Carbon saturation and weather in the coastal zone (C-saw): A workshop report

Weather or weather-influenced events—fires and storms—are altering carbon movement in the coastal zone: the “C-saw.” Sixty scientists gathered at North Carolina State University in October 2022 for an OCB scoping  workshop funded by NSF and NASA to push forward our knowledge of extreme weather on coastal carbon cycling. The workshop brought together a diverse community of monitors/observers, experimentalists, and modelers to address challenging knowledge gaps across the land-air-water spatial and temporal domains. We learned that both the spatial and temporal distribution of extreme weather is predicted to change as regions become wetter or drier. Also that carbon cycle responses were not always predictable but are strongly impacted by land use and antecedent conditions. Interactivity of different weather phenomena (e.g., drought or fire preceding extreme precipitation) can accelerate transfer of carbon and nutrients into receiving waters as much as interactivity of pulses of extreme weather events and more gradual presses of (e.g.,  sea level rise). This can result in loss of carbon stored in the landscape and its gain in receiving waters. These events may result in undersaturation in one domain and oversaturation in another over time scales that are poorly constrained.

Weather is thus a major driver affecting the build-up and rapid release and transformation of carbon at land-marine-atmosphere interfaces. The effects are most apparent in systems with long residence times that yield observable biogeochemical signals of  under- and oversaturation. Attendees articulated that sustained meteorological and biogeochemical observationsprovide key information on baseline properties of coastal systems that are critical for developing predictive models of system responses. In addition to characterizing the baseline, coordinated observing activities in response to extreme events must become commonplace to allow us to understand and identify coherent responses of coastal systems to gradients of extreme weather. To support and advance transdisciplinary C-saw research, participants discussed the establishment of sentinel sites in coastal regions that are heavily impacted by storms, tropical cyclones, and fires in order to support both baseline monitoring and responsive observations and process studies. Such sites could be strategically located to leverage established observing programs and resources.

Human communities strongly depend on coastal systems for food and economy. As these coastal systems continue to be threatened by more frequent and intense extreme weather events, it is imperative that we establish a collaborative interdisciplinary C-saw network to define the key observations, study criteria, and infrastructure needed to support research and decision making.

The workshop was recorded, and the recordings are available on the OCB YouTube Channel. After the workshop, a group of organizing committee members and workshop participants prepared a short summary of key priorities and recommendations to support research and monitoring efforts and grow a thriving C-saw community of practice, which was submitted to the U.S. Ocean Climate Action Plan request for input. Another workshop participant shared a summary of these priorities at COP-27. Additional workshop products planned for the coming year will include 1-2 papers describing the C-saw and how we should study it. Participants are also hoping to convene future workshops and community activities.