Hydrochemical response of high elevation watersheds to climate change
Global climate change is emerging as the single most important environmental issue of the 21st century. The direct and indirect effects of climate change on terrestrial and aquatic ecosystems are highly complex and poorly understood. High elevation watersheds can be a useful unit for studying climate-induced effects because they are sensitive to global change processes and may serve as a bellwether for more resistant ecosystems of higher order watersheds. These watersheds are characterized by shallow soils that are poorly buffered, making them responsive to small, but measurable changes in energy, water and chemical inputs. Furthermore, by studying these more remote ecosystems, it is possible to minimize the complexity associated with urban influences and land cover change, enabling more specific focus on the effects of climate change. Many LTER sites collect long-term data from small, undisturbed watersheds, providing quantitative measurements of chemical and hydrologic fluxes. These data are well-suited for examining past responses to climate and for evaluating biogeochemical models used for projecting future responses. Biogoechemical models are becoming increasingly more sophisticated and provide a practical approach to investigating the interactive effects of future changes in climate with other drivers of global change (e.g., atmospheric deposition, CO2). Historically, modeling efforts were limited by the availability of climate input data, which consisted of coarse resolution climate projections from atmosphere-ocean general circulation models (AOGCMs). Data from AOGCMs are suitable for global analyses, but not local applications, particularly in mountainous regions where there are large ranges in climate over small spatial scales due to heterogeneous topography. The advent of new techniques that employ statistical and dynamic downscaling make it possible to simulate biogeochemical responses to climate change at individual sites. Confidence in these recent climate projections is much greater than for past projections, providing a sound basis for examining climate effects in small, high-elevation watersheds. The goals of this workshop are to (1) design a cross site initiative to assess changes in climate and associated hydrochemical responses of mountainous watersheds, and (2) explore how statistically downscaled AOGCM data can be coupled with watershed hydrochemical models to make projections about future changes in hydrology, biogeochemical cycling and water quality in these watersheds.