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Dan Hammarlund

Dan Hammarlund

Professor

Dan Hammarlund

Seasonal variability in Northern Hemisphere atmospheric circulation during the Medieval Climate Anomaly and the Little Ice Age

Author

  • Thomas W. D. Edwards
  • Dan Hammarlund
  • Brandi W. Newton
  • Jesper Sjolte
  • Hans Linderson
  • Christophe Sturm
  • Natalie A. St Amour
  • Joscelyn N.L. Bailey
  • Anders L. Nilsson

Summary, in English

Here we report new reconstructions of winter temperature and summer moisture during the past millennium in southeastern Sweden, based on stable-isotope data from a composite tree-ring sequence, that further enhances our knowledge and understanding of seasonal climate variability in the Northern Hemisphere over the past millennium. Key features of these new climate proxy records include evidence for distinctive fluctuations in winter temperature in SE Sweden, superimposed upon the general pattern of cooling between the so-called Medieval Climate Anomaly (MCA) of the early millennium and the Little Ice Age (LIA) of the late millennium, as well as evidence for sustained summer wetness during the MCA, followed by drier and less variable conditions during the LIA. We also explore these new records within a circumpolar spatial context by employing self-organizing map analysis of meteorological reanalysis data to identify potential modern analogues of mid-tropospheric synoptic circulation types in the Northern Hemisphere extratropics that can reconcile varying seasonal climate states during the MCA and LIA in SE Sweden with less variable conditions in southwestern Canada, as portrayed by paleoclimate records developed in the same manner in an earlier study.

Department/s

  • Quaternary Sciences
  • MERGE: ModElling the Regional and Global Earth system

Publishing year

2017-06-01

Language

English

Pages

102-110

Publication/Series

Quaternary Science Reviews

Volume

165

Document type

Journal article

Publisher

Elsevier

Topic

  • Meteorology and Atmospheric Sciences
  • Geology

Keywords

  • Arctic Oscillation
  • Late Holocene
  • North Atlantic Oscillation
  • Northern Hemisphere extratropics
  • Paleoclimatology
  • Self-organizing maps
  • Stable isotopes
  • Synoptic circulation

Status

Published

ISBN/ISSN/Other

  • ISSN: 0277-3791