Along active margins with narrow shelves, such as the North American Pacific Coast, a larger region than just the shelf needs to be considered to meaningfully discuss coastal carbon dynamics. Along passive margins with broad shelves like the North American Atlantic Coast, the continental shelf is the relevant spatial unit for discussing carbon fluxes.
Although the two definitions overlap, there are important reasons for considering both. Two different terms will be used here when referring to ocean margins: 1) the coastal ocean, defined in this report as nonestuarine waters within 200 nautical miles (370 km) of the coast, and 2) continental shelves, which refer to the submerged margins of the continental plates, operationally defined here as regions with water depths shallower than 200 m (indicated in gray in Figure 16.1). The second is directly relevant to coastal ecosystem health, fisheries, and aquaculture. The first is relevant to overall quantification of the ocean’s uptake of CO 2.
#Continental shelf drivers
This chapter focuses on two particularly pressing issues within the much broader topic of carbon cycling along ocean margins: 1) the uptake of atmospheric CO 2 and subsequent export to the deep ocean and 2) patterns and drivers of coastal ocean acidification. The collective impact of these factors on carbon processing and exchanges along ocean margins is complex and difficult to quantify (Regnier et al., 2013). The drivers underlying these trends include rising atmospheric carbon dioxide (CO 2) levels, climate-driven changes in atmospheric forcing (e.g., winds and heat fluxes) and the hydrological cycle (e.g., freshwater input from rivers), and changes in riverine and atmospheric nutrient inputs from agricultural activities and fossil fuel burning. Anthropogenic activities lead to secular trends in these exchanges. Zhaohui Aleck Wang, Woods Hole Oceanographic InstitutionĪlong ocean margins, the atmospheric, terrestrial, sedimentary, and deep-ocean carbon reservoirs meet, resulting in quantitatively significant carbon exchanges. Nadja Steiner, Fisheries and Oceans Canada Samantha Siedlecki, University of Connecticut Lisa Robbins, University of South FloridaĮlizabeth H. Najjar, The Pennsylvania State University Lohrenz, University of Massachusetts, Dartmouthįrank Muller-Karger, University of South Florida Xinping Hu, Texas A&M University, Corpus Christi Jose Martin Hernandez-Ayon, Autonomous University of Baja California Feely, NOAA Pacific Marine Environmental Laboratory John Dunne, NOAA Geophysical Fluid Dynamics Laboratory Leticia Barbero, NOAA Atlantic Oceanographic and Meteorological Laboratory Alin, NOAA Pacific Marine Environmental Laboratory Lead Author: Katja Fennel, Dalhousie UniversityĬontributing Authors: Simone R.
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