Ocean acidification in the western Arctic Ocean

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Rising carbon dioxide concentrations in the atmosphere, global climate change, and the sustainability of the Earth's biosphere are of great societal concern. This is true in the Arctic Ocean as it is widely viewed as one of the most sensitive regions on Earth to climate change. Understanding the carbon cycle and its underlying control mechanisms is necessary to predict how carbon flux in the Arctic Ocean will change, as well as feedbacks to the larger climate system. This project will measure components of the carbonate system to understand ocean acidification in the western Arctic Ocean through collaboration with the Chinese National Arctic Research Expedition (CHINARE) cruises along a transect from the Bering Strait to high latitude basins. The investigator will collect high resolution inorganic carbon data during summer 2020. These data, supplemented by a subset of data collected in 2019 and 2021 by CHINARE collaborators, will be used to understand the mechanisms controlling carbon cycle and fluxes and ocean acidification in the western Arctic Ocean and the changes that have occurred in recent decades. Continued data collection and data synthesis are important to understand major environmental and climate-related changes in the marine carbonate system in the Arctic Ocean. This research will enhance the infrastructure of ocean carbon research and general science education through teaching undergraduate and graduate courses at the University of Delaware. In addition, it will enhance international collaboration and public awareness of climate change and environmental issues through public outreach activities. Observing and understanding the mechanisms controlling the carbon cycle in the Arctic Ocean is necessary to predict future conditions and feedbacks to climate change. This study will test the hypothesis that high biological production and low partial pressure of carbon dioxide (pCO2) are limited to the Chukchi shelf and the sea-ice melt edge and that ice-free basin areas are characterized by high pCO2, low pH, and low carbonate saturation state. A comparison of the new data with those collected between 2008 and 2018 during CHINARE, as well as other historical data, will be used to test the hypothesis that the expansion of the basin area to north characterized by increasingly higher pCO2 and lower pH is due to the earlier timing and longer summer warming, reduced buffer capacity, and increased pCO2 in the atmosphere. Finally, water column data collected in 2020 together with earlier data will be used to test the hypothesis that the expansion of ocean acidification from subsurface to deeper depths and to higher latitudes is primarily caused by the increased input of the Pacific Winter Water into the subsurface basin driven by rapid environment change such as sea-ice retreat.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.