| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | September 21, 2010 |
| Latest Amendment Date: | September 21, 2010 |
| Award Number: | 1003471 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Paul Filmer
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | October 1, 2010 |
| End Date: | September 30, 2014 (Estimated) |
| Total Intended Award Amount: | $217,013.00 |
| Total Awarded Amount to Date: | $217,013.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
5717 CORBETT HALL ORONO ME US 04469-5717 (207)581-1484 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
5717 CORBETT HALL ORONO ME US 04469-5717 |
| 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): | GLOBAL CHANGE |
| 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): | 47.050 |
ABSTRACT
The role of the tropics in climate change has important implications for understanding both orbital-scale and abrupt climate variations. Yet our ability to assess tropical behavior during major climate events, such as the last glacial maximum (LGM), is limited by poor spatial coverage and insufficient control on sample ages. This project will address this problem by developing well-dated records of glacial fluctuations from the LGM through the termination and late-glacial period at Nevados Coropuna and Allinccapac in southern Peru and use these data in numerical simulations of glacier mass balance and local climate. These sites allow an examination of glacier variations, as well as coeval snowline changes, along a transect from the arid (Coropuna) to the humid (Allinccapac) Andes and thus document how major climate events may have been expressed in areas with distinctly different environments. This work consists of detailed mapping of moraines; precise surface-exposure age dating (3He and 10Be) of carefully selected boulders from moraine crests and drift edges; basal 14C ages of bogs interspersed among moraines; calculation of former snowline depression; and modeling of the relationship between glacier mass-balance changes and climate. The work will be an important step towards understanding tropical behavior and will finally allow a thorough testing of the Milankovitch hypothesis of ice ages in the tropics.
Broader Impacts: This research educates and trains students, a postdoc, and a recent female Ph.D. There is a lecture series on local geology and global climate change given to eco-tourism students at the University of Arequipa, as well as lectures to the Lima archaeology department. K-12 students benefit through a long-standing associations with classrooms in rural, commonly economically disadvantaged Maine. The project maintains a website and is exploring a learning module. In addition, the research is part of a joint initiative to understand land use and settlement patterns of the first Americans in the Peruvian highlands.
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 investigation has sought to reconstruct the timing and the magnitude of key tropical climate events during the last glacial-interglacial transition, in order to assess the tropical response to ice-age forcing and, thus, how the tropics relate to global change. Employing Andean glaciers as palaeothermometers, we mapped glacial deposits in two very different parts of the Peruvian Andes - the arid Western Cordillera and humid Eastern Cordillera - and dated these deposits using cosmogenic 3He and 10Be surface-exposure methods. Subsequently, we reconstructed palaeo-snowlines to quantify the degree and rate of climate warming in the high Andes at the end of the ice age.
Our data show that, despite contrasting environmental conditions, both regions responded in a uniform manner to late Quaternary climate variability. Moreover, far from being regionally disparate, the last glacial maximum in the southern tropics was synchronous with global events and was of a similar magnitude, despite the relatively minor influence of insolation variability at these latitudes. Additionally, our chronology indicates that the transition from full ice age to interglacial in the tropics was not smooth but was interrupted by two short-lived periods of renewed cooling, suggesting that the tropics are every bit as capable of abrupt climate fluctuations as higher latitudes. Together, these findings suggest a potentially fundamental role for greenhouse gases and/or tropical ocean temperatures in driving global climate on both ice-age and abrupt timescales. Finally, over the course of the investigation we have refined the 3He surface-exposure dating method, implementing an acid-cleaning step that improves sample purity considerably.
Our work helps to inform modern studies on glacier extent and meltwater variability - a concern in Peru, where a significant percentage of hydropower and irrigation relies on glacial melt. Other broader impacts of our work include the development of collaborations with Peruvian scientists and NGO agencies and the education of students of all ages, from K-12 to senior college.
Last Modified: 10/27/2014
Modified by: Brenda L Hall
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