CO2IIM :: CO2 en el océano

Research Background & Fields of Interest

The atmospheric carbon dioxide (CO2) levels have been on the rise since the preindustrial era because of the exponentially increasing anthropogenic activity. The ocean has absorbed about 30% of the anthropogenic CO2, lessening its impact on the climate, but generating “the other CO2 problem” which refers to ocean acidification.

Oceanic acidification surveillance is a special duty for UN Agenda 2030 (SDGs 13.2 and 14.3). They state the needing of observe on global scales in order to understand ocean acidification (OA) and its drivers correctly with the goal of knowing the global status of OA and its implications and have sufficient data to develop predictive skills and early warning systems. In response to that, CSIC have created the interdisciplinary thematic platform (PTI) WATER:iOS (Warming and Acidification Threats on Ecosystem Resources: iOcean Surveillance), bringing together people, skills and expertise from several institutions to contribute to ocean acidification surveillance.

Every year the atmosphere receives 7 Gt (Gt = gigatons = thousands of millions of tons) of carbon derived directly from such human activities (anthropogenic carbon or Cant). Approximately 50% of these atmospheric CO2 emissions remain on the air, while the other half is captured and stored in the oceanic and land biosphere environmental compartments.

The ocean naturally behaves as a CO2 sink by uptaking up to 2 Gt of anthropogenic CO2 per year. Within this scenario, the North Atlantic is one of the grandest CO2 sinks in the global ocean as major water mass formation processes favour the sequestration of CO2 either through mixing or dissolving.

The CO2 uptake capacity of the ocean varies largely depending on the water mass ventilation rhythms. If we aim to ever understand and evaluate the CO2 storage capacity of the present day and future oceans, then a state of the art knowledge and acquaintance of the water mass mixing and formation rates is mandatory through continuous monitoring and evaluation.

Out of the total dissolved inorganic carbon (DIC) in the ocean, the anthropogenic fraction represents 3% of it at maximum. In spite of its apparently modest contribution, this amount suffices to cause severe impact on the oceanic acidity (30% of ion hydrogen increase) and heat content. The fact that anthropogenic CO2 uptake represents such a small fraction of DIC is also one of the major handicaps when it comes to its determination. The CO2 group is continuously assessing and improving the accuracy of the analytical procedures used to measure the seawater carbon system. At present, the following techniques are being applied: spectrophotometric pH determinations, gas-extraction total inorganic carbon (TIC, DIC) determination and total alkalinity measurement through potentiometric titration.

Nitrous oxide (N2O) and methane (CH4) are biologically produced trace gases that exerts a strong climate influence as powerful greenhouse gases which also affect stratospheric ozone depletion (N2O) and the oxidative capacity of the atmosphere (CH4). Because the ocean emits one third of the global N2O natural emissions to the atmosphere, the observations has been targeted mainly toward low oxygen oceanic regions, limited in extension but characterised by intense N2O production. However, the capacity to uptake N2O and its injection into the deep ocean circulation in ventilated regions such as the North Atlantic Ocean and the subpolar gyre have received until now little attention. This knowledge is urgently needed to refine our estimations of the global oceanic N2O budgets.

The main research interests of the CO2 Group at the Vigo Marine Research Institute focus on the following:

  • Study of Ocean Acidification trends and their drivers in the Open Ocean, coastal systems and national parks.
  • Improvement of the analytical and methodological techniques in anthropogenic CO2/N2O estimation.
  • Technological developments for surveillance acidification in coastal systems.
  • Contribution to international evaluation of the global and regional CO2/N2O/CH4 cycle assessment and processes.
  • Development of numerical techniques with neural networks for the study of ocean and coastal acidification.
  • Development of automatic laboratory systems for the observation of the response of marine species to future scenarios.
  • Biogeochemical modeling.
  • Providing value-added services for customers on CO2/N2O/CH4 surveillance:



  • (NDP-106) Broullón, Daniel; Pérez, Fiz F.; Velo, Anton; Hoppema, Mario; Olsen, Are; Takahashi, Taro; Key, Robert M.; Tanhua, Toste; González-Dávila, Melchor; Jeansson, Emil; Kozyr, Alex; Steven M. A. C. van Heuven (2020). A global monthly climatology of total alkalinity (AT): a neural network approach (NCEI Accession 0222470). NOAA National Centers for Environmental Information.







  • Carracedo L.I.; M. Gilcoto; H. Mercier; F.F. Pérez. Seasonal dynamics in the Azores-Gibraltar Strait region : A climatologically-based study. Progress in Oceanography. 122, pp. 116 - 130. 2014.
  • Pardo P.C ; F.F. Pérez; S. Khatiwala; A.F. Ríos. Anthropogenic CO2 estimates in the Southern Ocean: Storage partitioning in the different water masses. Progress in Oceanography. 120, pp. 230 - 242. 2014
  • Zunino, P., Garcia-Ibañez, M. I., Lherminier, P., Mercier, H., Rios, A. F., and Pérez, F. F.: Variability of the transport of anthropogenic CO2 at the Greenland–Portugal OVIDE section: controlling mechanisms, Biogeosciences, 11, 2375-2389, doi:10.5194/bg-11-2375-2014, 2014.
  • Bakker, D. C. E., Pfeil, B., Smith, K., Hankin, S., Olsen, A., Alin, S. R., Cosca, C., Harasawa, S., Kozyr, A., Nojiri, Y., O'Brien, K. M., Schuster, U., Telszewski, M., Tilbrook, B., Wada, C., Akl, J., Barbero, L., Bates, N. R., Boutin, J., Bozec, Y., Cai, W.-J., Castle, R. D., Chavez, F. P., Chen, L., Chierici, M., Currie, K., de Baar, H. J. W., Evans, W., Feely, R. A., Fransson, A., Gao, Z., Hales, B., Hardman-Mountford, N. J., Hoppema, M., Huang, W.-J., Hunt, C. W., Huss, B., Ichikawa, T., Johannessen, T., Jones, E. M., Jones, S. D., Jutterström, S., Kitidis, V., Körtzinger, A., Landschützer, P., Lauvset, S. K., Lefèvre, N., Manke, A. B., Mathis, J. T., Merlivat, L., Metzl, N., Murata, A., Newberger, T., Omar, A. M., Ono, T., Park, G.-H., Paterson, K., Pierrot, D., Ríos, A. F., Sabine, C. L., Saito, S., Salisbury, J., Sarma, V. V. S. S., Schlitzer, R., Sieger, R., Skjelvan, I., Steinhoff, T., Sullivan, K. F., Sun, H., Sutton, A. J., Suzuki, T., Sweeney, C., Takahashi, T., Tjiputra, J., Tsurushima, N., van Heuven, S. M. A. C., Vandemark, D., Vlahos, P., Wallace, D. W. R., Wanninkhof, R., and Watson, A. J.:An update to the Surface Ocean CO<sub>2</sub> Atlas (SOCAT version 2), Earth Syst. Sci. Data, 6, 69-90, doi:10.5194/essd-6-69-2014, 2014.|









  • Castro CG, Nieto–Cid M, Álvarez–Salgado XA, Pérez FF. 2006. Local mineralization patterns in the mesopelagic zone of the Eastern North Atlantic of the NW Iberian Peninsula. Deep Sea Research I, 53:1925–1940.
  • Duarte, C.M., Alonso, S., Benito, G., Dachs, J., Montes, C., Pardo, M., Ríos, A.F., Simó, R., Valladares, F. 2006. Cambio Global. Impacto de la actividad humana sobre el sistema tierra. Colección Divulgación (ISBN: 978-84-00-08452-3). Editorial Consejo Superior de Investigaciones Científicas, Volumen 1: 1-166.


  • Álvarez, M., F.F. Pérez, D.R. Shoosmith and H.L. Bryden. 2005. The unaccounted role of Mediterranean Water in the draw-down of anthropogenic carbon. Journal of Geophysical Research 110: 1-18. doi: 10.1029/2004JC002633.
  • Pérez F.F., C.G. Castro, A.F. Ríos and F. Fraga. 2005. Chemical properties of the deep winter mixed layer in the Northeast Atlantic (40–47ºN). Journal Marine Systems 54: 115–125.
  • Ríos, A.F., F.F. Pérez, M. Álvarez, L. Mintrop, M. González–Dávila, J.M. Santana Casiano, N. Lefèvre and A.J. Watson. 2005. Seasonal sea–surface carbon dioxide in Azores area. Marine Chemistry 96: 35–51.


  • Álvarez M., F.F. Pérez, H. Bryden, A. F. Ríos. 2004. Physical and biogeochemical transport structure in the North Atlantic subpolar gyre. Journal of Geophysical Research 109, C03027 doi: 1 0.1029/2003JC002015.
  • Brea S., X.A. Álvarez-Salgado, M. Álvarez, F.F. Pérez, L. Mémery, H. Mercier, M.J. Messias. 2004. Nutrient mineralization rates and ratios in the Eastern South Atlantic. Journal of Geophysical Research 109, doi: 10.1029/2003JC002051.
  • Lefèvre N., A.J. Watson, A. Olsen, A.F. Ríos, F.F. Pérez T. Johannessen. 2004. A decrease in the sink for atmospheric CO2 in the North Atlantic. Geophysical Research Letters 31, doi: 10.1029/2003GL018957.
  • Sabine C.L., Feely R.A., Gruber N., Key R.M., Lee K., Bullister J.L., Wanninkhof R., Wong C.S., Wallace D.W.R., Tilbrook B., Millero F.J., Peng T.-H., Kozyr A., Ono T., Ríos A.F. 2004. The oceanic sink for anthropogenic CO2. Science 305, 367-371.


  • Álvarez, M, A.F. Ríos, F.F. Pérez, G. Rosón and H.L. Bryden. 2003. Transports and budgets of total inorganic carbon In the subpolar and temperate North Atlantic. Global Biogeochemical Cycles 17(1), 1002–1029.
  • Alvarez–Salgado, X.A., F.G. Figueiras, F.F. Pérez, S. Groom, E. Nogueira, A. Borges, L. Chou, C.G. Castro, G. Moncoiffe, A.F. Ríos, A.E.J. Miller, M. Frankignoulle, G. Savidge, R. Wollast. 2003. The Portugal Coastal Counter Current off NW Spain: new insights on its biogeochemical variability. Progress in Oceanography, 56, 281–321.
  • Gago J., X.A. Alvarez–Salgado, F.F. Pérez, and A.F. Ríos. 2003. Partitioning of physical and biogeochemical contributions to the short–time–scale variability of surface seawater pCO2 in a costal upwelling system: a novel quantitative approach. Marine Ecology Progress Series, 255, 43–54.
  • Pérez, F.F, M. Gilcoto and A.F. Ríos. 2003. Large and mesoscale variability of the water masses and the DCM the Azores Front. Journal Geophysical Research, 108 C7, 3215.
  • Ríos, A.F., Álvarez-Salgado, X.A., Pérez, F.F., Bingler, L.S., Arístegui, J., Mémery, L., 2003. Carbon dioxide along WOCE line A14: Water masses characterization and anthropogenic entry. J. Geophys. Res. 108, 3123, DOI: 10.1029/2000JC000366.
  • Rosón. G. A.F. Ríos, A. Lavín, F.F. Pérez, and H.K. Bryden. 2003. Carbon distributrion and fluxes in the subtropical North Atlantic Ocean (24.5ºN) . Journal Geophysical Research, 108 C5,3144–3158.


  • Álvarez, M., A.F. Ríos, G. Rosón. 2002. Spatio–temporal variability of air–sea carbon dioxide and oxygen fluxes in the Bransfield and Gerlache Straits during austral summer 95–96. Deep–Sea Research II 49, 643–662.
  • Álvarez, M., H.K. Bryden, F.F. Pérez, A.F. Ríos, G. Rosón. 2002. Physical and biogeochemical fluxes and net budgets in the subpolar and temperate north Atlantic. Journal of Marine Research 60, 191–262.
  • Pérez, F.F., M. Álvarez, A.F. Ríos. 2002. Improvements on the back–calculation technique for estimating anthropogenic CO2. Deep–Sea Research I 49, 859–875.


  • Pardo, C.P., M. Gilcoto, F.F. Pérez. 2001.Short–time scale coupling between termohaline and meteorological forcing in the Ría de Pontevedra. Scientia Marina 65 (suppl.1.), 229–240.
  • Pérez F.F., C.G. Castro, X.A. Álvarez–Salgado, A.F. Ríos. 2001. Coupling between the Iberian basin–scale circulation and the Portugal boundary current system. A chemical study. Deep–Sea Research I 48, 1519–1533.
  • Pérez F.F., J. Gago, M. Álvarez, A.F. Ríos. 2001. Temporal variability of atmospheric CO2 of the Spanish Atlantic Coast. Oceanologica Acta 24, 11–18.
  • Pérez, F.F., L. Mintrop, O. Llinás, M. Glez–Dávila, C.G. Castro, M. Álvarez, A. Körtzinger, M. Santana–Casiano, M.J. Rueda, A.F. Ríos. 2001. Mixing analysis of nutrients, oxygen and inorganic carbon in the Canary Islands region. Journal of Marine Systems 28, 183–201.
  • Ríos, A.F., F.F. Pérez, F. Fraga. 2001. Long–term (1977–1997) measurements of carbon dioxide in the Eastern North Atlantic: evaluation of anthropogenic input. Deep–Sea Research II 48, 2227–2239.


  • Castro C.G., F.F. Pérez, X. A. Álvarez–Salgado, F. Fraga, 2000. Coupling between the thermohaline, chemical and biological fields during two contrasting upwelling events off the NW Iberian Peninsula (Galician Coast). Continental Shelf Research 20, 189–210.
  • Mémery, L., M. Arhan, X.A. Álvarez–Salgado, M.–J. Messias, H. Mercier, G.C. Castro, A.F. Ríos, 2000. The water masses along the western boundary of the south and equatorial Atlantic. Progress in Oceanography 47, 69–98.
  • Mintrop L., F.F. Pérez, M. González–Davila, J. M. Santana–Casiano, A. Körtzinger, 2000. Alkalinity determination by potentiometry – intercalibration using three different methods. Ciencia Marina 26, 23–27.
  • Pérez, F.F., X.A. Álvarez–Salgado, G. Rosón, 2000. Stoichiometry of net ecosystem metabolism in coastal inlet affected by upwelling. The Ría de Arousa (NW Spain). Marine Chemistry 69, 217–236.
  • Pérez, F.F., A.F. Ríos, T. Rellán, M. Alvarez, 2000. Improvements in potentiometric seawater alkalinity determination. Ciencia Marina 26, 463–478.
  • Pérez, F.F., R.T. Pollard, J.R. Read, V. Valencia, J,.M. Cabanas, A.F. Ríos, 2000. Climatological coupling of the termohaline decadal change in Central Water of the Eastern North Atlantic. Scientia Marina, 64, 347–353.

Doctoral Theses

Transport and Budget of Carbon, Nutrients and Oxygen In the North Atlantic

Marcos Morente Fontela

Universidade de Vigo, Marzo 2018.

Spatiotemporal variability of the carbonate system in the North Atlantic Ocean

Elisa Fernandez Guallart

Universidad de las Palmas de Gran Canaria. Febrero 2016.

Acidification and transports of water masses and CO2 in the North Atlantic

Maribel García Ibáñez

Facultad de Ciencias del Mar - Universidade de Vigo, 2015.

CO2 flux variability in the Galician and Californian upwelling systems

Alba Marina Cobo-Viveros

Facultad de Ciencias del Mar - Universidade de Vigo, 2015.

Optimización de métodos numéricos en la determinación de la acidificación en los océanos

Antón Velo Lanchas

Facultad de Ciencias del Mar - Universidade de Vigo, 2014

Subtropical North-East Atlantic water masses and transports

Lidia Carracedo Segade

Facultad de Ciencias del Mar - Universidade de Vigo, 2013

El CO2 antrópico en el Océano Austral

Paula Conde Pardo

Facultad de Ciencias del Mar - Universidade de Vigo, 2013

Temporal changes in natural and anthropogenic CO2 in the North Atlantic Ocean

Noelia Maria Fajar González

Universidade de Santiago de Compostela, 2013

CO2 antropogénico en el Atlántico

Marcos Vázquez Rodríguez

Facultad de Ciencias del Mar - Universidade de Vigo, 2009

Variabilidad de la presión de CO2 superficial en el Atlántico Norte

Xosé Antonio Padín

Facultad de Ciencias del Mar - Universidade de Vigo, 2009

Ciclo de la materia orgánica disuelta en un sistema de afloramiento costero

Mar Nieto Cid

Facultad de Ciencias del Mar - Universidade de Vigo, 2005.

Patrones de variabildad termohalina en la Ría de Vigo

Miguel Gil Coto

Facultad de Ciencias del Mar - Universidade de Vigo, 2004.

Descripción dinámica de la circulación en dos Rías Baixas: Vigo y Pontevedra

Belén Martín Míguez

Facultad de Ciencias del Mar - Universidade de Vigo, 2003.

Water masses and transports of physical and chemical properties in the Subpolar North Atlantic Gyre

Marta Alvarez Rodríguez

Facultad de Ciencias del Mar - Universidade de Vigo, 2002.

Transformaciones biogeoquímicas y flujos de carbono en la Ría de Vigo. Estudio de la variación estacional y de corta escala

Jesus Gago Piñeiro

Facultad de Ciencias del Mar - Universidade de Vigo, 2000.

Predicción numérica y contraste experimental de la circulación en la Ría de Vigo

Carlos Alberto Souto Torres

Facultad de Ciencias del Mar - Universidade de Vigo, 2000.

Current Projects


In-Memoriam Aída Fernández Ríos (Dra.) - Profesor de Investigación - Sistema del CO2 - Masas de agua - Estequiometría

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