Climate Change Research Today is a free monthly online journal that collates and summarizes the latest research about Climate Change, including details on causes, effects, impact, facts, myths, information.

Clay aquitards as archives of holocene paleoclimate: delta18O and thermal profiling.

Hendry MJ, Woodbury AD

Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada.

Paleoclimatic conditions in the Holocene were reconstructed from a detailed vertical profile of pore water delta(18)O and a series of downhole thermal profiles at a thick, hydrogeologically simple, aquitard research site in the Northern Great Plains of Saskatchewan. Reconstructions were obtained using the theory of one-dimensional diffusive transport and an empirical Bayesian inversion technique. Inversion of the delta(18)O profile shows that input signal consists of a sudden increase of +6 per thousand (corresponding to a temperature increase of about 18 degrees C) at about 12,000 years before present (BP), after which no measurable change in delta(18)O is apparent to present day. This research shows, at this location, that there is no evidence of large amplitude temperature shifts in the Holocene and supports the commonly used assumption in ground water studies of constant atmospheric delta(18)O values throughout the Holocene. Inversion of the temperature profiles suggests the ground surface temperature increased primarily in the last half of the 20th century, with a peak temperature (about 3 degrees C) circa 1990. For both profiles, the ability to resolve historical variability decays rapidly with time. For the temperature profiles, the decay in resolution precluded the development of reliable estimates of climatic conditions prior to about 1950 and, in the case of the delta(18)O profile, it prevented the precise definition of climate changes (e.g., Hypsithermal and Little Ice Age) in the Holocene.

Published 1 November 2007 in Ground Water, 45(6): 683-91.
Full-text of this article is available online (may require subscription).

© 2004-2008 Climate Change Research Today. All Rights Reserved.