We have seen elsewhere ( see methane) how atmospheric concentrations of methane
(swamp gas) during the
Holocene (last 10,000 years) are related to the extent of
wetlands especially at low (tropical) latitudes.
Here in the lowermost graph we see oxygen isotope ratios and
nitrate for the Huascaran glacier in Peru, showing an abrupt cooling at about 5200 BP.
Compare this with the graph of methane; the two are mirror
images. For other climatic indicators see the
Also shown on the upper graph are proxy paleoclimatic data from sediment cores in the Santa Barbara
basin off the coast of California, sediment bioturbidity and snail form, also indicating a discontinuity,
possibly abrupt
cooling, at 5.2k yrs BP.
References
Kennett, JP and Ingram, BL, A 20,000 yr record of ocean circulation and climate
change from the Santa Barbara basin Nature v 377 p 510 12 Oct 95.
Thompson et al Late Glacial Stage and Holocene Tropical Ice
Core Records from Huascaran, Peru Science v 269 7 July 1995.
Copyright 1996 Kirribili Press.
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