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Information - CL024 Late Holocene climate swings - reconstructions, simulations, socioeconomic impacts
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Event Information |
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Rationale:
Within the IGBP-PAGES programme new initiatives are planned. For example, the detailed reconstruction and analysis of regional and global climate variability (mainly air temperature and precipitation) during the last few thousand years is essential. Mainly in central Europe one of the pressing issues is whether the last three warmer and partly drier climate optima during the last 4000 years (Bronze Age Optimum, Iron / Roman Age Optimum, Medieval Climate Optimum) were warmer than today or not. All three optima were folowed by a remarkable cold relapse: Iron Age Cooling, Migration Period Pessimum, Little Ice Age. Some colleagues do not like these expressions because the anomalies are neither spatially nor temporally homegeneous.
Based on reconstructed time series from important natural archives like glaciers, tree rings, pollen, lake levels, sea and lake sediments, stalagmites, boreholes and ice cores as well as documentary proxies the complex spatiotemporal pattern of temperature and precipitation fields is actually being analyzed in many regions of the world. In addition, first long-term model runs with coupled GCMs or models with intermediate complexity are carried out based on reconstructed forcings (sun, volcanoes, anthropogenic) and can be compared with the archive data. There is lively interest by many archeologists or archeoclimatologists for these topics.
Objectives of the session:
a) Evaluate the suitability of the different natural archives for the analysis of decadal to centennial scale climate variability during the late Holocene (last 4000-6000 years).
b) Define the characteristics of temperature and precipitation (or of combined proxy parameters) during the late Holocene climate optima and their following pessima.
c) Discuss suitable methods to compare reconstructed proxy time series with long-term model runs.
d) Estimate the contribution of the important forcing factors (sun, volcanoes) and of the internal climate variability to diagnose centennial scale climate variability during the late Holocene.
e) Detect and analyze possible interrelations between climate swings and reactions of the social and economic systems.
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