The field of paleoclimatology, and more generally the broader field of ``paleo-science,'' has seen substantial growth and increased recognition over the past decade. The prime motivation for these trends has been the need for a long-term, or ``paleo-perspective'' in understanding and assessing the environmental change that has been taking place and that will occur in the future. It is clear that climate varies substantially on all time scales, from seasons to millennia. It is also clear that the instrumental record of climate change is insufficient to observe and study how the climate system operates on time scales longer than a few decades, or under climatic forcing unlike that at present. The ``paleo-perspective'' afforded by clever use of the paleoclimatic, paleoceanographic, and paleoecologic records can be tapped to put the present and future into the broad context of many realizations of past climate system dynamics. This paper reviews many of the important advances that have taken place recently in the field of paleoclimatology in a context illustrating the key role paleoclimatology plays in narrowing the uncertainties associated with predicting future change in the climate system. The American Geophysical Union has requested that this review focus on progress made by the U.S. scientific community, however, many of the outstanding recent contributions in the field of paleoclimatology have been made by non-U.S. scientists.
In providing this update on the status of paleoclimatology, it is also illustrative to highlight the growing role paleoclimatology has come to play in the field of global change research over the last decade. The Intergovernmental Panel on Climate Change (IPCC) series of regular climate change assessments continues to draw more and more heavily on insights gained from the paleoclimatic record [ Houghton et al., 1992]. International coordination to provide these insights has led to the PAGES (Past Global Changes) Core Project of the International Geosphere Biosphere Programme (IGBP), paleoclimatic components of other IGBP Core Projects, paleoclimatic contributions to World Climate Research Programme (WCRP) activities, the international Paleoclimate Modelling Intercomparison Project (PMIP), and the establishment of the World Data Center for Paleoclimatology [ Webb et al., 1994]. Intensified paleoclimatic research activity within the US Global Change Research Program (USGCRP) is mirrored in many countries around the world. Paleoclimatology has clearly come of age as a major contributor to our understanding of how the Earth's climate system works.