Abrupt Holocene climate change and potential response to solar forcing in western Canada
Gavin, Daniel G.; Henderson, Andrew C.G.; Westover, Karlyn S.; Fritz, Sherilyn C.; Walker, Ian R.; Leng, Melanie J.; Hu, Feng Sheng. 2011 Abrupt Holocene climate change and potential response to solar forcing in western Canada. Quaternary Science Reviews, 30 (9-10). 1243-1255. 10.1016/j.quascirev.2011.03.003Full text not available from this repository. (Request a copy)
Several abrupt climate events during the Holocene, including the widely documented oscillation at 8.2 thousand years before present (ka), are attributed to changes in the North Atlantic thermohaline circulation. Additional mechanisms, such as interactions between atmospheric circulation, ice-sheet dynamics, and the influence of solar irradiance, also have been proposed to explain abrupt climatic events, but evidence remains elusive. This study presents evidence from multi-proxy analyses on the Holocene sediments of Eleanor Lake, interior British Columbia. Climatic inferences from our decadal-resolution record of biogenic silica (BSi) abundance are supported by changes in diatom and pollen assemblages from the same core and correlations with existing regional climate records. The BSi record reveals abrupt and persistent climatic shifts at 10.2, 9.3, and 8.5 ka, the latter two of which are coeval with major collapses of the Laurentide Ice Sheet. The record also reveals a short-term cooling at 8.2 ka that is distinct from the 8.5 ka event and similar in magnitude to several other late-Holocene coolings. BSi is correlated with solar-irradiance indices (r = 0.43–0.61), but the correlation is opposite in sign to that expected from direct solar forcing and weakens after 8 ka. Possible mechanisms causing the abrupt and persistent climate changes of the early Holocene include 1) sudden losses of ice and proglacial lake extent, causing a shift in the meridional structure of atmospheric circulation, 2) a possible link between solar minima and El Niño-like conditions that are correlated with warm spring temperature in interior British Columbia, and 3) the influence of solar irradiance variability on the position of the polar jet, possibly via effects on the strength of the glacial anticyclone.
|Programmes:||BGS Programmes 2010 > NERC Isotope Geoscience Laboratory|
|Date made live:||24 Jun 2011 15:54|
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