| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | September 12, 2011 |
| Latest Amendment Date: | July 1, 2013 |
| Award Number: | 1103380 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Paul Filmer
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | September 15, 2011 |
| End Date: | August 31, 2015 (Estimated) |
| Total Intended Award Amount: | $206,291.00 |
| Total Awarded Amount to Date: | $206,291.00 |
| Funds Obligated to Date: |
FY 2013 = $15,782.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
51 COLLEGE RD DURHAM NH US 03824-2620 (603)862-2172 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
51 COLLEGE RD DURHAM NH US 03824-2620 |
| 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: |
01001314DB NSF RESEARCH & RELATED ACTIVIT |
| 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
Technical description of the project
The main objectives of this project are to develop accurate and precise moraine ages in the Cordillera Vilcabamba of southern Peru, and to quantify the sensitivity of Holocene glaciers to climate changes, with the ultimate goal of elucidating Holocene climate variability and controls in the tropics. Initial work in the Vilcabamba has identified prominent glacial advances during the early Holocene and the 'Little Ice Age' interval, revealing a sequence of events that is broadly correlative with glacial records in Europe. These pilot results suggest climate teleconnections between the tropics and the North Atlantic region, but a more extensive array of data is needed to confidently identify regional glacial patterns and Holocene climate controls. This project will build substantially on initial findings by reconstructing glacial histories in additional valleys in the Vilcabamba using cosmogenic 10Be surface exposure dating of moraines, taking advantage of recent methodological advances that allow determination of extremely young (<200 year) and precise isotopic ages. Supplementing 14C ages and paleoclimate proxy data will be obtained from sediment cores recovered from bogs situated between 10Be-dated moraines. Independent 14C age control for these moraines offers the potential to develop a new local calibration of the 10Be production rate. The sensitivity of paleo-glacier mass balances to prescribed changes in specific climatic variables will be quantified by performing simulations with a glacier surface energy-mass balance model, thus allowing an estimation of the relative roles of major forcings such as temperature, precipitation, and solar radiation on glacier extent. Posited mechanisms of climate change will be assessed for their degree of consistency with the integrated age control and modeling results, enabling identification of likely drivers of Holocene glaciations and climate variability in the tropical Andes.
Broader significance and importance
The role of the tropics in triggering, amplifying, and transmitting global climate signals remains a topic of vigorous debate in climate science. Accurately dated records of past fluctuations in climatically sensitive tropical mountain glaciers are among the best indicators of regional trends in past climate changes and their causes. Peru harbors 71% of the world?s present-day tropical glaciers, and contains abundant geologic evidence of former glacier expansions. However, chronologies of past glacier fluctuations in this region are scarce, particularly during the Holocene epoch (the past ~11,700 years). New results from this project will contribute significantly toward an understanding of both the timing of Holocene glacier events in Peru and the predominant climatic influences on glaciation. Importantly, the new glacier chronologies will augment records of past climates developed from nearby ice core, lake, and marine sites as well as other emerging glacial histories, contributing to a more comprehensive characterization of regional climate changes and their environmental consequences. Results will thus allow for a rigorous examination of the underlying causes of tropical climate variability during the Holocene, including recent climate shifts relevant to understanding modern and future climate change.
An improved understanding of past Andean glaciations is crucial for predicting glacier responses to future climate change and consequences for local water resources, and for identifying environmental impacts on ancient civilizations in the region, including Inca and pre-Inca societies. This study will provide training in field techniques, laboratory methods, and numerical modeling for undergraduate and graduate students at the University of New Hampshire and Columbia University. The project will also expand on a productive collaboration between early career U.S. scientists and collaborators in Canada and Peru. Assembly of this multinational project team will enhance the development of research programs, facilities, and outreach activities at each participating institution. Research activities will also contribute to technique development by refining laboratory methods aimed at increasing the precision of widely used isotopic dating methods.
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.
The main objectives of this project were to develop a detailed history of late Pleistocene to Holocene glacial events in the Cordillera Vilcabamba of southern Peru, and to quantify the sensitivity of glaciers to climate changes, with the ultimate goal of identifying climate variability and controls in the tropics. Analyses obtained in this project provide new ages on moraine sequences in several glaciated valleys in the Cordillera Vilcabamba. We merged these new ages with previously obtained data to reconstruct a high-resolution composite chronology of glaciation. The glacial history is supplemented by radiocarbon ages from lake and bog sediments, which provide independent dating constraints that align with the isotopic ages of the moraines. The combined chronologies reveal the occurrence of several discrete glacial culminations in southern Peru. These glacial events are correlative with other dated moraine positions elsewhere in the tropical Andes and also correspond broadly with elements of glacial records in both the northern and southern hemispheres. To identify the dominant controls on tropical glacier mass balance, a suite of numerical models was applied to selected valleys in the Cordillera Vilcabamba. The valleys targeted for modeling contain present-day glaciers and preserve evidence for the areal extents and timing of past glacier fluctuations through precisely dated moraine sequences. Glacier sensitivity to specific climate parameters was tested by individually perturbing temperature and precipitation and comparing glacier length responses. These model simulations suggest that colder temperatures combined with enhanced precipitation are most likely to have supported past glaciers. Modeling outcomes further suggest that future warming will likely drive continued retreat of glaciers in this region of the tropics.
Last Modified: 11/30/2015
Modified by: Joseph M Licciardi
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