---
chapter:
  doi: 10.7930/J00863GK
  identifier: arctic
  number: 11
  report_identifier: climate-science-special-report
  sort_key: 13
  title: Arctic Changes and their Effects on Alaska and the Rest of the United States
  url: https://science2017.globalchange.gov/chapter/11/
chapter_identifier: arctic
cited_by: []
confidence: '<em>High confidence</em> in the impact of midlatitude circulation on arctic changes from the consistency between observations and models as well as a solid physical understanding.<br><br><em>Low confidence</em> on the detection of an impact of arctic warming on midlatitude climate is based on short observational data record, model uncertainty, and lack of physical understanding.'
contributors: []
evidence: 'The midlatitude circulation influences the Arctic through the transport of warm, moist air, altering the Arctic surface energy budget.<tbib>aa901e05-668b-422e-9051-ef492dbdf0c2</tbib><sup>,</sup><tbib>9eef4c2e-2b3f-4386-af91-10e83338a398</tbib><sup>,</sup><tbib>289576a2-4f02-47e2-9a46-567482c10722</tbib><sup>,</sup><tbib>1e9f503b-a791-4267-acbe-11ae80ef29a8</tbib> The intrusion of warm, moist air from midlatitudes increases downwelling longwave radiation, warming the arctic surface and hindering wintertime sea ice growth.<tbib>4a7689c2-e1b8-4ef9-a805-23e48a8ce4df</tbib><sup>,</sup><tbib>7a2bd7c3-58ef-47d0-9f3f-f758000eb8b7</tbib> Emerging research provides a new understanding of the importance of synoptic time scales and the episodic nature of midlatitude air intrusions.<tbib>4a7689c2-e1b8-4ef9-a805-23e48a8ce4df</tbib><sup>,</sup><tbib>37084560-ef67-4df8-a7a5-297582db124c</tbib><sup>,</sup><tbib>39754a3f-cc3a-4cc9-8eac-23611de42eec</tbib> The combination of recent observational and model-based evidence as well as the physical understanding of the mechanisms of midlatitude circulation effects on arctic climate supports this Key Finding. <br><br> In addition, research on the impact of arctic climate on midlatitude circulation is rapidly evolving, including observational analysis and modeling studies. Multiple observational studies provide evidence for concurrent changes in the Arctic and Northern Hemisphere large-scale circulation changes.<tbib>36734ba2-a8b8-419b-99ad-775a948d2408</tbib><sup>,</sup><tbib>b7233b5f-ea63-454c-948f-3a14797c355b</tbib><sup>,</sup><tbib>e94a833d-caff-4c43-9ebd-daa3c8bf17a7</tbib> Further, modeling studies demonstrate that arctic warming can influence the midlatitude jet stream and storm track.<tbib>8686421f-6c0c-4608-bc94-a550fe22514f</tbib><sup>,</sup><tbib>625f0fff-b107-4dd0-95ae-0eba38aada7c</tbib><sup>,</sup><tbib>b7233b5f-ea63-454c-948f-3a14797c355b</tbib><sup>,</sup><tbib>29ef1bb5-092f-4a1b-ab0e-1fdc5a0e2ae0</tbib> However, attribution studies indicate that the observed midlatitude circulation changes over the continental United States are smaller than natural variability and are therefore not detectable in the observational record.<tbib>9eef4c2e-2b3f-4386-af91-10e83338a398</tbib><sup>,</sup><tbib>1e9f503b-a791-4267-acbe-11ae80ef29a8</tbib><sup>,</sup><tbib>a3628a75-8c8e-49e9-ab07-d3a24017225a</tbib><sup>,</sup><tbib>e393f5f9-08a1-4c08-9ec6-8e445e988b83</tbib> This disagreement between independent studies using different analysis techniques and the lack of understanding of the physical mechanism(s) supports this Key Finding.'
files: []
gcmd_keywords: []
href: https://data.globalchange.gov/report/climate-science-special-report/chapter/arctic/finding/key-finding-11-5.yaml
identifier: key-finding-11-5
ordinal: 5
parents:
  - activity_uri: ~
    label: 'figure -.2: Confidence / Likelihood'
    note: ''
    publication_type_identifier: figure
    relationship: prov:wasDerivedFrom
    url: /report/climate-science-special-report/chapter/front-matter/figure/confidence---likelihood
process: 'The midlatitude circulation has influenced observed arctic temperatures, supported by recent observational and model-based evidence as well as the physical understanding from emerging science. In turn, confidence is low regarding the mechanisms by which observed arctic warming has influenced the midlatitude circulation and weather patterns over the continental United States, due to the disagreement between numerous studies and a lack of understanding of the physical mechanism(s). Resolving the remaining questions requires longer data records and improved understanding and modeling of physics in the Arctic. The influence of arctic changes on U.S. weather over the coming decades remains an open question with the potential for significant impact.'
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report_identifier: climate-science-special-report
statement: 'Atmospheric circulation patterns connect the climates of the Arctic and the contiguous United States. Evidenced by recent record warm temperatures in the Arctic and emerging science, the midlatitude circulation has influenced observed arctic temperatures and sea ice (<em>high confidence</em>). However, confidence is <em>low</em> regarding whether or by what mechanisms observed arctic warming may have influenced the midlatitude circulation and weather patterns over the continental United States. The influence of arctic changes on U.S. weather over the coming decades remains an open question with the potential for significant impact.'
uncertainties: A major limiting factor is our understanding and modeling of natural climate variability in the Arctic. Longer data records and a better understanding of the physical mechanisms that drive natural climate variability in the Arctic are required to reduce this uncertainty. The inability of climate models to accurately capture interactions between sea ice and the atmospheric circulation and polar stratospheric processes limits our current understanding.
uri: /report/climate-science-special-report/chapter/arctic/finding/key-finding-11-5
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