Long-term multi-proxy climate reconstructions and dynamics in South America (LOTRED-SA): State of the art and perspectives Preface

High-resolution, multi-proxy climate reconstructions with a representative spatial coverage over the globe are arguably among the most important tools for the assessment of the responses of the Earth climate to natural and anthropogenic forcing. Whereas hemispheric or regional multi-proxy reconstructions for the past 500-1000 years are available for Europe and North America, the Southern Hemisphere including South America has remained largely terra incognita. In this special issue we present a comprehensive review of previously published and new data sets from a variety of paleoclimate archives across southern South America (south of ca. 15 degrees S). The underlying collaborative research initiative started in 2006 under the umbrella of IGBP-PACES Focus 2 Regional Climate Dynamics and aimed to (i) collate the large number of disperse paleoclimate data sets from various proxies for the last ca. 1000 years, and (ii) produce a spatially explicit, highly resolved, multi-proxy climate reconstruction for southern South America. The review and research articles in this special issue cover a variety of archives (historical documents, tree rings, ice cores, glacier fluctuations and lacustrine sediments) and suggest that, at least south of ca. 18 degrees S, the spatial and temporal coverage of the data is adequate to develop synoptic multi-proxy reconstructions for the past ca. 400 years. Although additional high-quality proxy records are still needed to resolve the finer temporal and spatial structure of past climate variations, the currently available data do provide a consistent picture of climate fluctuations at a large scale. We have identified two major directions for future research: (i) a dedicated effort to build a comprehensive, quality-tested, and homogenized set of climate data during the (early) instrumental period in order to calibrate proxy data series, to test and extend reanalysis data sets, and to explore the multi-decadal variability of synoptic-scale atmospheric features, and (ii) expansion of the database of robust well-calibrated paleoclimate data series of adequate quality, temporal resolution and spatial representation; currently, this is the bottleneck for further improvements of the reconstructions. Existing older data sets should be updated to include the most recent years. While well-calibrated tree-ring archives and documentary data have restrictions in terms of spatial coverage and/or the length of the data series, calibration and quantification of proxy series from ice cores, glacier fluctuations, lake sediments and vegetation records are of utmost concern and require greatest attention. (C) 2009 Elsevier B.V. All rights reserved.