Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Reduced efficiency of the Barents Sea cooling machine


Dense water masses from the Barents Sea are an important part of the Arctic thermohaline system. Here, using hydrographic observations from 1971 to 2018, we show that the Barents Sea climate system has reached a point where ‘the Barents Sea cooling machine’—warmer Atlantic inflow, less sea ice, more regional ocean heat loss—has changed towards less-efficient cooling. Present change is dominated by reduced ocean heat loss over the southern Barents Sea as a result of anomalous southerly winds. The outflows have accordingly become warmer. Outflow densities have nevertheless remained relatively unperturbed as increasing salinity appears to have compensated the warming inflow. However, as the upstream Atlantic Water is now observed to freshen while still relatively warm, we speculate that the Barents Sea within a few years may export water masses of record-low density to the adjacent basins and deep ocean circulation.

This is a preview of subscription content

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: The Barents Sea cooling machine.
Fig. 2: The Barents Sea temperature changes.
Fig. 3: Ocean heat loss in the Barents Sea.
Fig. 4: BSW changes.

Data availability

This study covering the period 1971–2018 included 322,812 vertical profiles of T and S from the joint Norwegian (IMR)–Russian (PINRO) ecosystem surveys performed annually during fall (August–September). The Norwegian data are available at The Russian data are available for this study through a bilateral data exchange but are generally not publicly available. The ERA–Interim atmospheric reanalyses are available at The time series of volume transport Supplementary Fig. 3 are available at


  1. 1.

    Årthun, M., Eldevik, T., Smedsrud, L. H., Skagseth, Ø. & Ingvaldsen, R. B. Quantifying the influence of Atlantic heat on Barents Sea ice variability and retreat. J. Clim. 25, 4736–4743 (2012).

    Google Scholar 

  2. 2.

    Skagseth, Ø. et al. in Arctic–Subarctic Ocean Fluxes: Defining the Role of the Northern Seas in Climate (eds Dickson, R. et al.) 45–64 (Springer, 2008).

  3. 3.

    Levitus, S., Matishov, G., Seidov, D. & Smolyar, I. Barents Sea multidecadal variability. Geophys. Res. Lett. 36, L19604 (2009).

    Google Scholar 

  4. 4.

    Carton, J. A., Chepurin, G. A., Reagan, J. & Hakkinen, S. Interannual to decadal variability of Atlantic Water in the Nordic and adjacent seas. J. Geophys. Res. 116, C11035 (2011).

    Google Scholar 

  5. 5.

    Yashayaev, I. & Seidov, D. The role of the Atlantic Water in multidecadal ocean variability in the Nordic and Barents Seas. Prog. Oceanogr. 132, 68–127 (2015).

    Google Scholar 

  6. 6.

    Chernokulsky, A. V. et al. Climatology and interannual variability of cloudiness in the Atlantic Arctic from surface observations since the late nineteenth century. J. Clim. 30, 2103–2120 (2017).

    Google Scholar 

  7. 7.

    Woods, C. & Caballero, R. The role of moist intrusions in winter Arctic warming and sea ice decline. J. Clim. 29, 4473–4485 (2016).

    Google Scholar 

  8. 8.

    IPCC Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, 2013).

  9. 9.

    Onarheim, I. H. & Årthun, M. Toward an ice-free Barents Sea. Geophys. Res. Lett. 44, 8387–8395 (2017).

    Google Scholar 

  10. 10.

    Smedsrud, L. H. et al. The role of the Barents Sea in the Arctic climate system. Rev. Geophysics 51, 415–449 (2013).

    Google Scholar 

  11. 11.

    Schauer, U., Loeng, H., Rudels, B., Ozhigin, V. K. & Dieck, W. Atlantic water flow through the Barents and Kara seas: Deep Sea Res. Part 1 49, 2281–2298 (2002).

  12. 12.

    Schauer, U., Muench, R. D., Rudels, B. & Timokhov, L. Impact of eastern Arctic shelf waters on the Nansen Basin intermediate layers. J. Geophys. Res. 102, 3371–3383 (1997).

    Google Scholar 

  13. 13.

    Lozier, M. S. et al. A sea change in our view of overturning in the subpolar North Atlantic. Science 363, 516–521 (2019).

    CAS  Google Scholar 

  14. 14.

    Mauritzen, C. Production of dense overflow waters feeding the North Atlantic across the Greenland–Scotland Ridge. Part 1: evidence for a revised circulation scheme: Deep Sea Res. Part 1 43, 769–806 (1996).

  15. 15.

    Aagaard, K., Swift, J. H. & Carmack, C. Thermohaline circulation in the Arctic Mediterranean Seas. J. Geophys. Res. 90, 4833–4846 (1985).

    Google Scholar 

  16. 16.

    Lien, V. S., Schlichtholz, P., Skagseth, Ø. & Vikebø, F. B. Wind-riven Atlantic Water flow as a direct mode for reduced Barents Sea ice cover. J. Clim. 30, 803–661 812 (2017).

    Google Scholar 

  17. 17.

    Lien, V. S. & Trofimov, A. G. Formation of Barents Sea Branch Water in the north-eastern Barents Sea. Polar Res. 32, 18905 (2013).

    Google Scholar 

  18. 18.

    Herbaut, C., Houssais, M.-N., Close, S. & Blaizot, A.-C. Two wind-driven modes of winter sea ice variability in the Barents Sea. Deep Sea Res. Part I 106, 97–115 (2015).

    Google Scholar 

  19. 19.

    Barton, B. I., Lenn, Y. D. & Lique, C. Observed Atlantification of the Barents Sea causes the polar front to limit the expansion of winter sea ice. J. Phys. Oceanogr. 48, 1849–1866 (2018).

    Google Scholar 

  20. 20.

    Gawarkiewicz, G. & Plueddemann, A. J. Topographic control of thermohaline frontal structure in the Barents Sea polar front on the south flank of Spitsbergen Bank. J. Geophys. Res. 100, 4509–4524 (1995).

    Google Scholar 

  21. 21.

    Skagseth, Ø. Recirculation of Atlantic Water in the western Barents Sea. Geophys. Res. Lett. 35, L11606 (2008).

    Google Scholar 

  22. 22.

    Midttun, L. Formation of dense bottom water in the Barents Sea. Deep Sea Res. 32, 1233–1241 (1985).

    Google Scholar 

  23. 23.

    Blindheim, J. Cascading of Barents Sea bottom water into the Norwegian Sea. Rapp. P. V. Reun. Cons. Int. Explor. Mer. 188, 49–58 (1989).

    Google Scholar 

  24. 24.

    Helland-Hansen, B. & Nansen, F. The Norwegian Sea. Its Physical Oceanography Based Upon the Norwegian Researches 1900–1904. Vol. 2 (Det Mallingske bogtrykkeri, 1909).

  25. 25.

    Smedsrud, L. H., Ingvaldsen, R. B., Nilsen, J. E. Ø. & Skagseth, Ø. Heat in the Barents Sea: transport, storage, and surface fluxes. Ocean Sci. 6, 219–234 (2010).

    Google Scholar 

  26. 26.

    Onarheim, I. H., Eldevik, T., Arthun, M., Ingvaldsen, R. B. & Smedsrud, L. H. Skillful prediction of Barents Sea ice cover. Geophys. Res. Lett. 42, 5364–5371 (2015).

    Google Scholar 

  27. 27.

    Schlichtholz, P. Subsurface ocean flywheel of coupled climate variability in the Barents Sea hotspot of global warming. Sci. Rep. 9, 13692 (2019).

    Google Scholar 

  28. 28.

    Long, Z. & Perrie, W. Changes in ocean temperature in the Barents Sea in the twenty-first century. J. Clim. 30, 5901–5921 (2017).

    Google Scholar 

  29. 29.

    Ingvaldsen, R. B., Asplin, L. & Loeng, H. The seasonal cycle in the Atlantic transport to the Barents Sea during the years 1997–2001. Cont. Shelf Res. 24, 1015–1032 (2004).

    Google Scholar 

  30. 30.

    Dmitrenko, I. A. et al. Heat loss from the Atlantic Water layer in the St. Anna Trough (northern Kara Sea): causes and consequences. Ocean Sci. 10, 719–730 (2014).

    Google Scholar 

  31. 31.

    Polyakov, I. V. et al. Greater role for Atlantic inflows on sea-ice loss in the Eurasian Basin of the Arctic. Ocean. Sci. 356, 285–291 (2017).

    CAS  Google Scholar 

  32. 32.

    Lind, S., Ingvaldsen, R. B. & Furevik, T. Arctic warming hotspot in the northern Barents Sea linked to declining sea-ice import. Nat. Clim. Change 8, 634–639 (2018).

    Google Scholar 

  33. 33.

    Shapiro, G. I., Huthnance, J. M. & Ivanov, V. V. Dense water cascading off the continental shelf. J. Geophys. Res. Oceans 108, 3390 (2003).

  34. 34.

    Ivanov, V. V., Shapiro, G. I., Huthnance, J. M., Aleynik, D. L. & Golovin, P. N. Cascades of dense water around the world ocean. Prog. Oceanogr. 60, 47–98 (2004).

    Google Scholar 

  35. 35.

    Ding, Q. et al. Influence of high-latitude atmospheric circulation changes on summertime Arctic sea ice. Nat. Clim. Change 7, 289–295 (2017).

    Google Scholar 

  36. 36.

    Årthun, M., Eldevik, T. & Smedsrud, L. H. The role of Atlantic heat transport in future Arctic winter sea ice loss. J. Clim. 32, 3327–3341 (2019).

    Google Scholar 

  37. 37.

    Inoue, J., Hore, M. E. & Takaya, K. The role of the Barents Sea ice in the wintertime cyclone track and emergence of a Warm-Arctic Cold-Siberian anomaly. J. Clim. 25, 2561–2568 (2012).

    Google Scholar 

  38. 38.

    Shepherd, T. G. Atmospheric circulation as a source of uncertainty in climate change projections. Nat. Geosci. 7, 703–708 (2014).

    CAS  Google Scholar 

  39. 39.

    Boisvert, L. N., Petty, A. A. & Stroeve, J. C. The impact of the extreme winter 2015/16 Arctic cyclone on the Barents-Kara seas. Mon. Weather Rev. 144, 4279–4287 (2016).

    Google Scholar 

  40. 40.

    Mori, M. et al. A reconciled estimate of the influence of Arctic sea-ice loss on recent Eurasian cooling. Nat. Clim. Change 9, 123–129 (2019).

    Google Scholar 

  41. 41.

    Screen, J. A. & Blackport, R. Is sea-ice-driven Eurasian cooling too weak in models? Nat. Clim. Change 9, 934–936 (2019).

    Google Scholar 

  42. 42.

    Mork, K. A., Skagseth, Ø. & Søiland, H. Recent warming and freshening of the Norwegian Sea observed by Argo data. J. Clim. 32, 3695–3705 (2019).

    Google Scholar 

  43. 43.

    Holliday, N. P. et al. Ocean circulation causes the largest freshening event for 129 years in eastern subpolar North Atlantic. Nat. Commun. 11, 585 (2020).

    CAS  Google Scholar 

  44. 44.

    Furevik, T. Annual and interannual variability of the Atlantic Water temperatures in the Norwegian and Barents seas: 1980–1996. Deep Sea Res. Part I 48, 383–404 (2001).

    Google Scholar 

  45. 45.

    Broomé, S. & Nilsson, J. Shear dispersion and delayed propagation of temperature anomalies along the Norwegian Atlantic Slope Current. Tellus A 70, 1453215 (2018).

    Google Scholar 

  46. 46.

    Dee, D. P. et al. The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q. J. R. Meteorol. Soc. 137, 553–597 (2011).

    Google Scholar 

  47. 47.

    Preisendorfer, R. W. Principal Component Analysis in Meteorology and Oceanography (Elsevier, 1988).

  48. 48.

    Bretherton, F., Davis, R. E. & Fandry, C. B. A technique for objective analysis and design of oceanographic experiments applied to MODE–73. Deep Sea Res. 23, 559–582 (1976).

    Google Scholar 

  49. 49.

    Lavender, K. V., Owens, W. B. & Davis, R. E. The mid-depth circulation of the subpolar North Atlantic Ocean as measured by subsurface floats. Deep Sea Res. Part I 52, 767–785 (2005).

    Google Scholar 

  50. 50.

    Voet, G., Quadfasel, D., Mork, K. A. & Søiland, H. The mid-depth circulation of the Nordic Seas derived from profiling float observations. Tellus A 62, 516–529 (2010).

    Google Scholar 

Download references


This work received funding from the Norwegian Research Council projects Pathway (grant 263223) and Nansen Legacy (grant 276730), the Fram Centre project ICEHOT and the Trond Mohn Foundation (project BFS2018TMT01).

Author information




Ø.S. did the data analysis. All authors contributed to the ideas and the writing of the manuscript.

Corresponding author

Correspondence to Øystein Skagseth.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Climate Change thanks Vladimir Ivanov, Kerstin Jochumsen and Zhenxia Long for their contribution to the peer review of this work.

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

Extended data

Extended Data Fig. 1 Hydrographic data coverage.

The Barents Sea is divided into a 1° longitude by 0.5° latitude grid and we show the fraction of years to the whole (1971-2018) period where at least one observation exists within 55 km distance from the grid point. The unit is in [%]. The black lines show the areas used in Figs. 2 and 4 and Supplementary Fig. 2.

Extended Data Fig. 2 The Barents Sea along-stream cooling.

Temperature difference between regions R1-R2, R2-R3, and R3-R4 in a) the layer 0-30 m, and b) in the layer 100-200 m. The regions R1-4 are shown in Fig. 2. A Statistical test if the along-stream cooling of Atlantic Water is significantly different during the two periods 1971-1999 and 2000-2018 are given in Supplementary Table. 1.

Extended Data Fig. 3 Atlantic Water inflow to the Barents Sea.

The estimates represent one-year mean values centred about 1st Jan and are based on an array of current meters in the western Barents Sea at about 20o E between 71o 30′–73o 30′N. AW is defined as water with temperature exceeding 3oC (see for example Ingvaldsen et al.29). The trend (dashed line) is 0.2 Sv over the period 1998 to 2018 and is not significant. Vertical bars indicate a guesstimate of the standard error. To estimate this we use total monthly error attributed to the individual current meters. The standard error of the annual means is then given by: \({\boldsymbol{e}}_{{\boldsymbol{annual}}} = \sqrt {\frac{{\mathop {\sum }\nolimits_{{\boldsymbol{i}} = 1}^{\boldsymbol{N}} {\boldsymbol{e}}_{\boldsymbol{i}}^2}}{{\boldsymbol{n}}}}\), and depends on the number of current meters (N) that varies over time and the time averaging, here number of months n=12. Sv=106 m3/s.

Extended Data Fig. 4 Statistical test of changes in the along-stream cooling of Atlantic Water.

The table show p-values based on a Welch test to investigate if the mean values are significantly different during the two periods 1971-1999 and 2000-2018. p-values < 0.05 are in bold (significant at the 95% level), and ± indicates if the cooling has become stronger/weaker during the recent compared to the early period. The definitions of the ‘Cold’ and ‘Warm’ periods (based on Supplementary Fig. 2) is subjective. However, as long as we avoid extending the ‘Warm’ period with many years into the preceding ‘Cold’ period the statistical results appear robust.

Supplementary information

Supplementary Information

Supplementary information, data, methods, data availability, Figs. 1–3 and Table 1.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Skagseth, Ø., Eldevik, T., Årthun, M. et al. Reduced efficiency of the Barents Sea cooling machine. Nat. Clim. Chang. 10, 661–666 (2020).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing