The role of seasonality in abrupt climate change

George H. Denton, Richard B. Alley, Gary C. Comer, Wallace S. Broecker

Research output: Contribution to journalArticle

362 Scopus citations

Abstract

A case is made that seasonality switches dominated by wintertime were instrumental in abrupt climate changes in the North Atlantic region during the last glaciation and into the Holocene. The primary evidence comes from mismatches between mean annual temperatures from Greenland ice cores in comparison with snowline changes in East Greenland, northern Europe, and North America. The most likely explanation is a shutdown (or reduction in strength) of the conveyor. This allows the spread of winter sea ice across the North Atlantic, thus causing the northern region to experience much colder winters. Because they mimic the Greenland temperature rather than the snowline signal, changes in the Atlantic Intertropical Convergence Zone and the Asian monsoon may also share a winter linkage with Greenland. Thus the paleoclimate record is consistent with the notion that a huge continental sector of the Northern Hemisphere, stretching from Greenland to Asia, was close to an extreme winter threshold during much of the last glaciation. Winter climate crossed this threshold repeatedly, with marked changes in seasonality that may well have amplified and propagated a signal of abrupt change throughout the hemisphere and into the tropics.

Original languageEnglish (US)
Pages (from-to)1159-1182
Number of pages24
JournalQuaternary Science Reviews
Volume24
Issue number10-11
DOIs
StatePublished - May 1 2005

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Ecology, Evolution, Behavior and Systematics
  • Archaeology
  • Archaeology
  • Geology

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