A Review of Chesapeake Bay Climate Change: Potential Impacts on Watershed Hydrology and Nutrient and Sediment Cycling and Export

Climate change in the Chesapeake Bay watershed will affect the effort to achieve nutrient and sediment reductions called for in the total maximum daily load (TMDL) regulations. To determine how nutrient and sediment loads may change in response to climate, a systematic review evaluated research literature related to the impacts of climate change and variability on hydrologic fluxes and nutrient and sediment cycling and transport. Climate change impacts hydrologic fluxes, nutrient and sediment cycling, and export in the Chesapeake Bay region via several factors, including changes in precipitation volume and intensity, rising temperatures, and increased atmospheric carbon dioxide concentrations. Increased precipitation volume is expected to increase the water budget expressed via greater runoff, streamflow, and freshwater flows to the estuary, but seasonal changes, such as increased winter and spring precipitation and hotter, drier summers, increase the variability of these responses. Climate change will also alter the cycling and transport of nutrients and sediment, with higher temperatures increasing the rate of nutrient cycling, and increased precipitation, expressed as wetter soils, increasing losses. While there was considerable variability among studies, there was common ground that suggests the Chesapeake Bay watershed will experience greater nonpoint source nutrient and sediment loads. Ultimately, this information informs how climate change may impact efforts to meet the TMDL.