Multi-decadal year-round CO2 and CH4 fluxes to understand long-term impact of climate change on the Arctic carbon balance

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Organic carbon in northern soils is more than double the current atmospheric pool. An increasing fraction of this organic carbon is vulnerable to conversion to carbon dioxide (CO2) and methane (CH4). However, there are still large uncertainties in the potential rates of carbon loss from the Arctic with climate change because of the sparse spatial and year-around data from Arctic ecosystems. Temperatures in far northern latitudes have increased by 0.6 °C in the last 30 years, which is twice the global average with the largest increase in the non-summer seasons. This increase has been linked to increased atmospheric concentration of greenhouse gas (GHG) fluxes in high latitude wetlands but the drivers of this renewed growth are still largely uncertain. It is impossible to predict or attribute changes in atmospheric greenhouse gas concentration to increased carbon loss from Arctic ecosystems without a long-term record from tundra ecosystems. Particularly unknown is the response of cold season carbon loss from the Arctic, given the sparse data available outside of the summer period. This project will generate the long-term continuous data critical to identify temporal changes in GHG balance from the Arctic and will attempt to identify how changing cold season climatic conditions may alter annual Arctic greenhouse gas release to the atmosphere. This knowledge is required to inform current and future models and help ensure rigorous predictions of future GHG emissions from the Arctic. This project will support continued engagement of under-represented students in the Arctic. The project will conduct outreach at the local middle and high schools in Utqiagvik, Alaska, and will continue to collaborate with Ilisagvik College to involve the local students into research activities.This project establishes long-term, year-round field observations to better understand the controls on greenhouse gas (GHG) emissions from the Arctic at time scales that will encompass climate change and variability. This project will allow creating the longest running year-round Arctic eddy covariance network, and to standardize, upgrade, and apply the network to improve understanding of the long-term effects of climate variability and change on trace gas feedbacks from the Arctic. This project will make existing data more useful and will expand an already large user base. A special emphasis will be on the fall zero curtain period when an unfrozen soil layer hovers around 0°C supporting significant CO2 and CH4 releases to the atmosphere. Zero curtain processes plausibly explain how upland tundra can be a larger emitter of CH4 than low-lying, wet tundra, and how the cold seasons might emit more CH4 than the summer. Five Arctic eddy covariance flux towers will be used to evaluate the long-term changes in the CO2 and CH4 fluxes across three moisture environments in Utqiagvik and a ~300km latitudinal gradient passing through Atqasuk and Ivotuk. These measurements are intended to be of sufficient duration and breadth to capture and interpret the effect of extreme and/or unexpected events on GHG fluxes in the Arctic. This project will allow expansion of the time-series to a more than 20-year record of CO2 and 11-year record of CH4 fluxes, resulting in an unprecedented dataset critical to refining our analytical and predictive ability of the controls of CH4 loss from the Arctic.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.