Quantifying the Blue Carbon Stock in Connecticut Long Island Sound Salt Marshes Grant Pace (NASA GISS Intern) Constraining uncertainty in the global carbon cycle depends greatly on both Blue Carbon and terrestrial carbon stocks. Coastal wetlands, potentially the most efficient carbon-burying ecosystems in the world per unit area, represent a key knowledge gap in both of these fields. However, coastal wetlands are increasingly at risk due to climate change, sea level rise, and anthropogenic disturbance and destruction. Despite the fact that salt marshes often sequester carbon several meters deep, nearly all estimates of salt marsh carbon stocks consider only the top 50cm or 1m. This presentation focuses on a calculation of full-depth carbon stock of Plum Bank Marsh, a Connecticut salt marsh in the Long Island Sound. These estimates use Dr. Peteet’s carbon content from sediment cores and probe depth data collected in 2019, using Python to apply and extrapolate this data onto and across the area of the marsh obtained from Landsat satellite imaging. Carbon density is then multiplied by the volume of the marsh to get the carbon stock (kg). This value is then compared to a simple calculation using average values as well as estimates using only the first 50cm and 1m to compare methodologies. In addition to calculating present-day estimates, future work aims to use earlier satellite imagery to calculate historical carbon stocks and carbon loss and to apply the same methodology to other Long Island Sound marshes, as well as Jamaica Bay, a New York City salt marsh heavily affected by anthropogenic disturbance and sea level rise that Dr. Peteet has collected data on since 2000. These findings have important implications for the global carbon cycle and the incorporation of Blue Carbon into global climate models, advocacy efforts aiming to conserve these marshes’ sequestered carbon, and the movement towards a more accurate standard of calculating Blue Carbon in salt marshes.