Wednesday, August 21, 2013

Paper finds another non-hockey-stick in Bolivia

A paper published in Science finds another non-hockey-stick in Bolivia with temperatures during the Medieval, Roman, Egyptian, Minoan, and Holocene Climate Optimum all higher than modern temperatures.

Top dark line in graph is d180, a proxy for temperature and precipitation. Higher values represent higher temperatures. Horizontal axis is thousands of years before the present.
A 25,000 year tropical climate history from Bolivian ice cores 
Science, Volume 282(5295), 1858-1864, 1998.

Thompson, L.G., M.E. Davis, E.M.Thompson,
T.A.Sowers, K.A. Henderson, V.S. Zagorodnov,
P.N. Lin, V.N. Mikhalenko, R.K. Campen,
J.F.Bolzan, J.Cole-Dai and B.Francou.

Ice cores that were recovered from the summit of Sajama mountain in Bolivia provide carbon-14-dated tropical records and extend to the Late Glacial Stage (LGS). Oxygen isotopic ratios of the ice decreased 5.4 per mil between the Early Holocene and Last Glacial Maximum, which is consistent with values from other ice cores. The abrupt onset and termination of a Younger Dryas-type event suggest atmospheric processes as the probable drivers. Regional accumulation increased during the LGS, during deglaciation and over the past 3000 years, which is concurrent with higher water levels in regional paleolakes. Unlike polar cores, Sajama glacial ice contains eight times less dust than the Holocene ice, which reflects wetter conditions and extensive snow cover.

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