| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | July 19, 2019 |
| Latest Amendment Date: | July 19, 2019 |
| Award Number: | 1904128 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Rainer Amon
OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | August 1, 2019 |
| End Date: | July 31, 2023 (Estimated) |
| Total Intended Award Amount: | $532,526.00 |
| Total Awarded Amount to Date: | $532,526.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
4333 BROOKLYN AVE NE SEATTLE WA US 98195-1016 (206)543-4043 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
4333 Brooklyn Ave NE Seattle WA US 98195-0001 |
| 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): |
Atmospheric Chemistry, ANS-Arctic Natural Sciences |
| Primary Program Source: |
0100XXXXDB 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): | 47.078 |
ABSTRACT
In recent decades, the Arctic has experienced the most rapid rate of warming around the globe. Satellite observations show that sea ice has been declining since at least 1980. The Arctic is projected to be ice-free during summer starting between 2050-2100 C.E. Both the open ocean and sea ice host a range of microscopic algal or phytoplankton communities, and the response of these algal communities to melting sea ice can be important to both the marine and atmospheric environment, but is unknown. This project aims to detect, describe and understand such response by studying sulfur-containing substances preserved in a Greenland ice core. Oceanic phytoplankton are the largest natural source of sulfur aerosol to the atmosphere. Sulfur-containing aerosol has a cooling impact on climate because it efficiently reflects sunlight back to space. As the emission of sulfate from combustion of fossil fuels has declined due to effective air pollution mitigation, natural sources are becoming more important. However, it is unclear how decreasing sea ice affects the abundance of natural sulfate aerosol in the Arctic. This project will measure two indicators of the phytoplankton source of sulfur aerosol in a Greenland ice core record dating from 1200 - 2006 C.E. These measurements will reveal any trends in the phytoplankton source of sulfur aerosol resulting from melting sea ice, and will inform future predictions of Arctic primary productivity and climate. Insight from this project will prove valuable for forecasting the future response of phytoplankton emissions and climate-cooling aerosols to melting sea ice. This award will provide training for two graduate and several undergraduate students at the University of Washington and South Dakota State University, and will support outreach activities such as demonstrations at the annual Polar Science Weekend at the Pacific Science Center in Seattle, WA.
This award will support measurements of the sulfur isotopic composition of sulfate and the concentration of methanesulfonic acid (MSA) in a Greenland ice core dating from 1200 - 2006 C.E. Oceanic phytoplankton emit dimethylsufide (DMS) into the atmosphere. Once in the atmosphere, DMS is oxidized to the sulfur aerosols sulfate and MSA. Sulfur isotopes of sulfate originating from DMS oxidation are distinct from other sources of sulfate, while MSA originates only from DMS oxidation. This project will provide the first observational constraint on variations in the phytoplankton source of sulfur aerosol over the past 800 years, with a particular focus on the last 35 years of the record when we know that Arctic sea ice has declined. Global model sensitivity studies will complement the ice-core record by providing insight into the sensitivity of the abundance of Arctic sulfur aerosol to phytoplankton emissions and transport, and provide quantitative insight into the climate impacts of this natural source of sulfur aerosol.
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.
INTELLECTUAL MERIT
Emissions of pollutants to the atmosphere from human activities have had a profound impact on the chemical composition of the Arctic atmosphere and climate. Pollutant emissions in North America and Europe led to Arctic haze conditions that peaked in the 1980s, with subsequent decreases resulting from air pollution-mitigation policies. Since sulfate aerosols cool the climate, the decrease in sulfate aerosol plays a significant role in recent Arctic warming. Natural sources of sulfate aerosol are becoming increasingly important as human sources decline. The magnitude of the climate impact of sulfate aerosol from human activity depends in large part on how important the human sources are relative to the natural sources. This project found that volcanic emissions from degassing volcanoes are underestimated in climate models leading to an overestimate of the cooling effect of aerosols from human activity on climate. This project was able to quantify the relative importance of the human source of sulfate aerosol, and quantify the impacts of human activity on trends in sulfate. This will improve climate model estimates of the climate impact of sulfate aerosol from human activity. Finally, we were able to quantify the source of sulfate aerosol from marine phytoplankton which form the base of the Arctic food web. This combined with our measurements of another sulfur aerosol (methanesulfonic acid or MSA) that originates from marine phytoplankton allowed us to determine that sulfur emissions from the ocean have not yet changed as a result of changes to the Arctic climate.
BROADER IMPACTS
By quantifying, for the first time, the importance of different sources of sulfate aerosol to the Arctic, we will improve our understanding of the impact of human activity on the Arctic climate, which is warming at a rate that is four times faster than the rest of the world. In particular, we have improved our understanding of the role of sulfate aerosol from individual natural and human sources, which will inform and improve climate models. The project contributed to the scientific training of five graduate students and five undergraduate students.
Last Modified: 11/20/2023
Modified by: Becky Alexander
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