Multiple drivers of the North Atlantic warming hole

Abstract

Despite global warming, a region in the North Atlantic ocean has been observed to cool, a phenomenon known as the warming hole. Its emergence has been linked to a slowdown of the Atlantic meridional overturning circulation, which leads to a reduced ocean heat transport into the warming hole region. Here we show that, in addition to the reduced low-latitude heat import, increased ocean heat transport out of the region into higher latitudes and a shortwave cloud feedback dominate the formation and temporal evolution of the warming hole under greenhouse gas forcing. In climate model simulations of the historical period, the low-latitude Atlantic meridional overturning circulation decline does not emerge from natural variability, whereas the accelerating heat transport to higher latitudes is clearly attributable to anthropogenic forcing. Both the overturning and the gyre circulation contribute to the increased high-latitude ocean heat transport, and therefore are critical to understand the past and future evolutions of the warming hole.

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Fig. 1: Linear surface temperature trends in the North Atlantic.
Fig. 2: WHI for all the simulations forced by the 1pctCO2 increase per year scenario.
Fig. 3: Relationship between AMOC strength and the WHI for various simulations and observations.
Fig. 4: North Atlantic OHT changes in the Grand Ensemble.
Fig. 5: Schematic illustration of the drivers of the WH.
Fig. 6: Relationship of the total advective heat transport at low and high latitudes in the Grand Ensemble.

Data availability

HadCRUT4 data were provided by the UK Met Office Hadley Centre (http://www.met-office.gov.uk/hadobs/hadcrut4/), as well as HadISST data (https://www.metoffice.gov.uk/hadobs/hadisst/). Data from the RAPID-WATCH MOC monitoring project are freely available from www.rapid.ac.uk/rapidmoc funded by the Natural Environment Research Council. The Grand Ensemble is publicly available at ESGF (https://esgf-data.dkrz.de/projects/esgf-dkrz/). The special simulations are available on request from the corresponding author.

Code availability

An archive with the bash, python and NCL scripts used to conduct the calculations that underlie this study and reproduce the figures is archived by the Max Planck Institute for Meteorology and can be accessed from the public repository of the Max Planck Society, https://pure.mpg.de/pubman/faces/ViewItemOverviewPage.jsp?itemId=item_3213979.

References

  1. 1.

    Seager, R. et al. Is the gulf stream responsible for Europe’s mild winters? Q. J. R. Meteorol. Soc. 128, 2563–2586 (2002).

    Article  Google Scholar 

  2. 2.

    Kaspi, Y. & Schneider, T. Winter cold of eastern continental boundaries induced by warm ocean waters. Nature 471, 621–624 (2011).

    CAS  Article  Google Scholar 

  3. 3.

    Stocker, T. F. & Wright, D. G. Rapid transitions of the ocean’s deep circulation induced by changes in surface water fluxes. Nature 351, 729–732 (1991).

    Article  Google Scholar 

  4. 4.

    Rahmstorf, S. Bifurcations of the Atlantic thermohaline circulation in response to changes in the hydrological cycle. Nature 378, 145–149 (1995).

    CAS  Article  Google Scholar 

  5. 5.

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

    Article  Google Scholar 

  6. 6.

    Sévellec, F., Fedorov, A. V. & Liu, W. Arctic sea-ice decline weakens the Atlantic meridional overturning circulation. Nat. Clim. Change 7, 604–610 (2017).

    Article  Google Scholar 

  7. 7.

    Drijfhout, S., Van Oldenborgh, G. J. & Cimatoribus, A. Is a decline of AMOC causing the warming hole above the North Atlantic in observed and modeled warming patterns? J. Clim. 25, 8373–8379 (2012).

    Article  Google Scholar 

  8. 8.

    Menary, M. B. & Wood, R. A. An anatomy of the projected North Atlantic warming hole in CMIP5 models. Clim. Dynam. 50, 3063–3080 (2018).

    Article  Google Scholar 

  9. 9.

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

    CAS  Article  Google Scholar 

  10. 10.

    Gervais, M., Shaman, J. & Kushnir, Y. Mechanisms governing the development of the North Atlantic warming hole in the CESM-LE future climate simulations. J. Clim. 31, 5927–5946 (2018).

    Article  Google Scholar 

  11. 11.

    Laurian, A., Drijfhout, S., Hazeleger, W. & van den Hurk, B. Response of the Western European climate to a collapse of the thermohaline circulation. Clim. Dynam. 34, 689–697 (2010).

    Article  Google Scholar 

  12. 12.

    Haarsma, R. J., Selten, F. M. & Drijfhout, S. S. Decelerating Atlantic meridional overturning circulation main cause of future West European summer atmospheric circulation changes. Environ. Res. Lett. 10, 094007 (2015).

    Article  Google Scholar 

  13. 13.

    Gervais, M., Shaman, J. & Kushnir, Y. Impacts of the North Atlantic warming hole in future climate projections: mean atmospheric circulation and the North Atlantic jet. J. Clim. 32, 2673–2689 (2019).

    Article  Google Scholar 

  14. 14.

    Smeed, D. et al. Observed decline of the Atlantic meridional overturning circulation 2004–2012. Ocean Sci. 10, 29–38 (2014).

    Article  Google Scholar 

  15. 15.

    Jackson, L. C., Peterson, K. A., Roberts, C. D. & Wood, R. A. Recent slowing of Atlantic overturning circulation as a recovery from earlier strengthening. Nat. Geosci. 9, 518–522 (2016).

    CAS  Article  Google Scholar 

  16. 16.

    Maher, N. et al. The Max Planck Institute Grand Ensemble—enabling the exploration of climate system variability. J. Adv. Model. Earth Syst. 11, 2050–2069 (2019).

    Article  Google Scholar 

  17. 17.

    Booth, B. B., Dunstone, N. J., Halloran, P. R., Andrews, T. & Bellouin, N. Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability. Nature 484, 228–232 (2012).

    CAS  Article  Google Scholar 

  18. 18.

    Sutton, R. T., Dong, B. & Gregory, J. M. Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations. Geophys. Res. Lett. 34, L02701 (2007).

    Article  Google Scholar 

  19. 19.

    Ceppi, P., McCoy, D. T. & Hartmann, D. L. Observational evidence for a negative shortwave cloud feedback in middle to high latitudes. Geophys. Res. Lett. 43, 1331–1339 (2016).

    Article  Google Scholar 

  20. 20.

    Trossman, D., Palter, J., Merlis, T., Huang, Y. & Xia, Y. Large-scale ocean circulation–cloud interactions reduce the pace of transient climate change. Geophys. Res. Lett. 43, 3935–3943 (2016).

    Article  Google Scholar 

  21. 21.

    Oldenburg, D., Armour, K. C., Thompson, L. & Bitz, C. M. Distinct mechanisms of ocean heat transport into the Arctic under internal variability and climate change. Geophys. Res. Lett. 45, 7692–7700 (2018).

    Article  Google Scholar 

  22. 22.

    Jungclaus, J. et al. Characteristics of the ocean simulations in the Max Planck Institute Ocean Model (MPIOM) the ocean component of the MPI-Earth system model. J. Adv. Model. Earth Syst. 5, 422–446 (2013).

    Article  Google Scholar 

  23. 23.

    Senior, C. A. & Mitchell, J. F. The time-dependence of climate sensitivity. Geophys. Res. Lett. 27, 2685–2688 (2000).

    CAS  Article  Google Scholar 

  24. 24.

    Armour, K. C., Bitz, C. M. & Roe, G. H. Time-varying climate sensitivity from regional feedbacks. J. Clim. 26, 4518–4534 (2013).

    Article  Google Scholar 

  25. 25.

    Mauritsen, T. et al. Developments in the MPI-M Earth System Model version 1.2 (MPI-ESM1. 2) and its response to increasing CO2. J. Adv. Model. Earth Syst. 11, 998–1038 (2019).

    Article  Google Scholar 

  26. 26.

    Clement, A. et al. The Atlantic multidecadal oscillation without a role for ocean circulation. Science 350, 320–324 (2015).

    CAS  Article  Google Scholar 

  27. 27.

    Olonscheck, D., Mauritsen, T. & Notz, D. Arctic sea-ice variability is primarily driven by atmospheric temperature fluctuations. Nat. Geosci. 12, 430–434 (2019).

    CAS  Article  Google Scholar 

  28. 28.

    Rayner, N. et al. Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res. Atmos. 108, 4407 (2003).

    Article  Google Scholar 

  29. 29.

    Griffies, S. M. et al. OMIP contribution to CMIP6: experimental and diagnostic protocol for the physical component of the Ocean Model Intercomparison Project. Geosci. Model Dev. 9, 3231 (2016).

    Article  Google Scholar 

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Acknowledgements

The study benefited from comments by B. Stevens, H. Haak and C. Li. T.M. received funding from the European Research Council (ERC) Consolidator Grant 770765 and the European Union’s Horizon 2020 Program Grant agreement 820829. Computational resources were made available by Deutsches Klimarechenzentrum (DKRZ) through support from the Bundesministerium für Bildung und Forschung (BMBF) and by the Swiss National Supercomputing Centre (CSCS). J.J. acknowledges support through BMBF under grants 01LP1517B (MiKliP) and 03F0729D (RACE).

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The original idea for this study was conceived by T.M., and P.K. carried out the bulk of the analysis. All the authors contributed to developing the methodology and writing the manuscript.

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Correspondence to Paul Keil.

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The authors declare no competing interests.

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Peer review information Nature Climate Change thanks Melissa Gervais and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. 1–9 and Table 1.

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Keil, P., Mauritsen, T., Jungclaus, J. et al. Multiple drivers of the North Atlantic warming hole. Nat. Clim. Chang. 10, 667–671 (2020). https://doi.org/10.1038/s41558-020-0819-8

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