Abundance, Distribution and Stable Carbon Isotope Composition of Leaf-waxes (n-alkanes) From Surface Lake Sediments Along a Climatological Gradient on the Western Side of the Southern Andes
Abstract
The climate in central to southern South America on the western side of the Andes is projected to become significantly warmer and drier over the next several decades to centuries in response to climate change. In addition, model projections show a poleward change and intensification of the Southern Hemisphere Westerly Winds (SWW) and associated storm tracks, the main source of moisture (>7000 mm/yr) to the southern South American continent, as a result of global warming. Such anthropogenic climate changes are superimposed on natural climate variability, which is less well understood in vast, remote and pristine areas of southern South America where meteorological data are absent or scarce and low in spatial and temporal resolution. Thus, we need to turn to proxies and paleoclimate records to gather data on climate variability in the region, which can be compared to climate models to evaluate their performance and help validate future climate projections. Sedimentary leaf wax derived long chain alkanes (>C25) and alkanoic acids (>C24) are among the most long-lived and widely utilized proxies of terrestrial organic matter. While sedimentary leaf wax abundance and distribution (e.g. average carbon chain length, ACL) have been intensively used in paleoclimate studies, recent studies of modern plant waxes have challenged their use as reliable indicators of vegetation. Here we discuss the abundance, distribution and stable carbon isotope composition of leaf-wax n-alkanes from a suite lake surface sediment (core-top) samples spanning the transition from a Mediterranean climate with a patchwork of cultivated vegetation, pastureland, conifers in central Chile to a rainy temperate climate dominated by broadleaf deciduous and evergreen forest. Data are correlated against latitudinal and orographic climatic trends and climatology (mean annual precipitation and temperature) using monthly gridded reanalysis products of the Climate Forecast System Reanalysis (CFSR), based on the NCEP global forecast model and meteorological stations available in the region, from January 1979 to December 2010 with a 0.5° horizontal resolution.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP51C1160C
- Keywords:
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- 0458 Limnology;
- BIOGEOSCIENCESDE: 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 1854 Precipitation;
- HYDROLOGYDE: 1855 Remote sensing;
- HYDROLOGY