) Hawaii Ocean Time-series (HOT), and (7) Munida in the Pacific Ocean. These ocean time-series sites exhibit very consistent changes in surface ocean chemistry that reflect the impact of uptake of anthropogenic CO2 and ocean acidification. The article discusses the long-term changes in dissolved inorganic carbon (DIC), salinity-normalized DIC, and surface seawater pCO2 (partial pressure of CO2) due to the uptake of anthropogenic CO2 and its impact on the ocean’s buffering capacity. In addition, we evaluate changes in seawater chemistry that are due to ocean acidification and its impact on pH and saturation states for biogenic calcium carbonate minerals.

Citation

Bates, N.R., Y.M. Astor, M.J. Church, K. Currie, J.E. Dore, M. González-Dávila, L. Lorenzoni, F. Muller-Karger, J. Olafsson, and J.M. Santana-Casiano. 2014. A time-series view of changing ocean chemistry due to ocean uptake of anthropogenic CO2 and ocean acidification. Oceanography 27(1):126–141, https://doi.org/10.5670/oceanog.2014.16.

Supplementary Materials

Supplementary Table S1 (74 KB pdf)

References
    Andersson, A.J., F.T. Mackenzie, and N.R. Bates. 2008. Life on the margin: Implications of ocean acidification on Mg-calcite, high latitude and cold-water marine calcifiers. Marine Ecology Progress Series 373:265–273, https://doi.org/10.3354/meps07639.
  1. Astor, Y.M., L. Lorenzoni, R. Thunell, R. Varela, F. Muller-Karger, L. Troccoli, G.T. Taylor, M.I. Scranton, E. Tappa, and D. Rueda. 2013. Interannual variability in sea surface temperature and fCO2 changes in the Cariaco Basin. Deep Sea Research Part II 93:33–43, https://doi.org/10.1016/j.dsr2.2013.01.002.
  2. Astor, Y.M., M.I. Scranton, F. Muller-Karger, R. Bohrer, and J. García. 2005. fCO2 variability at the CARIACO tropical upwelling time series station. Marine Chemistry 97:245–261, https://doi.org/10.1016/j.marchem.2005.04.001.
  3. Bakker, D.C.E., B. Pfeil, K. Smith, S. Hankin, A. Olsen, S. R. Alin, C. Cosca, B. Hales, S. Harasawa, A. Kozyr, and others. 2013. An update to the surface ocean carbon atlas (SOCAT version 2). Earth System Science Data Discussions 6:465–512, https://doi.org/10.5194/essdd-6-465-2013.
  4. Bates, N.R. 2001. Interannual variability of oceanic CO2 and biogeochemical properties in the Western North Atlantic subtropical gyre. Deep Sea Research Part II 48:1,507–1,528, https://doi.org/10.1016/S0967-0645(00)00151-X.
  5. Bates, N.R. 2007. Interannual variability of the oceanic CO2 sink in the subtropical gyre of the North Atlantic Ocean over the last two decades. Journal of Geophysical Research 112, C09013, https://doi.org/10.1029/2006JC003759.
  6. Bates, N.R. 2012. Multi-decadal uptake of carbon dioxide into subtropical mode waters of the North Atlantic Ocean. Biogeosciences 9:2,649–2,659, https://doi.org/10.5194/bg-9-2649-2012.
  7. Bates, N.R., M.H.P. Best, K. Neely, R. Garley, A.G. Dickson, and R.J. Johnson. 2012. Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean. Biogeosciences 9:2,509-2,522, https://doi.org/10.5194/bg-9-2509-2012.
  8. Bates, N.R., J.T. Mathis, and L. Cooper. 2009. Ocean acidification and biologically induced seasonality of carbonate mineral saturation states in the western Arctic Ocean. Journal of Geophysical Research 114, C11007, https://doi.org/10.1029/2008JC004862.
  9. Bates, N.R., A.F. Michaels, and A.H. Knap. 1996. Seasonal and interannual variability of oceanic carbon dioxide species at the US JGOFS Bermuda Atlantic Time-series Study (BATS) site. Deep Sea Research Part II 43:347–383, https://doi.org/10.1016/0967-0645(95)00093-3. Corrigendum: 43:1,435–1,435.
  10. Bates, N.R., M.I. Orchowska, R. Garley, and J.T. Mathis. 2013. Summertime calcium carbonate undersaturation in shelf waters of the western Arctic Ocean – How biological processes exacerbate the impact of ocean acidification. Biogeosciences 10:5,281–5,309, https://doi.org/10.5194/bg-10-5281-2013.
  11. Bates, N.R., A.C. Pequignet, R.J. Johnson, and N. Gruber. 2002. A short-term sink for atmospheric CO2 in subtropical mode water of the North Atlantic Ocean. Nature 420:489–493, https://doi.org/10.1038/nature01253.
  12. Brewer, P.G., J.L. Sarmiento, and W.M. Smethie. 1985. The Transient Tracers in the Ocean (TTO) program: The North Atlantic Study, 1981; The Tropical Atlantic Study, 1983. Journal of Geophysical Research 90:6,903–6,905, https://doi.org/10.1029/JC090iC04p06903.
  13. Brix, H., K.I. Currie, and S.E. Mikaloff Fletcher. 2013. Seasonal variability of the carbon cycle in subantarctic surface water in the South West Pacific. Global Biogeochemical Cycles 27:1–12, https://doi.org/10.1002/gbc.20023.
  14. Byrne, R.H., S. Mecking, R.A. Feely, and X. Liu. 2010. Direct observations of basin-wide acidification of the North Pacific Ocean. Geophysical Research Letters 37, L02601, https://doi.org/10.1029/2009GL040999.

  15. Caldeira, K., and M.W. Wickett. 2003. Anthropogenic carbon and ocean pH. Nature 425:365–368, https://doi.org/10.1038/425365a.
  16. Church, M.J., M.W. Lomas, and F. Muller-Karger. 2013. Sea change: Charting the course for biogeochemical ocean time-series research in a new millennium. Deep Sea Research Part II 93:2–15, https://doi.org/10.1016/j.dsr2.2013.01.035.

  17. Currie, K.I., M.R. Reid, and K.A. Hunter. 2011. Interannual variability of carbon dioxide drawdown by subantarctic surface water near New Zealand. Biogeochemistry 104:23–34, https://doi.org/10.1007/s10533-009-9355-3.

  18. Dickson, A.G., and F.J. Millero. 1987. A Comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media. Deep Sea Research Part A 34:1,733–1,743, https://doi.org/10.1016/0198-0149(87)90021-5.

  19. Dickson, A.G., C.L. Sabine, and J.R. Christian. 2007. Guide to Best Practices for Ocean CO2 Measurements. Sidney, British Columbia, North Pacific Marine Science Organization, PICES Special Publication 3.
  20. Doney, S.C., V.J. Fabry, R.A. Feely, and J.A. Kleypas. 2009. Ocean acidification: The other CO2 problem. Annual Review of Marine Science 1:169-192, https://doi.org/10.1146/annurev.marine.010908.163834.

  21. Dore, J.E., R. Lukas, D.W. Sadler, M.J. Church, and D.M. Karl. 2009. Physical and biogeochemical modulation of ocean acidification in the central North Pacific. Proceedings of the National Academy of Sciences of the United States of America 106:12,235–12,240, https://doi.org/10.1073/pnas.0906044106.

  22. Dore, J.E., R. Lukas, D.W. Sadler, and D.M. Karl. 2003. Climate-driven change to the atmospheric CO2 sink in the subtropical North Pacific Ocean. Nature 424:754–757, https://doi.org/10.1038/nature01885.

  23. Egleston, E.S., C.L. Sabine, and F.M.M. Morel. 2010. Revelle revisited: Buffer factors that quantify the response of ocean chemistry to changes in DIC and alkalinity. Global Biogeochemical Cycles 24, GB1002, https://doi.org/10.1029/2008GB003407.

  24. Feely, R.A., R.H. Byrne, J.G. Acker, P.R. Betzer, C.-T.A. Chen, J.F. Gendron, and M.F. Lamb. 1988. Winter-summer variations of calcite and aragonite saturation in the northeast Pacific. Marine Chemistry 25:227–241, https://doi.org/10.1016/0304-4203(88)90052-7.

  25. Feely, R.A., C.L. Sabine, J.M. Hernandez-Ayon, D. Ianson, and B. Hales. 2008. Evidence for upwelling of corrosive “acidified” water onto the continental shelf. Science 320:1,490–1,492, https://doi.org/10.1126/science.1155676.

  26. Feely, R.A., T. Takahashi, R. Wanninkhof, M.J. McPhaden, C.E. Cosca, S.C. Sutherland, and M.E. Carr. 2006. Decadal variability of the air-sea CO2 fluxes in the equatorial Pacific Ocean. Journal of Geophysical Research 111, C08S90, https://doi.org/10.1029/2005JC003129.

  27. Feely, R.A., R. Wanninkhof, C.E. Cosca, M.J. McPhaden, R.H. Byrne, F.J. Millero, F.P. Chavez, T. Clayton, D.M. Campbell, and P.P. Murphy. 1994. The effect of tropical instability waves on CO2 species distributions along the equator in the Eastern Equatorial Pacific during the 1992 ENSO event. Geophysical Research Letters 21:277–280, https://doi.org/10.1029/93GL03212.

  28. Feely, R.A., R. Wanninkhof, T. Takahashi, and P. Tans. 1999. Influence of El Niño on the equatorial Pacific contribution to atmospheric CO2 accumulation. Nature 398:597–601, https://doi.org/10.1038/19273.
  29. Gattuso, J.-P., and L. Hansson, eds. 2011. Ocean Acidification, Oxford University Press, 352 pp.
  30. González-Dávila, M., J.M. Santana-Casiano, and E.F. González-Dávila. 2007. Interannual variability of the upper ocean carbon cycle in the northeast Atlantic Ocean. Geophysical Research Letters 34, L07608, https://doi.org/10.1029/2006GL028145.
  31. González-Dávila, M., J.M. Santana-Casiano, M.J. Rueda, and O. Llinas. 2010. The water column distribution of carbonate system variables at the ESTOC site from 1995 to 2004. Biogeosciences 7:3,067–3,081, https://doi.org/10.5194/bg-7-3067-2010.
  32. Gruber, N., C.D. Keeling, and N.R. Bates. 2002. Interannual variability in the North Atlantic Ocean carbon sink. Science 298:2,374–2,378, https://doi.org/10.1126/science.1077077.
  33. Ishii, M., N. Kosugi, D. Sasano, S. Saito, T. Midorikawa, and H.Y. Inoue. 2011. Ocean acidification off the south coast of Japan: A result from time series observations of CO2 parameters from 1994 to 2008. Journal of Geophysical Research 116, C06022, https://doi.org/10.1029/2010jc006831.
  34. Johnson, K.M., J.M. Sieburth, P.J.L. Williams, and L. Brandstrom. 1987. Couolometric total carbon dioxide analysis for marine studies: Automation and calibration. Marine Chemistry 21:117–133, https://doi.org/10.1016/0304-4203(87)90033-8.
  35. Johnson, K.M., K.D. Wills, D.B. Butler, W.K. Johnson, and C.S. Wong. 1993. Couolometric total carbon dioxide analysis for marine studies: Maximizing the performance of an automated gas extraction system and coulometric detector. Marine Chemistry 44:167–187, https://doi.org/10.1016/0304-4203(93)90201-X.
  36. Key, R.M., A. Kozyr, C.L. Sabine, K. Lee, R. Wanninkhof, J.L. Bullister, R.A. Feely, F.J. Millero, C. Mordy, and T.H. Peng. 2004. A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP). Global Biogeochemical Cycles 18, GB4031, https://doi.org/10.1029/2004GB002247.
  37. Levine, N.M., S.C. Doney, I. Lima, R. Wanninkhof, C.L. Sabine, R.A. Feely, and N.R. Bates. 2011. The impact of interannual variability on the uptake and accumulation of anthropogenic CO2 in the North Atlantic. Global Biogeochemical Cycles 25, GB3022, https://doi.org/10.1029/2010GB003892.
  38. Lorenzoni, L., G.T. Taylor, C. Benitez-Nelson, D. Hansell, R. Masserini, E. Montes, K. Fanning, R. Varela, Y. Astor, L. Guzmán, and F.E. Muller-Karger. 2013. Spatial and seasonal variability of dissolved organic matter in the Cariaco Basin. Journal of Geophysical Research 118:951–962, https://doi.org/10.1002/jgrg.20075.
  39. McGrath, T., C. Kivimäe, T. Tanhua, R.R. Cave, and E. McGovern. 2012. Inorganic carbon and pH levels in the Rockall Trough 1991–2010. Deep Sea Research Part I 68:79–91, https://doi.org/10.1016/j.dsr.2012.05.011.
  40. McKinley, G.A., A.R. Fay, T. Takahashi, and N. Metzl. 2011. Convergence of atmospheric and North Atlantic carbon dioxide trends on multidecadal timescales. Nature Geoscience 4:606–610, https://doi.org/10.1038/Ngeo1193.
  41. McKinley, G.A., M.J. Follows, and J. Marshall. 2004. Mechanisms of air-sea CO2 flux variability in the equatorial Pacific and the North Atlantic. Global Biogeochemical Cycles 18, GB2011, https://doi.org/10.1029/2003gb002179.
  42. McKinley, G.A., T. Takahashi, E. Buitenhuis, F. Chai, J.R. Christian, S.C. Doney, M.S. Jiang, K. Lindsay, J.K. Moore, C. Le Quere, and others. 2006. North Pacific carbon cycle response to climate variability on seasonal to decadal timescales. Journal of Geophysical Research 111, C07506, https://doi.org/10.1029/2005JC003173.
  43. Mehrbach, C., C.H. Culberson, J.E. Hawley, and R.M. Pytkowicz. 1973. Measurement of the apparent dissociation constants of carbonic acid in seawater at atmospheric pressure. Limnology & Oceanography 18:897–907.
  44. Menzel, D.W., and J. Ryther. 1964. The composition of particulate organic matter in the western North Atlantic. Limnology & Oceanography 9:179–186.
  45. Midorikawa, T., M. Ishii, N. Kosugi, D. Sasano, T. Nakano, S. Saito, N. Sakamoto, H. Nakano, and H.Y. Inoue. 2012. Recent deceleration of oceanic pCO2 increase in the western North Pacific in winter. Geophysical Research Letters 39, L12601, https://doi.org/10.1029/2012gl051665.
  46. Midorikawa, T., K. Nemoto, H. Kamiya, M. Ishii, and H.Y. Inoue. 2005. Persistently strong oceanic CO2 sink in the western subtropical North Pacific. Geophysical Research Letters 32, L05612, https://doi.org/10.1029/2004gl021952.
  47. Muller-Karger, F.E., R. Varela, R.C. Thunell, M.I. Scranton, G.T. Taylor, Y. Astor, C.R. Benitez-Nelson, L. Lorenzoni, E. Tappa, M.A. Goñi, and others. 2010. The CARIACO Oceanographic Time Series. Pp. 454–464 in Carbon and Nutrient Fluxes in Continental Margins: A Global Synthesis. JGOFS Continental Margins Task Team (CMTT). K.-K. Liu, L. Atkinson, R. Quinones, and L. Talaue-McManus, eds, Springer-Verlag, Berlin/Heidelberg.
  48. Olafsson, J., S.R. Olafsdottir, A. Benoit-Cattin, M. Danielsen, T.S. Arnarson, and T. Takahashi. 2009. Rate of Iceland Sea acidification from time series measurements. Biogeosciences 6:2,661–2,668, https://doi.org/10.5194/bg-6-2661-2009.
  49. Olafsson, J., S.R. Olafsdottir, A. Benoit-Cattin, and T. Takahashi. 2010. The Irminger Sea and the Iceland Sea time series measurements of sea water carbon and nutrient chemistry 1983–2006. Earth System Science Data 2:99–104, https://doi.org/10.5194/essd-2-99-2010.
  50. Olsen, A., R.G.J. Bellerby, T. Johannessen, A.M. Omar, and I. Skjelvan. 2003. Interannual variability in the wintertime air-sea flux of carbon dioxide in the northern North Atlantic, 1981–2001. Deep Sea Research Part I 50:1,323–1,338, https://doi.org/10.1016/S0967-0637(03)00144-4.
  51. Revelle, R., and H.E. Suess. 1957. Carbon dioxide exchange between atmosphere and ocean and the question of an increase of atmospheric CO2 during the past decades. Tellus 9:18–27, https://doi.org/10.1111/j.2153-3490.1957.tb01849.x.
  52. Robbins, L.L., M.E. Hansen, J.A. Kleypas, and S.C. Meylan. 2010. CO2calc: A user-friendly seawater carbon calculator for Windows, Mac OS X, and iOS (iPhone). US Geological Survey Open-File Report, 2010–1280, 17 pp. Available online at: http://pubs.usgs.gov/of/2010/1280 (accessed December 3, 2013).
  53. Rödenbeck, C., R.F. Keeling, D.C.E. Bakker, N. Metzl, A. Olsen, C. Sabine, and M. Heimann. 2013. Global surface-ocean pCO2 and sea–air CO2 flux variability from an observation-driven ocean mixed-layer scheme. Ocean Science 9:193–216, https://doi.org/10.5194/os-9-193-2013.
  54. Sabine, C.L., R.A. Feely, Y.W. Watanabe, and M. Lamb. 2004. Temporal evolution of the North Pacific CO2 uptake rate. Journal of Oceanography 60:5–15, https://doi.org/10.1023/B:JOCE.0000038315.23875.ae.
  55. Sabine, C.L., R.M. Key, A. Kozyr, R.A. Feely, R. Wanninkhof, F. Millero, T.H. Peng, J. Bullister, and K. Lee. 2005. Global Ocean data analysis project (GLODAP): Results and data. ORNL/CDIAC, Oak Ridge, Tennessee, USA, NDP-083.
  56. Sabine, C.L., and T. Tanhua. 2010. Estimation of anthropogenic CO2 inventories in the ocean. Annual Review of Marine Science 2:175–198, https://doi.org/10.1146/annurev-marine-120308-080947.
  57. Santana-Casiano, J.M., M. González-Dávila, M.J. Rueda, O. Llinás, and E.F. González-Dávila. 2007. The interannual variability of oceanic CO2 parameters in the northeast Atlantic subtropical gyre at the ESTOC site. Global Biogeochemical Cycles 21, GB1015, https://doi.org/10.1029/2006GB002788.
  58. Schuster, U., G.A. McKinley, N. Bates, F. Chevallier, S.C. Doney, A.R. Fay, M. González-Dávila, N. Gruber, S. Jones, J. Krijnen, and others. 2013. An assessment of the Atlantic and Arctic sea–air CO2 fluxes, 1990–2009. Biogeosciences 10:607–627, https://doi.org/10.5194/bg-10-607-2013.
  59. Schuster, U., and A.J. Watson. 2007. A variable and decreasing sink for atmospheric CO2 in the North Atlantic. Journal of Geophysical Research 112, C11006, https://doi.org/10.1029/2006JC003941.
  60. Skjelvan, I., E. Falck, F. Rey, and S.B. Kringstad. 2008. Inorganic carbon time series at Ocean Weather Station M in the Norwegian Sea. Biogeosciences 5:549–560, https://doi.org/10.5194/bg-5-549-2008.

  61. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller, eds. 2007. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007. Cambridge University Press, Cambridge, UK and New York, NY, USA. Available online at: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html (accessed December 4, 2013).
  62. Steinberg, D.K, C.A. Carlson, N.R. Bates, R.J. Johnson, A.F. Michaels, and A.H. Knap. 2001. Overview of the US JGOFS Bermuda Atlantic Time-series Study (BATS): A decade-scale look at ocean biology and biogeochemistry. Deep-Sea Research Part II 48:1,405–1,447, https://doi.org/10.1016/S0967-0645(00)00148-X.
  63. Suzuki, T., M. Ishii, M. Aoyama, J.R. Christian, K. Enyo, T. Kawano, R.M. Key, N. Kosugi, A. Kozyr, L.A. Miller, and others. 2013. PACIFICA Data Synthesis Project. ORNL/CDIAC-159, NDP-092. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, TN. Available online at: https://doi.org/10.3334/CDIAC/OTG.PACIFICA_NDP092 (accessed December 4, 2013).
  64. Takahashi, T., J. Olafsson, J.G. Goddard, D.W. Chipman, and S.G. Sutherland. 1993. Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: A comparative study. Global Biogeochemical Cycles 7:843–878. https://doi.org/10.1029/93GB02263.

  65. Takahashi, T., S.C. Sutherland, R. Wanninkhof, C. Sweeney, R.A. Feely, D.W. Chipman, B. Hales, G. Friederich, F. Chavez, C. Sabine, and others. 2009. Climatological mean and decadal change in surface ocean pCO2, and net sea-air CO2 flux over the global oceans. Deep Sea Research Part II 56:554–577, https://doi.org/10.1016/j.dsr2.2008.12.009.
  66. Takahashi, T., R.T. Williams, and D.L. Bos. 1982. Carbonate chemistry. Pp. 77–83 in GEOSECS Pacific Expedition, vol. 3, Hydrographic Data 1973–1974. W.S. Broecker, D.S. Spencer, and H. Craig, eds, National Science Foundation, Washington, DC.

  67. Tanhua, T., N.R. Bates, A. Kortzinger, J. Gould, and J. Church. 2013. The marine carbon cycle and anthropogenic carbon ocean inventories. Pp. 787–816 in Ocean Circulation and Climate: A 21st Century Perspective, vol. 103, 2nd edition. G. Seidler, S.M. Griffies, J. Gould, and J.A. Church, eds, Academic Press.
  68. Taylor, G.T., F.E. Muller-Karger, R.C. Thunell, M.I. Scranton, Y. Astor, R. Varela, L. Troccoli Ghinaglia, L. Lorenzoni, K.A. Fanning, S. Hameed, and O. Doherty. 2012. Ecosystem responses in the southern Caribbean Sea to global climate change. Proceedings of the National Academy of Sciences of the United States of America 109:19,315–19,320, https://doi.org/10.1073/pnas.1207514109.
  69. Thomas, H., A.E.F Prowse, S. van Heuven, Y. Bozec, H.J.W. de Baar, L.S. Schiettecatte, K. Suykens, M. Kone, A.V. Borges, I.D. Lima, and S.C. Doney. 2007. Rapid decline of the CO2 buffering capacity in the North Sea and implications for the North Atlantic Ocean. Global Biogeochemical Cycles 21, GB4001, https://doi.org/10.1029/2006GB002825.
  70. Touratier, F., and C. Goyet. 2009. Decadal evolution of anthropogenic CO2 in the northwestern Mediterranean Sea from the mid-1990s to the mid-2000s. Deep Sea Research Part I 56:1,708–1,716, https://doi.org/10.1016/j.dsr.2009.05.015.
  71. van Heuven, S.M.A.C., M. Hoppema, O. Huhn, H.A. Slagter, and H.J.W. de Baar. 2011. Direct observation of increasing CO2 in the Weddell Gyre along the Prime Meridian during 1973–2008. Deep Sea Research Part II 58:2,613–2,635, https://doi.org/10.1016/j.dsr2.2011.08.007.
  72. Wakita, M., S. Watanabe, Y.W. Watanabe, T. Ono, N. Tsurushima, and S. Tsunogai. 2005. Temporal change of dissolved inorganic carbon in the subsurface water at Station KNOT (44°N, 155°E) in the western North Pacific subpolar region. Journal of Oceanography 61:129–139, https://doi.org/10.1007/s10872-005-0026-2.
  73. Watanabe, Y.W., T. Chiba, and T. Tanaka. 2011. Recent change in the oceanic uptake rate of anthropogenic carbon in the North Pacific subpolar region determined by using a carbon-13 time series. Journal of Geophysical Research 116, C02006, https://doi.org/10.1029/2010jc006199.
  74. Watson, A.J., U. Schuster, D.C.E. Bakker, N.R. Bates, A. Corbiere, M. González-Dávila, T. Friedrich, J. Hauck, C. Heinze, T. Johannessen, and others. 2009 Tracking the variable North Atlantic sink for atmospheric CO2. Science 326:1,391–1,393, https://doi.org/10.1126/science.1177394.
  75. Wiltshire, K.H., A. Kraberg, I. Bartsch, M. Boersma, H.D. Franke, J. Freund, C. Gebuhr, G. Gerdts, L. Stockmann, and A. Wichels. 2010. Helgoland Roads, North Sea: 45 years of change. Estuaries and Coasts 33:295–310, https://doi.org/10.1007/s12237-009-9228-y.
  76. Winn, C.D., F.T. Mackenzie, C.J. Carrilo, C.L. Sabine, and D.M. Karl. 1994. Air-sea carbon dioxide exchange in the North Pacific Subtropical Gyre: Implications for the global carbon budget. Global Biogeochemical Cycles 8:157–163, https://doi.org/10.1029/94GB00387.
  77. Wong, C.S., J.R. Christian, S.K.E. Wong, J. Page, L.S. Xie, and S. Johannessen. 2010. Carbon dioxide in surface seawater of the eastern North Pacific Ocean (Line P), 1973–2005. Deep Sea Research Part I 57:687–695, https://doi.org/10.1016/j.dsr.2010.02.003.
  78. Zeebe, R., and D. Wolf-Gladrow. 2001. CO2 in Seawater: Equilibrium, Kinetics, Isotopes. Elsevier Oceanography Series, 65, 346 pp.
Copyright & Usage

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.