| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | September 6, 2013 |
| Latest Amendment Date: | September 6, 2013 |
| Award Number: | 1322742 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Justin Lawrence
jlawrenc@nsf.gov (703)292-2425 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2013 |
| End Date: | August 31, 2017 (Estimated) |
| Total Intended Award Amount: | $41,934.00 |
| Total Awarded Amount to Date: | $41,934.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1000 E 5TH ST GREENVILLE NC US 27858-2502 (252)328-9530 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Greenville NC US 27858-4353 |
| 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, Geomorphology & Land-use Dynam |
| 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
Accurate projections of future relative sea-level (RSL) rise are crucial for effective management of coastal populations, infrastructure, and ecosystems including salt marshes. Sea-level reconstructions from the last 4000 years provide a context for understanding modern and projected rates of sea-level rise because Earth's climate system is relatively unchanged. We will develop two new proxy RSL reconstructions from North Carolina to identify positive and negative departures from the perceived stability of sea level during the last 4000 years and support development of new predictive models in which the sea level-climate relationship can vary through time. The reconstructions will test the widely held assumption that sea-level rise from melting of large ice sheets was negligible during the last 2000 years and will help constrain rates of vertical land level movement. Data generated for the reconstructions will be used to further develop a model of salt-marsh response to sea-level rise that will provide a valuable service and tool to the coastal management community for informing policy decisions.
While there are compilations of global and regional proxy temperature data for the late Holocene, little is known about sea-level variability during this period and the response of sea level to known climate deviations such as the Medieval Climate Anomaly, Little Ice Age, and 20th century warming is unknown. Using foraminifera preserved in North Carolina salt-marsh sediments, we will produce the first continuous, high resolution (decadal and decimeter) RSL reconstruction spanning the last ~4000 years. The sea-level reconstructions will calibrate new predictive models of sea-level rise to improve the accuracy and regional validity of projections. The new record will extend existing reconstructions to test the following hypotheses that are vital for understanding the climate sea-level relationship: (1) regional RSL was stable before AD 1000; and (2) the contribution from melting of large ice sheets sea-level rise ended 2000 years ago. Reconstructions derived from salt marsh sediment also provide a paleo perspective for predicting the ecological effects of future sea-level rise. The proxy sea-level record will validate, for the first time, the Marsh Equilibrium Model (MEM). The MEM describes the regulation of salt-marsh vegetation by changes in sea level. If sea-level rise is faster than the rate of salt-marsh sediment accretion, the productivity of salt-marsh vegetation will decline, resulting in the degradation or loss of these important coastal ecosystems. The proxy sea level record will test a central premise of the MEM that (3) Stable sediment organic matter (SOM) concentration varies inversely with the reconstructed rate of RSL-rise.
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.
Understanding the rate and amount of past sea-level changes helps us to estimate the scale and scope of sea-level changes that might occur in the future. Understading the realm of possibilities for future sea-level change, and the reasons for local and regional variation in rate and/or amount is important for coastal managers, policy makers, coastal residents and owners/managers of coastal infrastructure including docks, industrial centers, petroleum storage facilities and military installations and bases. This study in coastal North Carolina demonstrated that locations just 100 km apart, in what seem to be identical environmental settings, can have significantly different sea-level histories. At Cedar Island, relative sea level rose by ~2.4 m during the past ~3000 years. Over the same interval, relative sea level rose ~3.3 m at Roanoke Island. Further, the Roanoke Island record exhibits a period (from 1400 to 900 years ago) of accelerating sea-level rise that is not seen at Cedar Island. What are the driving mechanisms for these regional variations? In this case, tidal-range, sediment dynamics and sediment compaction variations cannot adequately explain the different sea-level histories. Instead, the differences, when placed in the broader context of sea-level changes from Florida to Connecticut, are best explained as a local- to regional-scale effect of dynamic ocean and/or atmosperic circulation in the North Atlantic Ocean region.
Last Modified: 09/20/2017
Modified by: Stephen Culver
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