Letter | Published:

Rapid coastal deoxygenation due to ocean circulation shift in the northwest Atlantic

Nature Climate Changevolume 8pages868872 (2018) | Download Citation


Global observations show that the ocean lost approximately 2% of its oxygen inventory over the past five decades1,2,3, with important implications for marine ecosystems4,5. The rate of change varies regionally, with northwest Atlantic coastal waters showing a long-term drop6,7 that vastly outpaces the global and North Atlantic basin mean deoxygenation rates5,8. However, past work has been unable to differentiate the role of large-scale climate forcing from that of local processes. Here, we use hydrographic evidence to show that a Labrador Current retreat is playing a key role in the deoxygenation on the northwest Atlantic shelf. A high-resolution global coupled climate–biogeochemistry model9 reproduces the observed decline of saturation oxygen concentrations in the region, driven by a retreat of the equatorward-flowing Labrador Current and an associated shift towards more oxygen-poor subtropical waters on the shelf. The dynamical changes underlying the shift in shelf water properties are correlated with a slowdown in the simulated Atlantic Meridional Overturning Circulation (AMOC)10. Our results provide strong evidence that a major, centennial-scale change of the Labrador Current is underway, and highlight the potential for ocean dynamics to impact coastal deoxygenation over the coming century.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Helm, K. P., Bindoff, N. L., & Church, J. A. Observed decreases in oxygen content of the global ocean.Geophys. Res. Lett. 38, L23602 (2011).

  2. 2.

    Schmidtko, S., Stramma, L. & Visbeck, M. Decline in global oceanic oxygen content during the past five decades. Nature 542, 335–339 (2017).

  3. 3.

    Ito, T., Minobe, S., Long, M. C. & Deutsch, C. Upper ocean O2 trends: 1958–2015. Geophys. Res. Lett. 44, 4214–4223 (2017).

  4. 4.

    Breitburg, D. et al. Declining oxygen in the global ocean and coastal waters.Science 359, eaam7240 (2018).

  5. 5.

    Levin, L. A. Manifestation, drivers, and emergence of open ocean deoxygenation. Ann. Rev. Mar. Sci. 10, 229–260 (2018).

  6. 6.

    Petrie, B. & Yeats, P. Annual and interannual variability of nutrients and their estimated fluxes in the Scotian Shelf—Gulf of Maine region. Can. J. Fish. Aquat. Sci. 57, 2536–2546 (2000).

  7. 7.

    Gilbert, D., Sundby, B., Gobeil, C., Mucci, A. & Tremblay, G.-H. A seventy-two-year record of diminishing deep-water oxygen in the St. Lawrence estuary: the northwest Atlantic connection. Limnol. Oceanogr. 50, 1654–1666 (2005).

  8. 8.

    Gilbert, D., Rabalais, N. N., Díaz, R. J. & Zhang, J. Evidence for greater oxygen decline rates in the coastal ocean than in the open ocean. Biogeosciences 7, 2283–2296 (2010).

  9. 9.

    Dufour, C. O. et al. Role of mesoscale eddies in cross-frontal transport of heat and biogeochemical tracers in the Southern Ocean. J. Phys. Oceanogr. 45, 3057–3081 (2015).

  10. 10.

    Caesar, L., Rahmstorf, S., Robinson, A., Feulner, G. & Saba, V. Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature 556, 191–196 (2018).

  11. 11.

    Keeling, R. F., Körtzinger, A. & Gruber, N. Ocean deoxygenation in a warming world. Ann. Rev. Mar. Sci. 2, 199–229 (2010).

  12. 12.

    Long, M. C., Deutsch, C. & Ito, T. Finding forced trends in oceanic oxygen. Glob. Biogeochem. Cycles 30, 381–397 (2016).

  13. 13.

    Johnson, G. C. & Gruber, N. Decadal water mass variations along 20° W in the Northeastern Atlantic Ocean. Prog. Oceanogr. 73, 277–295 (2007).

  14. 14.

    Frölicher, T. L., Joos, F., Plattner, G.-K., Steinacher, M. & Doney, S. C. Natural variability and anthropogenic trends in oceanic oxygen in a coupled carbon cycle-climate model ensemble. Glob. Biogeochem. Cycles 23, GB1003 (2009).

  15. 15.

    Stendardo, I. & Gruber, N. Oxygen trends over five decades in the North Atlantic.J. Geophys. Res. Oceans 117, C11004 (2012).

  16. 16.

    Brennan, C. E., Blanchard, H. & Fennel, K. Putting temperature and oxygen thresholds of marine animals in context of environmental change: a regional perspective for the Scotian Shelf and Gulf of St. Lawrence. PLoS ONE 11, 1–27 (2016).

  17. 17.

    Thibodeau, B., de Vernal, A., Hillaire-Marcel, C. & Mucci, A. Twentieth century warming in deep waters of the Gulf of St. Lawrence: A unique feature of the last millennium. Geophys. Res. Lett. 37, L17604 (2010).

  18. 18.

    Genovesi, L. et al. Recent changes in bottom water oxygenation and temperature in the Gulf of St. Lawrence: micropaleontological and geochemical evidence. Limnol. Oceanogr. 56, 1319–1329 (2011).

  19. 19.

    Keigwin, L., Sachs, J. & Rosenthal, Y. A 1600-year history of the Labrador Current off Nova Scotia. Clim. Dynam. 12, 53–62 (2003).

  20. 20.

    Sherwood, O. A., Lehmann, M. F., Schubert, C. J., Scott, D. B. & McCarthy, M. D. Nutrient regime shift in the western North Atlantic indicated by compound-specific δ15N of deep-sea gorgonian corals. Proc. Natl Acad. Sci. USA 108, 1011–1015 (2011).

  21. 21.

    Thornalley, D. J. R. et al. Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years. Nature 556, 227–230 (2018).

  22. 22.

    Loder, J. W., van der Baaren, A. & Yashayaev, I. Climate comparisons and change projections for the Northwest Atlantic from six CMIP5 models. Atmos. Ocean 53, 529–555 (2015).

  23. 23.

    Saba, V. S. et al. Enhanced warming of the Northwest Atlantic Ocean under climate change. J. Geophys. Res. Oceans 121, 118–132 (2016).

  24. 24.

    Lavoie, D., Lambert, N. & Gilbert, D. Projections of future trends in biogeochemical conditions in the northwest Atlantic using CMIP5 Earth system models. Atmos. Ocean https://doi.org/10.1080/07055900.2017.1401973 (2017).

  25. 25.

    Joyce, T. M. & Zhang, R. On the path of the Gulf Stream and the Atlantic Meridional Overturning Circulation. J. Clim. 23, 3146–3154 (2010).

  26. 26.

    Buckley, M. W. & Marshall, J. Observations, inferences, and mechanisms of the Atlantic Meridional Overturning Circulation: a review. Rev. Geophys. 54, 5–63 (2016).

  27. 27.

    Petrie, B. & Drinkwater, K. Temperature and salinity variability on the Scotian Shelf and in the Gulf of Maine 1945–1990. J. Geophys. Res. Oceans 98, 20079–20089 (1993).

  28. 28.

    Peterson, I., Greenan, B., Gilbert, D. & Hebert, D. Variability and wind forcing of ocean temperature and thermal fronts in the Slope Water region of the Northwest Atlantic. J. Geophys. Res. Oceans 122, 7325–7343 (2017).

  29. 29.

    Bianucci, L., Fennel, K., Chabot, D., Shackell, N. & Lavoie, D. Ocean biogeochemical models as management tools: a case study for Atlantic wolffish and declining oxygen. ICES J. Mar. Sci. 73, 263–274 (2016).

  30. 30.

    Tagklis, F., Bracco, A. & Ito, T. Physically driven patchy O2 changes in the North Atlantic Ocean simulated by the CMIP5 Earth system models. Glob. Biogeochem. Cycles 31, 1218–1235 (2017).

  31. 31.

    Gatien, M. G. A study in the slope water region south of Halifax. J. Fish Res. Board Can. 33, 2213–2217 (1976).

  32. 32.

    Bisagni, J. J., Gangopadhyay, A. & Sanchez-Franks, A. Secular change and inter-annual variability of the Gulf Stream position, 1993–2013, 70°–55° W. Deep Sea Res. I 125, 1–10 (2017).

  33. 33.

    Warren, B. A. Nansen-bottle stations at the Woods Hole Oceanographic Institution. Deep Sea Res. I 55, 379–395 (2008).

  34. 34.

    Millero, F. J., Chen, C.-T., Bradshaw, A. & Schleicher, K. A new high pressure equation of state for seawater. Deep Sea Res. A 27, 255–264 (1980).

  35. 35.

    Galbraith, E. D. et al. Complex functionality with minimal computation: promise and pitfalls of reduced-tracer ocean biogeochemistry models. J. Adv. Model. Earth Syst. 7, 2012–2028 (2015).

Download references


The authors thank A. Cogswell and R. Pettipas from Fisheries and Oceans Canada for providing hydrographic data in the central Scotian Shelf and C. E. Brennan for providing the data for the oxygen time series in the central Scotian Shelf. The authors also acknowledge many scientists at NOAA GFDL that configured and ran the climate model, without whose efforts this work would not have been possible. This project has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant no. 682602). E.D.G. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through the Mara de Maeztu Programme for Centres/Units of Excellence (MDM-2015-0552). The Canadian Foundation for Innovation provided the computing resources for model analysis. D.B. acknowledges support from NOAA grant NA15NOS4780186.

Author information


  1. Joint Institute for the Study of the Atmosphere and the Ocean, Seattle, WA, USA

    • Mariona Claret
  2. University of Washington, Seattle, WA, USA

    • Mariona Claret
  3. Department of Earth and Planetary Sciences, McGill University, Montréal, Quebec, Canada

    • Mariona Claret
    •  & Eric D. Galbraith
  4. Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain

    • Eric D. Galbraith
  5. Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain

    • Eric D. Galbraith
  6. Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA

    • Jaime B. Palter
  7. Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA

    • Daniele Bianchi
  8. Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada

    • Katja Fennel
  9. Maurice Lamontagne Institute, Fisheries and Oceans Canada, Mont-Joli, Quebec, Canada

    • Denis Gilbert
  10. NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA

    • John P. Dunne


  1. Search for Mariona Claret in:

  2. Search for Eric D. Galbraith in:

  3. Search for Jaime B. Palter in:

  4. Search for Daniele Bianchi in:

  5. Search for Katja Fennel in:

  6. Search for Denis Gilbert in:

  7. Search for John P. Dunne in:


E.D.G., J.B.P. and D.B. conceived the study. M.C., D.G. and K.F. assembled and analysed the observational data. M.C. and D.B. performed the model output analyses. J.P.D. and E.D.G. participated in the design of the CM2.6-miniBLING experiments. M.C., E.D.G., J.B.P. and D.B. wrote the first draft of the manuscript. All the authors discussed the results and provided input to the manuscript.

Competing interests

The authors declare no competing Interests.

Corresponding author

Correspondence to Mariona Claret.

Supplementary information

  1. Supplementary Information Description: Supplementary figures 1–9, Supplementary Notes, Supplementary References, Supplementary Tables 1–3

    Supplementary figures 1–9, Supplementary Notes, Supplementary References, Supplementary Tables 1–3

  2. Supplementary Video 1

    Time evolution of simulated O2 in the northwest Atlantic on isopycnal σθ = 27.25 kg m−3 over the last twenty model years (from 181 to 200) for preindustrial control (LEFT) and warming (1% annual pCO2 increase until doubled, RIGHT) scenarios. Climate model horizontal resolution is 1/10° and the time period between movie frames is five days. The movie shows that the oxygen supply to slope waters (white shading in Fig. 1) and the Laurentian Channel decreases significantly under warming due to a reduction in transport of ventilated Labrador Current waters west of the Tail of the Grand Banks. Isopycnal outcrop is shown in white

About this article

Publication history




Issue Date