Clim. Past Discuss., 8, 595-620, 2012
www.clim-past-discuss.net/8/595/2012/
doi:10.5194/cpd-8-595-2012
© Author(s) 2012. This work is distributed
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This discussion paper has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP.
Investigating late Holocene variations in hydroclimate and the stable isotope composition of precipitation using southern South American peatlands: a hypothesis
T. J. Daley1, D. Mauquoy2, and F. M. Chambers3
1School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth, PL4 8AA, UK
2School of Geosciences, University of Aberdeen, Elphinstone Road, Aberdeen, AB24 3UF, UK
3Centre for Environmental Change and Quaternary Research, School of Natural and Social Sciences, Francis Close Hall, University of Gloucestershire, Cheltenham, GL50 4AZ, UK

Abstract. Ombrotrophic raised peatlands provide an ideal archive for integrating late Holocene records of variations in hydroclimate and the estimated stable isotope composition of precipitation with recent instrumental measurements. Modern measurements of mean monthly surface air temperature, precipitation and δD and δ18O values in precipitation from the late twentieth and early twenty-first centuries provide a short but invaluable record with which to investigate modern relationships between these variables, thereby enabling improved interpretation of the peatland palaeodata. Data from two stations in the Global Network for Isotopes in Precipitation (GNIP) from Tierra del Fuego (Punta Arenas, Chile and Ushuaia, Argentina) were analysed for the period 1982 to 2008. In both locations, δD and δ18O values have decreased in response to quite different trends in local surface air temperature and total precipitation amount. At Ushuaia, the fall in δ18O values is associated with an increase in the mean annual amount of precipitation. At Punta Arenas, the fall in δ18O values is weakly associated with decrease in the precipitation amount and an increase in local temperatures. The pattern in both records is consistent with an increase in the zonal intensity of the southern westerly wind belt. These regional differences, observed in response to a known driver, should be detectable in peatland sites close to the GNIP stations. There is currently insufficient availability of suitably temporally resolved data to test for these regional differences over the last 3000 yr. Existing peatland palaeoclimate data from two sites near Ushuaia, however, provide evidence for changes in the late Holocene that are consistent with the pattern observed in modern observations. Furthermore, the records suggest synchroneity in millennial-scale oscillations between the Northern and Southern Hemispheres.

Citation: Daley, T. J., Mauquoy, D., and Chambers, F. M.: Investigating late Holocene variations in hydroclimate and the stable isotope composition of precipitation using southern South American peatlands: a hypothesis, Clim. Past Discuss., 8, 595-620, doi:10.5194/cpd-8-595-2012, 2012.
 
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