1. DESCRIPTION OF THE WORKSHOP
1. DESCRIPTION OF THE WORKSHOP
2. INTRODUCTION
The impetus for this Workshop came from a growing need for long continental paleoclimate records within the Past Global Changes (PAGES) Project of the International Geosphere-Biosphere Programme (IGBP), together with the development of the International Continental Drilling Program (ICDP) and its Earth History and Climate Theme. In particular, the needs of the continental-scale, pole-equator-pole (PEP) transects of PAGES for long, high-resolution climate records provided a strong incentive for the Workshop.
Progress in global change research has come from many fronts in recent years. Much better understanding of the processes involved in the earth's climate system is now available, but along with this understanding has come a renewed awareness of the incredible complexity of the system. Much attention is deservedly given to climate-simulation models, most recently coupled ocean-atmosphere models, because of their ability to forecast. Such models, however, are just beginning to produce realistic simulations of human impact on the climate system that are comparable to those observed in the instrumental record (e.g. Santer et al., 1996). In addition to difficulties with accurately representing climatically important processes, models have problems in dealing with non-equilibrium conditions and non-linear responses. The record of the past shows that climate is constantly evolving, that "equilibrium" is relative to time scales, that sudden and unexpected events occur, and that earth systems may have internal, non-linear properties (such as "mode switches" in oceanic circulation). Thus, even as our understanding of climate processes grows, and our ability to model those processes increases, we are more dependent than ever on the record of past climate changes for true understanding of the climate system.
Finally, as important as it is to reconstruct climate changes of the past and to forecast them for the future, ultimately, it is the impact of those changes that are important to humanity. The continental paleoclimate record provides evidence of the impacts of past climate changes that are on a spatial and temporal scale that is relevant to human activity.
A wide variety of archives of continental paleoclimate records exist. These include historical records, tree rings, ice cores, relict geomorphic features, and sediments. The scope of the Workshop was restricted to records from sediment archives. Although records from all types of continental sediments are valuable and were considered within the scope of the Workshop, attention focused on lake sediments, because of their relative continuity, time resolution, and sensitivity to climate change, and because of the general ability to compare ancient lake sediments with their modern counterparts in the same lake. However, most of the discussion that follows applies to other continental sedimentary records as well, such as continuously accumulating loess in China.
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