Site: Coweeta LTER

Predicting the impact of climatic changes on biota and ecological processes hinges on accurate projections of regional climate change. Researchers have already shown that there exists enormous variation in the manifestation of global climate change from region to region, with different areas of the globe experiencing widely varying shifts in climate patterns. Perched precariously in the middle of the rapidly growing Piedmont Megapolitan Region, the southern Appalachian region is characterized by high levels of endemic diversity and serves as a water tower for the widespread human development in the surrounding lowlands. Understanding how global climate change will manifest in this region and impact key ecosystem services of water quality, water quantity, and biodiversity will be critical to anticipating and preparing for impacts. Effective ecological impact research, though, is hampered by uncertainties surrounding regional manifestations of global changes.

Coweeta researchers examined eight decades of climate data available for the southern Appalachian region to assess the existence of any long term trends in climate and precipitation, to see if any such trends were linked to the North Atlantic Oscillation (NAO), and to see if changes in salamander abundance could be correlated with shifts in the NAO. The NAO is a recurrent teleconnection tied to relative atmospheric pressure differentials that influences weather in Europe and eastern North America. Though its impact on European ecology is well documented, its impact on North American ecology is relatively unknown.

By comparing annual climate measures across a series of weather stations in southern Appalachia, monthly NAO indices, and salamander abundance data, researchers showed a strong link between southern Appalachian temperatures and precipitation during the cool season and the NAO. Salamander abundance during the cool season was also found to be strongly correlated with the NAO. However, despite pronounced interannual variability in temperature and precipitation varying with the NAO, the researchers found no evidence of long term trends, suggesting that models that project rapid warming and drying by the end of the century may be inappropriate for use in southern Appalachia. Though the NAO seems to be a useful tool for predicting climate patterns in the region during the cool season, the lack of certainty regarding whether there will be reinforcement or weakening of this teleconnection means that researchers will have to consider multiple climate scenarios in order to capture the full range of possible ecological impacts in this region.

Graph for
Trends in southern Appalachian region (top) temperature and (bottom) precipitation by cool (left) (November- April) and warm (right) (May-October) seasons as measured by data collected at the Coweeta Hydrologic Laboratory since the 1930s.
Warren and Bradford 2010