## Retrospective Analysis

Existing data sets need re-examination, and data sets that are particularly useful for examining past ocean conditions in relation to climate change, for example, paleoceanographic records, need to be developed. Data from fisheries have been collected for centuries, large hydrographic archives exist, and extensive specimen collections and data from environmental monitoring surveys are also available and need to be explored in an interdisciplinary climate context. Moreover, paleoecological data exists which extends fisheries, ecosystem and hydrographic data back in time beyond the limits of historical observation. Such data provide a window to the long time scale processes that characterize climate variability. A special property of the long historical records of fish, mammals and birds, is that they provide not only a history of the variation in population size, but also provide estimates of the life table variables (growth, mortality, maturity, and reproduction) that regulate population growth. It is these variables that respond directly to changing environmental conditions and must be linked to physical forcing which will enable forecasting of the effect of climate change on marine animal populations. The need for retrospective work is obvious when one considers that the five year duration of U.S. GLOBEC field programs corresponds to only 2-3 generations of most living marine resources (fish, benthic invertebrates) and perhaps 5-10 generations of most macrozooplankton, while climate change effects will be mediated over many generations. The U.S. GLOBEC program recognizes that retrospective data are indispensable for expanding the results of site-specific process studies to the larger scales that characterize the biogeographic distribution of populations and climate. Consequently, the identification, assembly and analysis of relevant existing data sets is important to achieving U.S. GLOBEC's goal of understanding the interrelationships of animal populations to ocean physics, climatic variability and long-term change.