| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | August 18, 2014 |
| Latest Amendment Date: | August 18, 2014 |
| Award Number: | 1417886 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Anjuli Bamzai
OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | September 1, 2014 |
| End Date: | August 31, 2017 (Estimated) |
| Total Intended Award Amount: | $184,154.00 |
| Total Awarded Amount to Date: | $184,154.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
101 COMMONWEALTH AVE AMHERST MA US 01003-9252 (413)545-0698 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Amherst MA US 01003-9242 |
| 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): |
ARCSS-Arctic System Science, ANS-Arctic Natural Sciences |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
This project is aimed at understanding the response of the Greenland Ice Sheet to past climate changes, with the ultimate goal of improving predictions of its response to future change. The investigators will compile all available data on the size of the ice sheet at times in the past 20,000 years. They will also gather data on the history of surface air temperatures, the accumulation rate of ice, and surrounding ocean temperatures from ice- and sediment core records. The climate records will be used as inputs to a numerical model of the regional climate and the Greenland Ice Sheet to investigate the response of the ice sheet to changes in climate conditions. Direct observations of changes in the Greenland Ice Sheet only span the past few decades, making it difficult to identify a trend and distinguish it from natural variability. The relative roles of oceanic and atmospheric warming in driving Greenland Ice Sheet retreat also remain poorly constrained and debated. Ascertaining past Greenland Ice Sheet response to a warming climate can provide important bounds on the rates at which the ice sheet can retreat and lose mass. The last deglaciation (20 to 6 thousand years ago) provides a natural experiment for assessing large-scale Greenland Ice Sheet response to changing conditions including rising atmospheric carbon dioxide.
Three fundamental questions will be addressed by this project. 1) What drove the disparate behavior between west-east margins and southern margins of the ice sheet during the last deglaciation and how does this relate to abrupt deglacial climate change? 2) What is the relative importance of atmospheric versus oceanic warming in causing rapid ice margin retreat during the last deglaciation? 3) Given the large, sustained deglacial climate warming, what is the maximum rate that the Greenland Ice Sheet has delivered ice to the ocean as constrained by the geologic record and how do those rates compare with ice-sheet model simulations? Addressing these questions will 1) provide essential insight into how the broader Greenland Ice Sheet behaves in a warming world, 2) test the sensitivity of terrestrial versus marine ice-margin settings to warming, and 3) test the fidelity of a Greenland Ice Sheet model that can be applied to future simulations. The investigators will disseminate scientific results to the public through lectures and publications in popular science magazines, and to museums with movies and animations on the Magic Planet visualization system. The project will train a postdoc and Ph.D. student (geochronology-data analysis and numerical modeling) in a multi-disciplinary approach to paleoclimatology, glaciology, glacial geology, and paleoceanography. Undergraduates will work on the project, with a goal of recruiting under-represented groups in the geosciences.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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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 integrated new and existing surface exposure-age data from the Greenland margin with high resolution ice-sheet simulations, to determine the timing and primary mechanisms that drove retreat of different sectors of the Greenland Ice Sheet (GIS) through the last deglaciation. The project involved close collaboration between Oregon State University (data compilation, and proxy-based climate reconstructions), and the University of Massachusetts Amherst (numerical climate and ice sheet modeling). A new, proxy-based deglacial Greenland climatology was developed to drive our high-resolution ice sheet model (Buizert et al., in review), and to compare ice sheet simulations driven by the proxy-based climatology versus those driven by a coupled Regional Climate Model (Keisling et al, in prep). This required the adaption of the PSU/UMass ice sheet model and the RegCM atmospheric models to Greenland. Both of these tasks were accomplished by R. DeConto (UMass Amherst), and these model components are now being used for a wide range of past and future GIS simulations.
Key outcomes include the recognition of a clockwise trend in GIS retreat (beginning in the North) (Sinclair et al., 2016). Through detailed data-model comparisons of the timing of ice sheet retreat in 14 different regions (representing all the major ice-sheet drainages around the Greenland margin), we found that abrupt climate change during deglaciation (i.e. the Bølling warming and Younger Dryas) played an important role in the timing of retreat (Keisling et al., in prep). We also found that climate reconstructions that account for changes in seasonality throughout the last 21,000 years, yield a better match between measured and modelled timing of deglaciation for most regions (Buizert et al., in review; Keisling et al., in prep). Finally, we found that different sectors of the Greenland margin responded differently to atmospheric versus ocean warming during the deglaciation, which has important implications for understanding ongoing GIS mass loss, and Greenland’s potential future contribution to sea-level rise.
Outcomes of the project have been disseminated at national and international science conferences (AGU, EGU, PALSEA, IGS, among others), and in the primary, peer-reviewed literature. The new proxy-based Greenland climatology represents a major improvement over existing datasets, and we anticipate it will be used in the coming years by other ice sheet modelling groups studying the last deglaciation. Three new manuscripts are either in review (Buizert et al., in review) or are about to be submitted (Keisling et al., in prep). This work contributed to the education of graduate students at Oregon State University (Sinclair) and the University of Massachusetts Amherst (Keisling).
Last Modified: 01/04/2018
Modified by: Robert M Deconto
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