Home >Introduction Climate Variability Impacts on Ecosys. Degradation & Restoration in Chesapeake Bay Baseline Variability: Chesapeake Bay Chesapeake Bay WQ & Climate Variability FL Everglades: Hydro. Changes & Degradation Everglades Climate Variability & Relevance Role of Time in Restoration Planning Acknowledgements References Figures

Paleoecology - the study of ecosystem history over various timescales using sedimentary records - provides a unique temporal perspective on patterns, causes and rates of ecological change due to natural hydrologic and climatic variability and anthropogenic activity. Traditionally, paleoecological records, coupled with instrumental records of various length and quality, have provided firm evidence about the timing and scope of the negative impacts from human activities such as fertilizer application and nutrient loading (Brush 1984; Cooper and Brush 1991). More recently, paleoecological studies have begun to have a much greater influence than simply documenting trends in ecosystem degradation. First, they provide specific information on pre-anthropogenic baseline levels of variability in biological (community structure, diversity), physical (salinity, turbidity) and chemical (dissolved oxygen) parameters now used to set scientifically rigorous restoration targets for impaired ecosystems (Jackson et al., 2001; U.S. EPA, 2003). Environmental reconstructions use not only fossil assemblage data, but include geochemical proxies for aquatic or atmospheric conditions, allowing direct comparison of biological and physical patterns.

Second, paleoecological research has provided definitive evidence that interannual to multi-decadal temporal variability in both terrestrial and aquatic ecosystems is caused by natural climatic processes such as El Niño -Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO). Climate variability can be significant, even in comparison to more regional environmental stressors, and should be incorporated into ecosystem management (Harris et al., 2006; Cronin and Walker, 2006). The emergence of climate as a driving force for ecosystem management is even more in evidence in the findings of the Intergovernmental Panel on Climate Change (IPCC, 2007). The IPCC has concluded that human-induced climate change has already had several impacts: earlier timing of spring events (leaf-unfolding, bird migration and egg-laying), poleward and upward (elevation) shifts in ranges in plant and animal species, altered ranges of algal, plankton, and fish abundance in high-latitude oceans, and range changes and earlier migrations of fish in rivers. Although much greater uncertainty surrounds future climate change and ecosystem response, the combined effects of changes associated with climate change (e.g., flooding, drought, wildfire) and anthropogenic drivers of climate change (e.g., land use change, pollution, over-exploitation of resources) are likely to overwhelm the resilience of many ecosystems in the next century (IPCC, 2007).

Third, many ecosystem restoration and management programs rely heavily on modeling to forecast ecosystem response to various management options. Paleoecological data are now used in conjunction with model development to calibrate climate models used to analyze the dynamics between human activity and regional climate and establish baseline targets for water quality and quantity (Marshall et al., 2004; Marshall et al., 2006; U.S. EPA, 2003). This paper summarizes the contributions of paleoecological and paleoclimatic reconstructions to restoration planning for two premier ecosystems in the eastern United States: Chesapeake Bay, the largest estuary in the nation, and the Florida Everglades, the largest freshwater wetland in the nation.