Multiple abrupt climate changes in the western hemisphere during the past 50,000 years, and their implications concerning the response of vegetation to changing atmospheric chemistry

Journal Article · Thu Jun 01 04:00:00 EDT 1995 · Bulletin of the Ecological Society of America

OSTI ID:95821

Jacobson, Jr, G L ^[1]; Grimm, E C ^[2]

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1. Univ. of Maine, Orono, ME (United States)
2. Illinois State Museum, Springfield, IL (United States)

Independent evidence spanning the last 50,000 years from ice cores, ocean sediments, and detailed glacial-geologic investigations implies multiple. large warm/cool oscillations with a frequency of ca. 3000 years through much of the Western Hemisphere. Paleoecological studies at sites in North America and the west coast of South America reveal major, synchronous changes in vegetation corresponding to many of these high-frequency changes in climate. Sequences on both sides of the equator culminate in substantial warming at 14 ka BP and a brief cooling at ca. 11 ka BP just prior to the final onset of Holocene warming. The high-frequency climate oscillations are not explained by {open_quotes}Milankovitch{close_quotes} cycles in solar insolation or by changes in thermohaline ocean circulation. Rather, these changes in climate and the attendant synchronous, broad-scale responses of vegetation indicate a global atmospheric forcing. However, that forcing is apparently also distinct from changing concentrations of atmospheric CO2 (as represented in the Vostok ice-core data). High-resolution CO2 data, such as that from the new Greenland ice cores, will be required before critical assessments of plant-physiological responses to past atmospheric changes can be carried out.

• OSTI ID: 95821
• Report Number(s): CONF-9507129--
• Journal Information: Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 2 Vol. 76; ISSN BECLAG; ISSN 0012-9623
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
ATMOSPHERIC CHEMISTRY
BIOLOGICAL EFFECTS
CLIMATIC CHANGE
GLACIERS
GROUND COVER
NORTH AMERICA
PALEOCLIMATOLOGY
PHENOLOGY
RESPONSE FUNCTIONS