Surface Mass Balance of the Greenland Ice Sheet
This research aims to quantify changes in snowfall, temperature, snow density, surface melt, and snow reflectivity (albedo) across the Greenland Ice Sheet, to better understand how modern climate change is affecting Greenland mass balance (how fast is it melting?) and global sea-level rise. These projects provide valuable field data needed to validate climate models used to predict future melting of the ice sheet with continued warming. Our latest project is called “GreenTrACS” (Greenland Traverse for Accumulation and Climate Studies), and includes 1000+ km snowmobile traverses across western Greenland in 2016 and again in 2017 (see figure). Along the traverses we are collecting snow/ice radar data showing annual snowfall layers, high-precision surface elevation data to track the lowering of the ice sheet, snow reflectivity data to see how pollution and warming are darkening the ice sheet surface, and a series of 16 ice cores to track snowfall and snow melting over the past 40-50 years. Follow our blog, and check out the youtube video about this project.
Publications: Lewis et al., 2021; Meehan et al., 2020; Lewis et al., 2019; Lewis et al., 2017; Osterberg et al., 2015; Hawley et al., 2014; Wong et al., 2013
The South Pole Ice (SPICE) Core and Upstream Dynamics
We are analyzing the new SPICEcore at high resolution for major ion and trace element chemistry to explore the signature and causes of natural climate change in the region surrounding Antarctica over the last 40,000 years. This is a period when the Earth transitioned from an ice age into the modern warm period. We are investigating how the wind belts that surround Antarctica changed in their strength and position through time, and documenting explosive volcanic eruptions and CO2 cycling in the Southern Ocean as potential climate forcing mechanisms over this interval. Understanding how and why the climate varied naturally in the past is critical for improving our understanding of modern climate change and projections of future climate under higher levels of atmospheric CO2. Our data are also be essential for developing the ice core timescale that will be used by all SPICEcore researchers. We are also investigating the ice upstream of the SPICEcore drill site to assess ice flow conditions, spatial patterns in snow accumulation, and firn compaction, all critical to the proper interpretation of the ice core.
Publications: Winski et al., 2021; Epifiano et al., 2020; Winski et al., 2019; Hartman et al., 2019
Response of the NW Greenland Ice Sheet to Holocene Climate Change
The aim of this collaborative project between researchers at Dartmouth, Northwestern and UMaine is to develop records of past climate in northwest (NW) Greenland and synthesize them with records of the ice margin position to evaluate the response of the Greenland Ice Sheet to past warm periods, such as the Holocene Climatic Optimum (approximately 5 to 9 thousand years ago). The proposed research integrates multiple climate proxies collected from the Thule region with glaciological modeling experiments to address the following research objectives: (1) reconstruct Holocene climate in NW Greenland via inferences from reconstructed local ice cap extents (North Ice Cap, Tuto Ice Cap), ice core stable isotope and precipitation records, and data from nearby lake sediments; (2) Examine the sensitivity of the NW Greenland Ice Sheet (GIS) to Holocene climate changes by developing the history of the areal extent of the GIS and synthesizing proxy data with glaciological modeling experiments to examine past GIS changes and predict future GIS retreat. Results from this project will enable a more accurate prediction of the NW Greenland cryospheric response to a future warmer world and provide information directly relevant to predictions of future sea-level rise.
Publications: Axford et al., 2019; McFarlin et al., 2018; Lasher et al., 2017; Osterberg et al., 2015; Wong et al., 2015