climatology; Climate change; sedimentology; Geochemistry; Quaternary; Limnology; South America; Holocene
Neukom R, Luterbacher J, Villalba R, Küttel M, Frank D, Jones PD, Grosjean M, Wanner H, Aravena J-C, Black DE, Christie DA, D'Arrigo R, Lara A, Morales M, Soliz-Gamboa C, Srur A, Urrutia R, von Gunten L (2011), Multiproxy summer and winter surface air temperature field reconstructions for southern South America covering the past centuries, in Climate Dynamics
, 37(1), 35-51.
Neukom R, Luterbacher J, Villalba R, Kttel M, Frank D, Jones PD, Grosjean M, Esper J, Lopez L, Wanner H (2010), Multi-centennial summer and winter precipitation variability in southern South America, in Geophysical Research Letters
, 37(14), 1-6.
von Gunten L, Grosjean M, Beer J, Grob P, Morales A, Urrutia R (2009), Age modeling of young non-varved lake sediments: Methods and limits. Examples from two lakes in Central Chile, in Journal of Paleolimnology
, 42(3), 401-412.
Villalba R, Grosjean M, Kiefer T (2009), Long-term multi-proxy climate reconstructions and dynamics in South America (LOTRED-SA): State of the art and perspectives, in Palaeogeography, Palaeoclimatology, Palaeoecology
, 281(3-4), 175-179.
von Gunten L, Grosjean M, Eggenberger U, Grob P, Urrutia R, Morales A (2009), Pollution and eutrophication history AD 1800-2005 as recorded in sediments from five lakes in Central Chile, in Global and Planetary Change
, 68(3), 198-208.
Elbert Julie, Grosjean Martin, von Gunten Lucien, Urrutia Roberto, Fischer Daniela, Wartenburger Richard, Ariztegui Daniel, Fujak Marian, Hamann Yvonne, Quantitative high-resolution winter (JJA) precipitation reconstruction from varved sediments of Lago Plomo 47°S, Patagonian Andes, AD 1530-2002, in The Holocene
Seasonal to annual quantitative reconstructions of spatially-explicit climate state variables for the last 1000 years are recognized as one of the primary targets for current climate research (IGBP-PAGES / WCRP-CLIWAR). This builds on the rationale that knowledge about the natural, forced and stochastic variability at different scales is critical (i) to discriminate the human fingerprint on the global climate system during the 20th century (detection and attribution) and (ii) to reduce uncertainty for ecological, societal and economic risks when natural variability and anthropogenic forcings are superposed in the future climate.While substantial advancements were made (i) in past global climate modelling, (ii) in northern hemispheric temperature reconstructions for the last 1000 years, and (iii) in the evaluation of statistical multi-proxy reconstruction techniques, it is increasingly recognized that the limiting factor to further scientific advancement is actually the lack of robust paleoclimate data series at an adequate quality and representative spatial distribution. This is strikingly evident for the southern hemisphere which is, paradoxically, the area with theoretically best chances for greenhouse gas signal detection. Three quality criteria are required for paleoclimate data series: (i) calibration and quantification, (ii) high resolution (seasonal to annual, sub-decadal), and (iii) scaling of amplitudes and to correctly assess the high- and low-frequency components of variability.This was precisely the target of the ongoing research project on lake sediments in Central Chile (NF 200021-107598; 2005-2008). During the past two years, we have made four major methodological innovations which are fundamental to produce such data sets from lake sediments: (i) high-precision chronologies of young lake sediments, which includes the SIT Sediment Isotope Tomography model, (ii) statistical tools from tree-ring research for calibrating lake sediments, (iii) exploration of new proxies and rapid high-resolution techniques (e.g., in-situ reflectance spectroscopy), and (iv) modification of the standard sampling protocol and flowchart of work. One of the latest results from that work is, for example a pigment-based (total chlorin) well calibrated (r=0.81; p<0.01; calibration period 1901-2000), quantitative (error of reconstruction = 0.24°C) high-resolution (2-3 years) austral summer DJF temperature reconstruction from Laguna Aculeo, Central Chile, back to the year AD 850. This data set is unique for the southern hemisphere and shows the great potential of in-situ reflectance spectroscopy as a novel tool for the rapid acquisition of high-resolution, quantitative climate proxies from lake sediments. The proposed research is the logic continuation and builds on the solid foundation of previous and current achievements by the research group in paleoclimate research in Chile. The proposed research follows two major thrusts (methodology and data):1. Methodology: Explore systematically the potential/limitations of in-situ reflectance spectroscopy as a novel tool for quantitative high-resolution climate reconstructions in a variety of lake types and sedimentary environments in south-central Chile, and2. Data: to produce a number of temperature and/or precipitation reconstructions from lake sediments (i) to shed light on the regional expression of climate variability during the past 1000 years, (ii) to contribute to the international regional multi-proxy climate reconstruction in South America (IGBP-PAGES LOTRED-SA, of which the applicant is the coordinator), and (iii) to assess the sensitivity of the global climate system to forced and unforced perturbations at a variety of temporal scales. Target sediment parameters with demonstrated skill are (i) relative absorption band depth RADB between 660-670 nm (indicative of total chlorin, highly correlated with Corg), (ii) reflectance R660nm/670 nm (indicative for chlorin diagenesis), (iii) RADB 610-620 nm and R570nm/R630nm (both indicative of lithic material), among others that need to be explored.The project will (i) systematically test the fundamentals of in-situ reflectance spectroscopy method for within-core, intra-site and intra-lake variability (3 x 3 cores in Lago Puyehue, Chile 40°S), (ii) cross-validate the reflectance spectroscopy data with ‘conventional proxies’ and calibrate the proxies with meteorological time series, and (iii) produce a quantitative regional composite climate reconstruction for the Lake District in Chile (38-42°S). The project contributes directly to international climate research programs (IGBP-PAGES / WCRP-CLIVAR).