Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)
DESCRIPTION:
The GRate project is funded by the National Science Foundation and led by Jason Briner @ University at Buffalo in collaboration with a team of science experts from multiple disciplines and academic institutions. The project grew from the earlier "Snow on Ice" initiative that focused on the fluctuations of the Greenland ice sheet throughout the holocene, focusing on SW Greenland. GRate will expand that work, further exploring Greenland's ice sheet stability through the linked systems of ocean, ice and atmospheric conditions using paleoclimate proxies and infusing these into an updated Greenland wide ice sheet model.
Reconstructing Greenland’s Ice Margin is done through radiocarbon dating sediment samples cored from pro-glacial lakes (lakes created along the ice sheet margin from glacial meltwater) to track ice sheet retreat and expansion. Quartz rock samples are collected for cosmogenic nuclide analysis from both free standing glacial erratics and rows of rocky moraines deposited along the ice sheet margin. Paired analysis of a suite of different isotopes (14C, 10Be, 26Al and 36Cl) are used to reconstruct the history of the ice sheet margin over the past 20,000 years. Both sediment and rock samples are used to constrain Greenland’s minimal Holocene ice edge. (Jason P. Briner, U@B, PI, Nicolás Young, LDEO, PI, Joerg Schaefer, LDEO, PI)
Image: Quartz sample are collected from a glacial erratic deposited on the landscape as the ice sheet retreated for paired radioactive isotope analysis. The surface exposure dating is correlated with the ages from the lake sediment cores, applying a second independent method of dating Greenland’s ice sheet extent.
Hydroclimate data is calculated from hydrogen isotopes extracted from the water in lake sediment cores and leaf waxes from local plant cover using stable hydrocarbon chains. Precipitation isotopes reflect moisture sources, with lake water isotopes reflecting seasonality through their inflow and evaporation. Thousands of years after the leaf waxes are blown into the lake their hydrocarbon chains remain unchanged and can be used as a proxy for paleoclimate.(Elizabeth Thomas, U@B, PI)
Image: Samples prepared and ready to be run through the isotope ratio mass spectrometer to establish a hydrogen isotope ratio. In the lab solvent is pumped through the mud to release the waxes, the sample is then purified and analyzed for the hydrogen isotopes of the leaf waxes. These are used to reconstruction a picture of paleo-climate temperature and moisture balance in the Holocene. (photo D.Levere University at Buffalo)
Arctic dinocysts assemblages are analyzed as a proxy for sea ice cover along Greenland's coast. Dinocysts are dormant zygotes of dinoflagellates, small plankton, that in the Arctic can be used as paleoclimate markers of past sea ice cover, water temperature and salinity. Through collecting ocean sediment cores in targeted areas along the Greenland coast the dynocyst assemblages can provide temperature and ice data for the area. (Anne de Vernal, GEOTOP Montreal, PI)
Greenland Ice Core and Pollen Data extended through the Holocene is used to reconstruct the surface temperature and ice accumulation. Large proxy data assemblages have been used to provide to provide boundary conditions tol guide the ice sheet modelers. (Greg Hakim, U Washington, PI, Eric Steig, U Washington, PI)
Modeling efforts will continue to integrate observational ice surface data and improved Greenland bed topography data into both expanded regional models and the Greenland-wide Ice Sheet System Model (ISSM) to continue to move this powerful model into more recent Geologic history. The models developed in our prior ARCSS project, Snow on Ice, focused on the SW geographic region of Greenland over the last 8000 years in the Holocene. The GRate project will expand the modeling to look at change across the broader Greenland Ice Sheet over this same period. (Jesse Johnson, Montana, PI, Mathieu Morlighem, Dartmouth, PI, Eric Larour, JPL, PI, Josh Cuzzone, JPL, PI)
Education & Outreach efforts are focused on building diverse pathways into the Geosciences. We created a set of science trading cards that focused on our Early Career Scientists and bringing them to life as 'superheroes' with cool tools that enabled the super powers they use to uncover new scientific insights. Created by scientist and artist Jeremy Stock, these incredible superheroes together focus on ‘system science’ as they uncover new findings about past climate, that when matched to the present help us build models about the future. Educators will find out NGSS aligned instructional materials that address the question ‘How do we know about the past?’ as they explore the use of ‘science proxies’. Each superhero scientist has a set of activities and supports that help you bring their science story to life in the classroom in an engaging and personal way!
Image: An example of Science Superhero cards of some of our amazing scientists. Full sets of Middle School and High School curriculum that explore "How do we know about the past?" can be downloaded.
For this early part of the season the goal is to tease apart a record of historic precipitation and temperature for this region using isotopes from leaf waxes collected in the lake sediments.
Superheroes are identified by their unique powers and skills, allowing them to see and act in ways that inspire awe in the rest of us. Do scientists have superhero powers?
We awoke to messages that a towering iceberg is threatening the local waterfront settlement of Innaarsuit. There is perhaps a bit of irony in the fact that a massive looming block of ice is a potential threat to the start of our field season.
Snow on Ice is launching into the field with two teams of scientists this summer. The first group, an ‘advance team’ of six women, will focus on lakes where meltwater has collected on the southwestern flank of Greenland bedrock.
Scientists are collecting lake sediment, rock, water and plant samples to tease apart linkages between Arctic sea ice, atmospheric uptake, and changes in snowfall on the Greenland Ice Sheet.
Testing the Slab Connection: A 10Be and 10Be/9Be Tracer Study in the Transmexican Volcanic Belt