EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Divergent consensuses on Arctic amplification influence on mid-latitude severe winter weather

Judah Cohen1, Xiangdong Zhang2, and the Arctic mid-latitude linkages review paper*
Judah Cohen and Xiangdong Zhang and the Arctic mid-latitude linkages review paper
  • 1AER, Inc., Lexington, MA, United States of America (
  • 2University of Alaska, AK, United States of America
  • *A full list of authors appears at the end of the abstract

The Arctic has warmed more than twice as fast as the global average since the late 20th century, a phenomenon known as Arctic amplification (AA).  Recently, there have been significant advances in understanding the physical contributions to AA and progress has been made in understanding the mechanisms linking AA to mid-latitude weather variability.  Observational studies overwhelmingly support that AA is contributing to winter continental cooling.  While Arctic warming is strongest at the surface, it extends throughout the mid-troposphere. In addition, the sea ice loss and associated warming is not uniform across the Arctic, but rather regionally focused including in the Barents-Kara Seas, a key region for disrupting the polar vortex.  The probability of severe winter weather increases across the Northern Hemisphere continents following polar vortex disruptions.  While some model experiments support the observational evidence, the majority of modeling results show little connection between AA and severe mid-latitude weather. Rather the excess warming generated in the Arctic due to sea ice loss and other mechanisms is not redistributed vertically in model simulations, but rather horizontally suggesting the export of excess heating from the Arctic to lower latitudes.  Divergent conclusions between model and observational studies, and even intra-model studies, continue to obfuscate a clear understanding of how AA is influencing mid-latitude weather.

Arctic mid-latitude linkages review paper:

J. Francis, T. Jung, R. Kwok, J. Overland, T. J. Ballinger, U. S. Bhatt, H. W. Chen, D. Coumou, S. Feldstein1, H. Gu, D. Handorf, G. Henderson, M. Ionita, M. Kretschmer, F. Laliberte, S. Lee, H. W. Linderholm, W. Maslowski, Y. Peings, K. Pfeiffer, I. Rigor, T. Semmler, J. Stroeve, P. C. Taylor, S. Vavrus, T. Vihma, S. Wang, M. Wendisch, Y. Wu, J. Yoon

How to cite: Cohen, J. and Zhang, X. and the Arctic mid-latitude linkages review paper: Divergent consensuses on Arctic amplification influence on mid-latitude severe winter weather, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2748,, 2020

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  • CC1: Comment on EGU2020-2748, David Docquier, 05 May 2020

    Dear Judah,

    Thanks for your interesting work. I have a couple of questions:

    1) What do you exactly represent in Slides 14 (bar plot) and 15 (maps of T anomaly)?

    2) In slide 22, you say that 'most dynamical models support that a warmer Arctic does not significantly impact polar vortex and either has little impact on mid-latitude weather or contributes to milder winters'. Is that really the case or is it rather that models do not agree?

    Thank you for your feedback.


  • AC1: Comment on EGU2020-2748, Judah Cohen, 05 May 2020

    Thank you David for your questions.  The bar graph on slide 14 represents number of studies. So for example the first bar of "47" represents 47 observational studies that conclude that Arctic amplification is contributing to colder continents.  Slide 15 shows the regression of regional and pan Arctic temperatures with hemsipheric temperatures from the observations in the first row and models in the second row.  In the third row are shown modeling results for the hemispheric temperature response to regional and pan Arctic sea ice pertubations.

    • CC3: Reply to AC1, David Docquier, 05 May 2020

      Thanks for your quick reply.

      For Slide 15, following your explanation, shouldn't then the quantity shown be unitless? Or I misunderstood something. And could you say what models you used in the 2nd and 3rd rows? Are the models used in the 3rd row similar to the 2nd row? I'm a bit confused by the meaning of this figure.



      • AC3: Reply to CC3, Judah Cohen, 05 May 2020

        Hi David,

        You can see a more complete explanation of the slide in Figure 3 from our recent review paper.  You can view the paper at this link:

        Please let me know if the link doesn't work.


        • CC4: Reply to AC3, David Docquier, 05 May 2020

          Yes, I've just seen it, I'm going through it. Congrats for this very nice piece of work by the way.



          • AC4: Reply to CC4, Judah Cohen, 05 May 2020

            Thank you!


  • AC2: Comment on EGU2020-2748, Judah Cohen, 05 May 2020

    David, In regards to your second question the simulated response to sea ice loss is quited varied from warming the continents, to no response to collign the continents.  But this large mdoel spread only exists in perturbation experiments.  In model control runs such as AMIP and CMIP the response to sea ice loss is fairly cinsistent - widepread continental warming.

    • CC2: Reply to AC2, David Docquier, 05 May 2020

      Thanks for clarifying.