| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | June 19, 2013 |
| Latest Amendment Date: | June 19, 2013 |
| Award Number: | 1343573 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
H. Richard Lane
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | April 1, 2013 |
| End Date: | April 30, 2014 (Estimated) |
| Total Intended Award Amount: | $129,505.00 |
| Total Awarded Amount to Date: | $129,505.00 |
| Funds Obligated to Date: |
FY 2012 = $74,883.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
1500 SW JEFFERSON AVE CORVALLIS OR US 97331-8655 (541)737-4933 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
104 CEOAS Administration Building Corvallis OR US 97331-8507 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Sedimentary Geo & Paleobiology |
| Primary Program Source: |
01001213DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Collaborative Research: Improved constraints on Holocene retreat history of the Laurentide and Scandinavian Ice Sheets from cosmogenic dating and implications for sea-level rise
Anders E. Carlson (U. of Wisconsin-Madison) EAR-0958872
Peter U. Clark (Oregon State U.) EAR-0958714
ABSTRACT
A major objective of ice sheet and climate research is to understand the responses of ice sheets to climate change. Ascertaining the past rates of ice-sheet retreat and contributions to sea-level rise under climate that was naturally warmer than present provides context for the future Greenland Ice-Sheet response to global warming. Here, this research team proposes to improve the deglacial chronologies and investigate retreat rates of the Laurentide (LIS) and Scandinavian (SIS) Ice Sheets during the early to mid-Holocene (<11.7 ka), a period of time that provides an excellent natural experiment where these terrestrial ice sheets deglaciated under a climate warmer than present but potentially similar to the end of this century. This project proposes to directly date the retreat of the southeastern and eastern LIS margins and the southern, eastern, and northern SIS margins during the early to mid-Holocene using in situ cosmogenic surface exposure ages, significantly improving the chronology for the largest of the LIS domes and the majority of the SIS. The resulting chronologies will be combined with already existing cosmogenic chronologies from western Quebec, northeastern Labrador and southern Finland, and existing minimum limiting radiocarbon dates and varve records. These data will allow calculations of LIS and SIS retreat rates and sea-level rise contributions during the early to mid-Holocene, with the remainder of sea-level rise largely attributable to the Antarctic Ice Sheet. The results will provide estimates of the natural rates at which ice sheets can melt under radiative forcing that may be analogous to the climate of the end of this century.
Broader Impacts
Given that the greatest uncertainty in predicting future sea-level rise in response to global warming are the contributions from the remaining ice sheets, it is critical to constrain melt rates under warmer than present climates. Results of this research will provide climate scientists with estimates of the retreat rates and attendant sea-level rise contributions from terrestrial ice sheets under a climate naturally warmer than present. The information gained from this research will be of significant importance for policy decisions and of interest to a broad range of earth scientists and the public in general. This research proposal will support 2 Ph.D. students who will be exposed to a multi-disciplinary scientific approach that includes paleoclimatology, glacial geology, cosmogenic isotope geochemistry and paleoceanography. It will also provide support for an untenured, early career Assistant Professor furthering his academic career.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This project investigated the timing of Laurentide Ice Sheet (LIS) margin retreat in Quebec and Labrador, Canada – the Labrador Dome. The goal was to determine how fast LIS margins can retreat under a climate forcing similar to what is expected by the end of this century. To do this, we sampled boulders left by the LIS on the Canadian Shield along 3 transects across eastern Canada. We measured the cosmogenic nuclide 10-Be in these samples to date the timing of ice retreat. This technique determines how long a rock has been exposed to cosmic ray bombardment since it was left by ice. We produced in total 68 dates from multiple sites eastern Canada (see Figure).
We found the western Labrador Dome retreated very rapidly just prior to ~7,900 years ago, or basically collapsed along its 600 km extent. In contrast, the southern and eastern Labrador Dome retreated slower. We attribute the different retreat rates to variations in precipitation, with the southern and eastern ice margins receiving more snow than the drier western margin. We estimate that the Labrador Dome collapse raised sea level 2-3 m in a few centuries. The accuracy of our new dates also shows that this collapse may have slowed the North Atlantic current and caused a century-long cold event.
We are going to compare this chronology with a new chronology for the Scandinavian Ice Sheet being developed by collaborator Dr. Peter Clark.
The broader impacts of the award were the support of Dr. David Ullman’s PhD, and Professor A. Carlson’s tenure track. Publications are still in preparation, but Carlson published two review papers (Nature Geoscience, Reviews of Geophysics) while supported by this award. Seven presentations were made at international meetings.
Last Modified: 05/02/2014
Modified by: Anders E Carlson
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