2014 Arctic

This project will further the understanding of ocean-ice-atmosphere interaction around the Jakobshavn Isbrae and Disko Bay region of west Greenland, with a particular focus on the role of sea surface temperature and sea ice variability in modulating past outlet glacier behavior and ice sheet/cap mass balance (snowfall and melt) over the past two centuries. The PIs will reconstruct past environmental conditions in the Disko and Baffin Bay region based on new glaciochemical and stratigraphic records from three 100-m deep ice cores, several firn cores, and geophysical studies from three sites surrounding Disko Bay.

This project will investigate the potential of carbon-14 in ice cores as an absolute dating tool, as a tracer of the past cosmic ray flux and as a recorder of the past fossil fraction of the global methane budget. Cosmic ray particles produce carbon-14 from oxygen-16 directly within near-surface glacial ice and firn. This in-situ produced carbon-14 quickly reacts to form 14C-containing carbon dioxide, carbon monoxide, and methane in the ice matrix. Some or all of the resulting 14C-bearing gases may be lost from the firn to the atmosphere. The proposed work will provide a thorough characterization of in-situ cosmogenic 14C in glacial firn and shallow ice in the Summit region of Greenland. It will examine the retention of cosmogenic 14C in ice grains at all depth levels in the firn column, the partitioning of 14C between carbon dioxide, carbon monoxide, and methane, as well as the production rates and accumulation of cosmogenic 14C in shallow ice below firn close-off.

The stable isotopic records from the Greenland Ice Sheet are the gold standard for understanding climate variations in the Arctic on decadal to millennial scales. While the basic tenets that underlie interpretation of isotopic information appear robust in a mean sense, meteorological and glaciological processes can confound simple interpretations. Processes of concern are variations in moisture sources, cloud processes, surface ablation, blowing snow and vapor diffusion in the firn. Continuous measurements of the isotopic composition of water vapor and daily measurements of the isotopic composition of freshly-fallen and blowing snow will be made at Summit (Greenland), Eureka (Ellesmere Island) and Reykjavik (Iceland). These will be combined with measurements of the amount, size distribution, and approximate habit of falling and blowing snow, turbulence measurements to evaluate snow lofting, surface latent heat flux (ablation and frost) and energy balance, and remote sensing of polar clouds and atmospheric structure. High-resolution firn cores will be drilled to reconcile the detailed isotopic measurements and modeling with glaciological records.

The aim of this collaborative project between investigators at three universities is to develop records of past climate in northwest (NW) Greenland and synthesize them with records of the position of ice margin to evaluate the response of the Greenland Ice Sheet to past warm periods. In support of the project, a 30-meter ice core outside of Thule Air Base in NW Greenland will be drilled.

This project involves the seasonal (winter) acquisition of cores from ice-covered northern (U.S. midwest) temperate lakes and rivers to investigate the spatial and temporal distribution of planktonic ice nucleating activity in fresh water ecosystems.