Potential Impacts of Climate Change on Hood Canal Hypoxia

Abstract

Puget Sound can be found nestled in the northwestern corner of the United States. Puget Sound is the only home I have ever known. It is a place of expansive natural heritage with its evergreen forests, mountain ranges, rocky coastlines, rivers, and waterfalls. With this myriad of habitats, Puget Sound sustains thousands of wildlife species. However, the human impact is encroaching on the Sound and the natural processes that occur in the region. Over the past two centuries, human activities such as land clearance and fossil fuel burning have spurred an altered global climatic regime for the 21st century. Model forecasts suggest that global climate change will spur increases in ocean temperature and sea level as well as changes in freshwater flow magnitude and timing. Models also suggest that these changes in physical processes will impact biological processes. In particular, primary production in marine settings is expected to increase (Rabalais et al., 2009). This means that phytoplankton populations will expand, potentially leading to intensified hypoxia occurrences both in frequency and scope. Hood Canal is one of the multiple estuaries that comprise the Sound. I have chosen to focus exclusively on Hood Canal when available data exists because this region of the Sound experiences the most intense hypoxic conditions relative to the Sound’s other estuaries. Estuaries can be characterized as areas where fresh river flows meet ocean waters (Newton, 2003). Some data and information discussed is specific to Puget Sound as a whole rather than exclusively to Hood Canal. I include data and/or analyses specific to the broader context of Puget Sound since this is the existing data most closely related to Hood Canal when Hood Canalspecific data is unavailable and/or nonexistent. Additionally, an information gap exists in terms of the future Schandl 3 outlook of Hood Canal hypoxia. There is a lack of quantitative projections of the frequency and magnitude of Hood Canal hypoxia. Past and current studies have yet to synthesize how the factors that contribute to hypoxia will change in the face of climate change in order to concretely predict the trajectory of hypoxia in Hood Canal. In this paper, I synthesize some of the most critical factors that contribute to Hood Canal hypoxia, consider how these factors will be altered by climate change, and speculate what this will mean for the future of hypoxia in Hood Canal. The critical factors I examine are snowmelt timing and streamflow, ocean acidification, water temperature, salinity and density, and sea level.