
NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
Recipient: |
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Initial Amendment Date: | February 26, 2018 |
Latest Amendment Date: | March 6, 2020 |
Award Number: | 1702789 |
Award Instrument: | Continuing Grant |
Program Manager: |
David Verardo
AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
Start Date: | March 1, 2018 |
End Date: | February 28, 2023 (Estimated) |
Total Intended Award Amount: | $544,853.00 |
Total Awarded Amount to Date: | $544,853.00 |
Funds Obligated to Date: |
FY 2019 = $154,783.00 FY 2020 = $250,839.00 |
History of Investigator: |
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Recipient Sponsored Research Office: |
615 W 131ST ST NEW YORK NY US 10027-7922 (212)854-6851 |
Sponsor Congressional District: |
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Primary Place of Performance: |
61 Route 9W Palisades NY US 10964-1707 |
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): | Paleoclimate |
Primary Program Source: |
01001920DB NSF RESEARCH & RELATED ACTIVIT 01002021DB 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
The potential Broader Impacts include the potential for better understanding the South American monsoon, for filling in sparse hydroclimate records, and for fuller understanding climate variability. Collaboration with South American colleagues is planned as is extensive student involvement.
This project aims to employ classical dendrochronological techniques to generate new tropical tree-ring chronologies that are annually resolved and absolutely dated. Radiocarbon measurements (14-Carbon) will ensure accurate dating assessments. Thus, successful tree species will be selected to improve the 14-Carbon curve for the Southern Hemisphere. The resulting tree-ring series will be used to reconstruct past climate variability and regional to large--scale atmospheric dynamics for the last several centuries. The specific aims of the project are to improve understanding of: (1) the spatiotemporal variability of the South American summer monsoon (SASM); (2) long-term interactions between El Niño-Southern Oscillation (ENSO) and the SASM; and (3) the impact of volcanic forcing on past hydroclimate of the tropical Andes.
The research aims to provide significant advances in the science of tropical dendrochronology by
developing a tree-ring network for the tropical Andes in Peru and Bolivia, a region with exceedingly scarce coverage of high-resolution terrestrial paleo-records. While tree rings have been extensively used in temperate climates, the tropics remain relatively unexplored due to the difficulty, in particular, of identifying consistent wood layers (tree rings) corresponding to seasonal or annual growing periods. The Central Andes are an ideal region for overcoming these difficulties, due to the pronounced precipitation seasonality and diverse forests.
The tropical Andes are a hotspot for biodiversity and its geographic position makes it extremely vulnerable to climate change. It also contains nearly all the tropical glaciers on the globe, and recent, widespread glacial retreat is causing a rapid decline in hydrological reserves. This decline, in combination with increasing water demand due to population growth and economic expansion poses an enormous challenge for water availability, biodiversity and food security. The complex topography of the Andean Cordillera leads to a climate that is characterized by strong zonal and vertical precipitation gradients. Moisture influx from the tropical Atlantic Ocean and the Amazon basin is modulated by the SASM and ENSO. The scientific understanding of this variability is challenged by the scarcity of long instrumental observations, which also limits the ability to constrain uncertainties in future climate change projections over this region.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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.
The main goal of this project was to address fundamental questions related to how climate, and specifically hydroclimate, has varied across the tropical Andes of South America over the past several hundred years. Such information cannot be provided from the short and sparsely distributed instrumental records currently available. Therefore, we utilized longer, high-resolution (annual or seasonal) so-called 'proxy' data derived from precisely-dated tree-ring wood samples.
For this project, numerous chronologies have been established across the central tropical Andes, representing more than 36 tree species native to Ecuador, Peru, Bolivia, and Chile. Some of these chronologies were generated from newly described species in dendrochronology, considerably expanding the list of suitable species for such studies. We supplemented traditional dating methods (i.e. tree-ring width) using the techniques of radiocarbon and wood anatomical analysis to clarify ring boundaries and confirm annual periodicity in species where traditional methods alone may be insufficient. We discovered that stable oxygen isotopes in tree rings are valid recorders of precipitation (rainfall) variability during the wet season, and that timeseries of various wood anatomical features can provide novel information independent of the width of the rings. Our innovative approaches and analyses offer valuable insight into the interrelationships between tropical climate patterns and tree growth dynamics. This research has improved our understanding of: (1) the variability of the South American summer monsoon (SASM), a key feature of tropical climate across our study region; (2) long-term interactions between the SASM and the global El Nino-Southern Oscillation (ENSO) system; and (3) the impact of volcanic cooling on the past hydroclimate of the tropical Andes.
Lastly, we note that this project is an intensive, collaborative effort between scientists at the Tree-Ring Lab of the Lamont-Doherty Earth Observatory of Columbia University (TRL-LDEO), the University of California - Irvine and the State University at Albany, New York. Multiple educational and research opportunities and activities were provided for scientists, students and other personnel at these institutions as well as those of our South American collaborators. Besides field and lab training, collaborative peer-reviewed papers are being published in key journals and the results presented at scientific conferences around the world. Importantly, our achievements and key findings are the direct result of synergies forged between the co-PIs of this project and our South American partners.
Last Modified: 07/12/2023
Modified by: Laia Andreu-Hayles
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