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Emerging impact of Greenland meltwater on deepwater formation in the North Atlantic Ocean

Nature Geoscience volume 9, pages 523527 (2016) | Download Citation

Abstract

The Greenland ice sheet has experienced increasing mass loss since the 1990s1,2. The enhanced freshwater flux due to both surface melt and outlet glacier discharge is assuming an increasingly important role in the changing freshwater budget of the subarctic Atlantic3. The sustained and increasing freshwater fluxes from Greenland to the surface ocean could lead to a suppression of deep winter convection in the Labrador Sea, with potential ramifications for the strength of the Atlantic meridional overturning circulation4,5,6. Here we assess the impact of the increases in the freshwater fluxes, reconstructed with full spatial resolution3, using a global ocean circulation model with a grid spacing fine enough to capture the small-scale, eddying transport processes in the subpolar North Atlantic. Our simulations suggest that the invasion of meltwater from the West Greenland shelf has initiated a gradual freshening trend at the surface of the Labrador Sea. Although the freshening is still smaller than the variability associated with the episodic ‘great salinity anomalies’, the accumulation of meltwater may become large enough to progressively dampen the deep winter convection in the coming years. We conclude that the freshwater anomaly has not yet had a significant impact on the Atlantic meridional overturning circulation.

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References

  1. 1.

    , & Satellite gravity measurements confirm accelerated melting of Greenland ice sheet. Science 313, 1958–1960 (2006).

  2. 2.

    et al. Timing and origin of recent regional ice-mass loss in Greenland. Earth Planet. Sci. Lett. 333–334, 293–303 (2012).

  3. 3.

    , , , & Recent large increases in freshwater fluxes from Greenland into the North Atlantic. Geophys. Res. Lett. 39, L19501 (2012).

  4. 4.

    et al. Investigating the causes of the response of the thermohaline circulation to past and future climate changes. J. Clim. 19, 1365–1387 (2006).

  5. 5.

    et al. Decadal fingerprints of freshwater discharge around Greenland in a multi-model ensemble. Clim. Dynam. 41, 695–720 (2013).

  6. 6.

    et al. Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation. Nature Clim. Change 5, 475–480 (2015).

  7. 7.

    , , & A simple model of seasonal open ocean convection. Part II: Labrador Sea stability and stochastic forcing. Ocean Dynam. 52, 36–49 (2001).

  8. 8.

    Oceanographic conditions at Ocean Weather Ship Bravo, 1964–1974. Atmos.-Ocean 18, 227–238 (1980).

  9. 9.

    , & Mechanisms behind the temporary shutdown of deep convection in the Labrador Sea: lessons from the Great Salinity Anomaly years 1968–71. J. Clim. 25, 6743–6755 (2012).

  10. 10.

    et al. Oceanic transport of surface meltwater from the southern Greenland ice sheet. Nature Geosci. (2016).

  11. 11.

    , & Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2. Cryosphere 8, 1539–1559 (2014).

  12. 12.

    & Dilution of the northern North Atlantic Ocean in recent decades. Science 308, 1772–1774 (2005).

  13. 13.

    et al. Changes in freshwater content in the North Atlantic Ocean 1955–2006. Geophys. Res. Lett. 34, L16603 (2007).

  14. 14.

    Eddies in the Labrador Sea as observed by profiling RAFOS floats and remote sensing. J. Phys. Oceanogr. 32, 411–427 (2002).

  15. 15.

    et al. Observations of the Labrador Sea eddy field. Prog. Oceanogr. 59, 75–176 (2003).

  16. 16.

    , & Boundary current eddies and their role in the restratification of the Labrador Sea. J. Phys. Oceanogr. 34, 1967–1983 (2004).

  17. 17.

    & Effect of freshwater from the West Greenland Current on the winter deep convection in the Labrador Sea. Ocean Model. 75, 51–64 (2014).

  18. 18.

    , , , & Response of the Atlantic Ocean circulation to Greenland ice sheet melting in a strongly-eddying ocean model. Geophys. Res. Lett. 39, L09606 (2012).

  19. 19.

    et al. Response of a strongly eddying global ocean to North Atlantic freshwater perturbations. J. Phys. Oceanogr. 44, 464–481 (2014).

  20. 20.

    et al. Circulation and transports in the Newfoundland Basin, western subpolar North Atlantic. J. Geophys. Res. Oceans 119, 7772–7793 (2014).

  21. 21.

    & The global climatology of an interannually varying air–sea flux data set. Clim. Dynam. 33, 341–364 (2009).

  22. 22.

    et al. Coordinated Ocean-ice Reference Experiments (COREs). Ocean Model. 26, 1–46 (2009).

  23. 23.

    et al. Short-term impacts of enhanced Greenland freshwater fluxes in an eddy-permitting ocean model. Ocean Sci. 6, 749–760.

  24. 24.

    , & Potential positive feedback between Greenland ice sheet melt and Baffin Bay heat content on the west Greenland shelf. Geophys. Res. Lett. 42, 4922–4930 (2015).

  25. 25.

    & Quasi-decadal salinity fluctuations in the Labrador Sea. J. Phys. Oceanogr. 32, 687–701 (2002).

  26. 26.

    , , & The “Great Salinity Anomaly” in the northern North Atlantic 1968–1982. Prog. Oceanogr. 20, 103–151 (1988).

  27. 27.

    , , & “Great salinity anomalies” in the North Atlantic. Prog. Oceanogr. 41, 1–68 (1998).

  28. 28.

    Fram Strait ice fluxes and atmospheric circulation: 1950–2000. J. Clim. 14, 3508–3516 (2001).

  29. 29.

    et al. in Arctic-Subarctic Ocean Fluxes (eds Dickson, R. R., Meincke, J. & Rhines, P.) 653–701 (Springer, 2008).

  30. 30.

    , & Evaluation of the ECMWF ocean reanalysis system ORAS4. Q. J. R. Meteorol. Soc. 139, 1132–1161 (2013).

  31. 31.

    and the NEMO team. NEMO Ocean Engine (Institut Pierre-Simon Laplace No. 27, 2008).

  32. 32.

    et al. DRAKKAR: Developing high resolution ocean components for European Earth system models. CLIVAR Exchanges 19, 18–21 (2014).

  33. 33.

    & Sensitivity of a global sea ice model to the treatment of ice thermodynamics and dynamics. J. Geophys. Res. 102, 12609–12646 (1997).

  34. 34.

    & Variability of the tropical Atlantic Ocean simulated by a general circulation model with two different mixed-layer physics. J. Phys. Oceanogr. 23, 1363–1388 (1993).

  35. 35.

    et al. Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution. Ocean Dynam. 56, 543–567 (2006).

  36. 36.

    , & AGRIF: Adaptive grid refinement in FORTRAN. Comp. Geosci. 34, 8–13 (2008).

  37. 37.

    et al. An improved mass budget for the Greenland ice sheet. Geophys. Res. Lett. 41, 866–872 (2014).

  38. 38.

    et al. Impact of fjord dynamics and glacial runoff on the circulation near Helheim Glacier. Nature Geosci. 4, 322–327 (2011).

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Acknowledgements

The model computations were performed at the North-German Supercomputing Alliance (HLRN). The study was supported by the cooperative programme ‘RACE—Regional Atlantic Circulation and Global Change’ (BMBF grant 03F0651B), and the Cluster of Excellence ‘The Future Ocean’ funded by the DFG. The authors wish to thank the DRAKKAR group for their continuous support in the model development.

Author information

Affiliations

  1. GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany

    • Claus W. Böning
    • , Erik Behrens
    • , Arne Biastoch
    •  & Klaus Getzlaff
  2. National Institute for Water and Atmospheric Research, 301 Evans Parade, Hataitai, Wellington 6021, New Zealand

    • Erik Behrens
  3. School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK

    • Jonathan L. Bamber

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Contributions

All authors conceived the experiments. E.B. implemented the model and performed the experiments. E.B., C.W.B., K.G. and A.B. analysed the results. C.W.B. wrote the paper with contributions by all co-authors.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Claus W. Böning.

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DOI

https://doi.org/10.1038/ngeo2740