Abstract
In the coming decades and centuries, the ocean’s biogeochemical cycles and ecosystems will become increasingly stressed by at least three independent factors. Rising temperatures, ocean acidification and ocean deoxygenation will cause substantial changes in the physical, chemical and biological environment, which will then affect the ocean’s biogeochemical cycles and ecosystems in ways that we are only beginning to fathom. Ocean warming will not only affect organisms and biogeochemical cycles directly, but will also increase upper ocean stratification. The changes in the ocean’s carbonate chemistry induced by the uptake of anthropogenic carbon dioxide (CO2) (i.e. ocean acidification) will probably affect many organisms and processes, although in ways that are currently not well understood. Ocean deoxygenation, i.e. the loss of dissolved oxygen (O2) from the ocean, is bound to occur in a warming and more stratified ocean, causing stress to macro-organisms that critically depend on sufficient levels of oxygen. These three stressors—warming, acidification and deoxygenation—will tend to operate globally, although with distinct regional differences. The impacts of ocean acidification tend to be strongest in the high latitudes, whereas the low-oxygen regions of the low latitudes are most vulnerable to ocean deoxygenation. Specific regions, such as the eastern boundary upwelling systems, will be strongly affected by all three stressors, making them potential hotspots for change. Of additional concern are synergistic effects, such as ocean acidification-induced changes in the type and magnitude of the organic matter exported to the ocean’s interior, which then might cause substantial changes in the oxygen concentration there. Ocean warming, acidification and deoxygenation are essentially irreversible on centennial time scales, i.e. once these changes have occurred, it will take centuries for the ocean to recover. With the emission of CO2 being the primary driver behind all three stressors, the primary mitigation strategy is to reduce these emissions.
References
- 1
German Advisory Council on Global Change. 2006 The future oceans: warming up, rising high, turning sour Berlin, Germany WBGU. Google Scholar
- 2
Keeling R. F., Kortzinger A.& Gruber N. . 2010 Ocean deoxygenation in a warming world. Annu. Rev. Mar. Sci. 2, 199-229doi:10.1146/annurev.marine.010908.163855 (doi:10.1146/annurev.marine.010908.163855). Crossref, PubMed, ISI, Google Scholar - 3
Levitus S., Antonov J.& Boyer T. . 2005 Warming of the world ocean. Geophys. Res. Lett. 32, L02604 doi:10.1029/2004GL021592 (doi:10.1029/2004GL021592). Crossref, ISI, Google Scholar - 4
Lyman J. M., Good S. A., Gouretski V. V., Ishii M., Johnson G. C., Palmer M. D., Smith D. M.& Willis J. K. . 2010 Robust warming of the global upper ocean. Nature 465, 334-337doi:10.1038/nature09043 (doi:10.1038/nature09043). Crossref, PubMed, ISI, Google Scholar - 5
Trenberth K. E., 2007 Observations: surface and atmospheric climate change. Climate change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Solomon S., Qin D., Manning M., Chen Z., Marquis M., Averyt K., Tignor M.& Miller H. Cambridge, UK Cambridge University Press. Google Scholar - 6
Key R. M., 2004 A global ocean carbon climatology: results from the Global Data Analysis Project (GLODAP). Global Biogeochem. Cycles 18, GB4031 doi:10.1029/2004GB002247 (doi:10.1029/2004GB002247). Crossref, ISI, Google Scholar - 7
Garcia H. E., Locarnini R. A., Boyer T. P.& Antonov J. I. . 2006 World ocean atlas 2005. Vol. 4. Nutrients (phosphate, nitrate, silicate). NOAA Atlas Nesdis 64& Levitus S. 396 Washington, DC US Government Printing Office. Google Scholar - 8
Bopp L., Monfray P., Aumont O., Dufresne J.-L., Treut H. L., Madec G., Terray L.& Orr J. C. . 2001 Potential impact of climate change on marine export production. Global Biogeochem. Cycles 15, 81-99doi:10.1029/1999GB001256 (doi:10.1029/1999GB001256). Crossref, ISI, Google Scholar - 9
Steinacher M., 2010 Projected 21st century decrease in marine productivity: a multi-model analysis. Biogeosciences 7, 979-1005doi:10.5194/bg-7-979-2010 (doi:10.5194/bg-7-979-2010). Crossref, ISI, Google Scholar - 10
Marinov I., Doney S. C.& Lima I. D. . 2010 Response of ocean phytoplankton community structure to climate change over the 21st century: partitioning the effect of nutrients, temperature and light. Biogeosciences 7, 3941-3959doi:10.5194/bg-7-3941-2010 (doi:10.5194/bg-7-3941-2010). Crossref, ISI, Google Scholar - 11
Sarmiento J. L., Hughes T. M. C., Stouffer R. J.& Manabe S. . 1998 Simulated response of the ocean carbon cycle to anthropogenic climate warming. Nature 393, 245-249doi:10.1038/30455 (doi:10.1038/30455). Crossref, ISI, Google Scholar - 12
Caldeira K.& Wickett M. E. . 2003 Anthropogenic carbon and ocean pH. Nature 425, 365 doi:10.1038/425365a (doi:10.1038/425365a). Crossref, PubMed, ISI, Google Scholar - 13
Orr J. C., 2005 Aragonite undersaturation in the high-latitude surface ocean within the 21st century. Nature 437, 681-686doi:10.1038/nature04095 (doi:10.1038/nature04095). Crossref, PubMed, ISI, Google Scholar - 14
Sabine C. L., 2004 The oceanic sink for anthropogenic CO2. Science 305, 367-371doi:10.1126/science.1097403 (doi:10.1126/science.1097403). Crossref, PubMed, ISI, Google Scholar - 15
Meinshausen M., Meinshausen N., Hare W., Raper S. C. B., Frieler K., Knutti R., Frame D. J.& Allen M. R. . 2009 Greenhouse-gas emission targets for limiting global warming to 2°C. Nature 458, 1158-1162doi:10.1038/nature08017 (doi:10.1038/nature08017). Crossref, PubMed, ISI, Google Scholar - 16
Sarmiento J. L.& Gruber N. . 2006 Ocean biogeochemical dynamics Princeton, NJ Princeton University Press. Crossref, Google Scholar - 17
Plattner G.-K., Joos F.& Stocker T. F. . 2002 Revision of the global carbon budget due to changing air-sea oxygen fluxes. Global Biogeochem. Cycles 16, 1096 doi:10.1029/2001GB001746 (doi:10.1029/2001GB001746). Crossref, ISI, Google Scholar - 18
Bopp L., Le Quéré C., Heimann M., Manning A.& Monfray P. . 2002 Climate-induced oceanic oxygen fluxes: implications for the contemporary carbon budget. Global Biogeochem. Cycles 16, 1022 doi:10.1029/2001GB001445 (doi:10.1029/2001GB001445). Crossref, ISI, Google Scholar - 19
Stramma L., Johnson G. C., Sprintall J.& Mohrholz V. . 2008 Expanding oxygen-minimum zones in the tropical oceans. Science 320, 655-658doi:10.1126/science.1153847 (doi:10.1126/science.1153847). Crossref, PubMed, ISI, Google Scholar - 20
Gruber N., 2009 Oceanic sources, sinks, and transport of atmospheric CO2. Global Biogeochem. Cycles 23, GB1005 doi:10.1029/2008GB003349 (doi:10.1029/2008GB003349). Crossref, ISI, Google Scholar - 21
Manning A. C.& Keeling R. F. . 2006 Global oceanic and land biotic carbon sinks from the Scripps atmospheric oxygen flask sampling network. Tellus Ser. B 58, 95-116doi:10.1111/j.1600-0889.2006.00175.x (doi:10.1111/j.1600-0889.2006.00175.x). Crossref, Google Scholar - 22
Gilbert D., Rabalais N. N., Diaz R. J.& Zhang J. . 2010 Evidence for greater oxygen decline rates in the coastal ocean than in the open ocean. Biogeosciences 7, 2283-2296doi:10.5194/bg-7-2283-2010 (doi:10.5194/bg-7-2283-2010). Crossref, ISI, Google Scholar - 23
Rabalais N. N., Diaz R. J., Levin L. A., Turner R. E., Gilbert D.& Zhang J. . 2010 Dynamics and distribution of natural and human-caused hypoxia. Biogeosciences 7, 585-619doi:10.5194/bg-7-585-2010 (doi:10.5194/bg-7-585-2010). Crossref, ISI, Google Scholar - 24
Doney S. C. . 2010 The growing human footprint on coastal and open-ocean biogeochemistry. Science 328, 1210-1216doi:10.1126/science.1185198 (doi:10.1126/science.1185198). Crossref, ISI, Google Scholar - 25
Meehl G. A., 2007 Global climate projections. Climate change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Solomon S., Qin D., Manning M., Chen Z., Marquis M., Averyt K., Tignor M.& Miller H. Cambridge, UK Cambridge University Press. Google Scholar - 26
Frölicher T. L., Joos F., Plattner G.-K., Steinacher M.& Doney S. C. . 2009 Natural variability and anthropogenic trends in oceanic oxygen in a coupled carbon cycle-climate model ensemble. Global Biogeochem. Cycles 23, GB1003 doi:10.1029/2008GB003316 (doi:10.1029/2008GB003316). Crossref, ISI, Google Scholar - 27
Steinacher M., Joos F., Frölicher T. L., Plattner G.-K.& Doney S. C. . 2009 Imminent ocean acidification projected with the NCAR global coupled carbon cycle-climate model. Biogeosciences 6, 515-533doi:10.5194/bg-6-515-2009 (doi:10.5194/bg-6-515-2009). Crossref, ISI, Google Scholar - 28
Eppley R. W. . 1972 Temperature and phytoplankton growth in the sea. Fish. Bull. 70, 1063-1085. Google Scholar - 29
Laws E. A., Falkowski P., Carpenter E.& Ducklow H. . 2000 Temperature effects on export production in the open ocean. Global Biogeochem. Cycles 14, 1231-1246doi:10.1029/1999GB001229 (doi:10.1029/1999GB001229). Crossref, ISI, Google Scholar - 30
White P. A., Kalff J., Rasmussen J. B.& Gasol J. M. . 1991 The effect of temperature and algal biomass on bacterial production and specific growth rate in freshwater and marine habitats. Microb. Ecol. 21, 99-118doi:10.1007/BF02539147 (doi:10.1007/BF02539147). Crossref, PubMed, ISI, Google Scholar - 31
Kwon E. Y., Primeau F.& Sarmiento J. L. . 2009 The impact of remineralization depth on the air–sea carbon balance. Nat. Geosci. 2, 630-635doi:10.1038/NGEO612 (doi:10.1038/NGEO612). Crossref, ISI, Google Scholar - 32
Sarmiento J. L., 2004 Response of ocean ecosystems to climate warming. Global Biogeochem. Cycles 18, GB3003 doi:10.1029/2003GB002134 (doi:10.1029/2003GB002134). Crossref, ISI, Google Scholar - 33
Boyce D. G., Lewis M. R.& Worm B. . 2010 Global phytoplankton decline over the past century. Nature 466, 591-596doi:10.1038/nature09268 (doi:10.1038/nature09268). Crossref, PubMed, ISI, Google Scholar - 34
Behrenfeld M. J., 2006 Climate-driven trends in contemporary ocean productivity. Nature 444, 752-755doi:10.1038/nature05317 (doi:10.1038/nature05317). Crossref, PubMed, ISI, Google Scholar - 35
Friedlingstein P., 2006 Climate-carbon cycle feedback analysis: results from the C4MIP model intercomparison. J. Clim. 19, 3337-3353doi:10.1175/JCLI3800.1 (doi:10.1175/JCLI3800.1). Crossref, ISI, Google Scholar - 36
Plattner G.-K., 2008 Long-term climate commitments projected with climate-carbon cycle models. J. Clim. 21, 2721-2751doi:10.1175/2007JCLI1905.1 (doi:10.1175/2007JCLI1905.1). Crossref, ISI, Google Scholar - 37
Gloor M., Gruber N.& Sarmiento J. . 2010 What can be learned about carbon cycle climate feedbacks from the CO2 airborne fraction? Atmos. Chem. Phys. 10, 7739-7751doi:10.5194/acp-10-7739-2010 (doi:10.5194/acp-10-7739-2010). Crossref, ISI, Google Scholar - 38
McNeil B. I.& MatearR J. . 2008 Southern Ocean acidification: a tipping point at 450 ppm atmospheric CO2. Proc. Natl Acad. Sci. USA 105, 18 860-18 864doi:10.1073/pnas.0806318105 (doi:10.1073/pnas.0806318105). Google Scholar - 39
Feely R. A., Sabine C. L., Lee K., Berelson W., Kleypas J., Fabry V. J.& Millero F. J. . 2004 Impact of anthropogenic CO2 on the CaCO3 system in the oceans. Science 305, 362-366doi:10.1126/science.1097329 (doi:10.1126/science.1097329). Crossref, PubMed, ISI, Google Scholar - 40
Doney S. C., Fabry V. J., Feely R. A.& Kleypas J. A. . 2009 Ocean acidification: the other CO2 problem. Annu. Rev. Mar. Sci. 1, 169-192doi:10.1146/annurev.marine.010908.163834 (doi:10.1146/annurev.marine.010908.163834). Crossref, PubMed, ISI, Google Scholar - 41
Hutchins D. A., Mulholland M. R.& Fu F. . 2009 Nutrient cycles and marine microbes in a CO2 enriched ocean. Oceanography 22, 128-145. Crossref, ISI, Google Scholar - 42
Sarmiento J. L., Le Quéré C.& Pacala S. W. . 1995 Limiting future atmospheric carbon dioxide. Global Biogeochem. Cycles 9, 121-137doi:10.1029/94GB01779 (doi:10.1029/94GB01779). Crossref, ISI, Google Scholar - 43
Gruber N., Friedlingstein P., Field C. B., Valentini R., Heimann M., Richey J. E., Romero-Lankau P., Schulze E.-D.& Chen C. -T A. . 2004 The vulnerability of the carbon cycle in the 21st century: an assessment of carbon–climate–human interactions. The global carbon cycle: integrating humans, climate, and the natural world, Field C. B.& Raupach M. R. Washington, DC Island Press 45-76. Google Scholar - 44
Riebesell U., 2007 Enhanced biological carbon consumption in a high CO2 ocean. Nature 450, 545-548doi:10.1038/nature06267 (doi:10.1038/nature06267). Crossref, PubMed, ISI, Google Scholar - 45
Oschlies A., Schulz K. G., Riebesell U.& Schmittner A. . 2008 Simulated 21st century’s increase in oceanic suboxia by CO2-enhanced biotic carbon export. Global Biogeochem. Cycles 22, GB4008 doi:10.1029/2007GB003147 (doi:10.1029/2007GB003147). Crossref, ISI, Google Scholar - 46
Hofmann M.& Schellnhuber H.-J. . 2009 Oceanic acidification affects marine carbon pump and triggers extended marine oxygen holes. Proc. Natl Acad. Sci. USA 106, 3017–3022doi:10.1073/pnas.0813384106 (doi:10.1073/pnas.0813384106). Google Scholar - 47
Gehlen M., Gruber N., Gangsto R., Bopp L.& Oschlies A. . 2011 Biogeochemical consequences of ocean acidification and feedbacks to the earth sysatem. Ocean acidification, Gattuso J.-P.& Hansson L. Cambridge, UK Cambridge University Press ch. 12. Google Scholar - 48
Matear R. J., Hirst A. C.& McNeil B. I. . 2000 Changes in dissolved oxygen in the Southern Ocean with climate change. Geochem. Geophys. Geosyst. 1, 1050 doi:10.1029/2000GC000086 (doi:10.1029/2000GC000086). Crossref, ISI, Google Scholar - 49
Schmittner A., Oschlies A., Matthews H. D.& Galbaith E. D. . 2008 Future changes in climate, ocean circulation, ecosystems, and biogeochemical cycling simulated for a business-as-usual CO2 emission scenario until year 4000 AD. Global Biogeochem. Cycles 22, GB1013 doi:10.1029/2007GB002953 (doi:10.1029/2007GB002953). Crossref, ISI, Google Scholar - 50
Jin X.& Gruber N. . 2003 Offsetting the radiative benefit of ocean iron fertilization by enhancing N2O emissions. Geophys. Res. Lett. 30, 2249 doi:10.1029/2003GL018458 (doi:10.1029/2003GL018458). Crossref, ISI, Google Scholar - 51
Vaquer-Sunyer R.& Duarte C. M. . 2008 Thresholds of hypoxia for marine biodiversity. Proc. Natl Acad. Sci. USA 105, 15 452-15 457doi:10.1073/pnas.0803833105 (doi:10.1073/pnas.0803833105). Google Scholar - 52
Suntharalingam P., Sarmiento J. L.& Toggweiler J. R. . 2000 Global significance of nitrous-oxide production and transport from oceanic low-oxygen zones: a modeling study. Global Biogeochem. Cycles 14, 1353-1370doi:10.1029/1999GB900100 (doi:10.1029/1999GB900100). Crossref, ISI, Google Scholar - 53
Nevison C. D., Butler J.& Elkins J. . 2003 Global distribution of N2O and the δN2O/AOU yield in the subsurface ocean. Global Biogeochem. Cycles 17, 1119 doi:10.1029/2003GB002068 (doi:10.1029/2003GB002068). Crossref, ISI, Google Scholar - 54
Gruber N. . 2008 The marine nitrogen cycle: overview and challenges. Nitrogen in the marine environment, Capone D. G., Bronk D. A., Mulholland M. R.& Carpenter E. San Diego, CA Academic Press ch. 1, 2nd edn. Google Scholar - 55
Brewer P. G.& Peltzer E. T. . 2009 Limits to marine life. Science 324, 347-348doi:10.1126/science.1170756 (doi:10.1126/science.1170756). Crossref, PubMed, ISI, Google Scholar - 56
Portner H.-O. . 2010 Oxygen- and capacity-limitation of thermal tolerance: a matrix for integrating climate-related stressor effects in marine ecosystems. J. Exp. Biol. 213, 881-893doi:10.1242/jeb.0375523 (doi:10.1242/jeb.0375523). Crossref, PubMed, ISI, Google Scholar - 57
Hutchins D. A., Fu F. X., Zhang Y., Warner M. E., Feng Y., Portune K., Bernhardt P. W.& Mulholland M. R. . 2007 CO2 control of Trichodesmium N2 fixation, photosynthesis, growth rates and elemental ratios: implications for past, present and future ocean. Limnol. Oceanogr. 52, 1293-1304doi:10.4319/lo.2007.52.4.1293 (doi:10.4319/lo.2007.52.4.1293). Crossref, ISI, Google Scholar - 58
Metzger R., Sartoris F., Langebuch M.& Pörtner H. O. . 2007 Influence of elevated CO2 concentrations on thermal tolerance of the edible crab, Cancer Pagurus. J. Thermal Biol. 32, 144-151doi:10.1016/j.jtherbio.2007.01.010 (doi:10.1016/j.jtherbio.2007.01.010). Crossref, ISI, Google Scholar - 59
Fréon P., Barrange M.& Aristegui J. . 2009 Eastern boundary upwelling ecosystems: integrative and comparative approaches. Prog. Oceanogr. 83, 1-14doi:10.1016/j.pocean.2009.08.001 (doi:10.1016/j.pocean.2009.08.001). Crossref, ISI, Google Scholar - 60
Bakun A. . 1990 Coastal ocean upwelling. Science 247, 198-201doi:10.1126/science.247.4939.198 (doi:10.1126/science.247.4939.198). Crossref, PubMed, ISI, Google Scholar - 61
Diffenbaugh N. S. . 2005 Response of large-scale eastern boundary current forcing in the 21st century. Geophys. Res. Lett. 32, L19718 doi:10.1029/2005GL023905 (doi:10.1029/2005GL023905). Crossref, ISI, Google Scholar - 62
Feely R. A., Sabine C. L., Hernandez-Ayon M., Ianson D.& Hales B. . 2008 Evidence for upwelling of corrosive ‘acidified’ water onto the continental shelf. Science 320, 1490-1492doi:10.1126/science.1155676 (doi:10.1126/science.1155676). Crossref, PubMed, ISI, Google Scholar - 63
Bograd S. J., Castro C. G., Lorenzo E. D., Palacios D. M., Bailey H., Gilly W.& Chavez F. P. . 2008 Oxygen declines and the shoaling of the hypoxic boundary in the California Current. Geophys. Res. Lett. 35, L12607 doi:10.1029/2008GL034185 (doi:10.1029/2008GL034185). Crossref, ISI, Google Scholar - 64
Chan F., Barth J. A., Lubchenco J., Kirincich A., Weeks H., Peterson W. T.& Menge B. A. . 2008 Emergence of anoxia in the California Current large marine ecosystem. Science 319, 920 doi:10.1126/science.1149016 (doi:10.1126/science.1149016). Crossref, PubMed, ISI, Google Scholar - 65
Hauri C., Gruber N., Plattner G.-K., Alin S., Feely R. A., Hales B.& Wheeler P. . 2009 Ocean acidification in the California Current System. Oceanography 22, 60-71. Crossref, ISI, Google Scholar - 66
Solomon S., Plattner G.-K., Knutti R.& Friedlingstein P. . 2009 Irreversible climate change due to carbon dioxide emissions. Proc. Natl Acad. Sci. USA 106, 1704–1709doi:10.1073/pnas.0812721106 (doi:10.1073/pnas.0812721106). Google Scholar - 67
Archer D., 2009 Atmospheric lifetime of fossil fuel carbon dioxide. Annu. Rev. Earth Planet. Sci. 37, 117-134doi:10.1146/annurev.earth.031208.100206 (doi:10.1146/annurev.earth.031208.100206). Crossref, ISI, Google Scholar - 68
Meehl G. A., Washington W. M., Collins W. D., Arblaster J. M., Hu A., Buja L. E., Strand W. G.& Teng H. . 2005 How much more global warming and sea level rise? Science 307, 1769-1772doi:10.1126/science.1106663 (doi:10.1126/science.1106663). Crossref, PubMed, ISI, Google Scholar