Collaborative Research: Reconstruction of Carbon Monoxide in the Pre-Industrial Arctic Atmosphere from Ice Cores at Summit, Greenland

The main goal of this work is to provide the first reliable record of pre-industrial carbon monoxide (CO) concentration and stable isotope composition in the Arctic atmosphere, which will also be representative of a large part of the Northern Hemisphere. Carbon monoxide concentrations are a crucial component of any complete modern or past atmospheric data set because CO plays a key role in global atmospheric chemistry by being the largest single sink of hydroxyl radicals in the lower atmosphere. Carbon monoxide concentration in combination with stable isotopes is also a powerful tracer for large-scale biomass burning variations. Pre-industrial carbon monoxide concentration in the northern hemisphere (where anthropogenic impacts have been by far the strongest) is poorly characterized, with prior measurements made using an older technique in the 1990s on only a few samples from one ice core. No published carbon monoxide isotope measurements from northern hemisphere ice cores are currently available. Researchers on this project will collect a new large diameter ice core near Summit, Greenland using the Blue Ice Drill (BID), providing ice from 80 to 170 meters depth (air age from about 1960 to about 1600 AD). Continuous measurements of carbon monoxide concentration will provide a high-resolution record over the entire ice core and identify ice layers where carbon monoxide is well preserved. High-precision discrete analyses of carbon monoxide concentration and isotopic composition will then target ice from these layers. Continuous analyses of trace chemistry and discrete analyses of trace organics will also be conducted to establish the ice core chronology and improve understanding of mechanisms of in situ carbon monoxide production in ice. Atmospheric histories for carbon monoxide concentration and isotopic composition will be derived using a combination of firn-ice gas transport and inverse models, and the implications for pre-industrial carbon monoxide budget will be investigated with the use of a climate-chemistry model. This approach maximizes the chance of obtaining a reliable history of carbon monoxide concentration and isotopic composition through careful site selection and the application of novel ice drilling and analytical techniques. Results from the study will be made available to the scientific community and the general public through the NSIDC and NOAA Paleoclimatology data centers. The work will contribute to the training of two graduate and 2 undergraduate students, support an early career investigator, and establish several new collaborations among the investigators.