Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet
<p>Melting of the Greenland Ice Sheet (GrIS) is the largest single contributor to eustatic sea level and is amplified by the growth of pigmented algae on the ice surface, which increases solar radiation absorption. This biological albedo-reducing effect and its impact upon sea level rise has n...
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Copernicus Publications
2020-01-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf |
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| author | J. M. Cook J. M. Cook A. J. Tedstone C. Williamson J. McCutcheon A. J. Hodson A. J. Hodson A. Dayal A. Dayal M. Skiles S. Hofer R. Bryant O. McAree A. McGonigle A. McGonigle J. Ryan A. M. Anesio T. D. L. Irvine-Fynn A. Hubbard E. Hanna M. Flanner S. Mayanna L. G. Benning L. G. Benning L. G. Benning D. van As M. Yallop J. B. McQuaid T. Gribbin M. Tranter |
| author_facet | J. M. Cook J. M. Cook A. J. Tedstone C. Williamson J. McCutcheon A. J. Hodson A. J. Hodson A. Dayal A. Dayal M. Skiles S. Hofer R. Bryant O. McAree A. McGonigle A. McGonigle J. Ryan A. M. Anesio T. D. L. Irvine-Fynn A. Hubbard E. Hanna M. Flanner S. Mayanna L. G. Benning L. G. Benning L. G. Benning D. van As M. Yallop J. B. McQuaid T. Gribbin M. Tranter |
| author_sort | J. M. Cook |
| collection | DOAJ |
| description | <p>Melting of the Greenland Ice Sheet (GrIS) is the largest
single contributor to eustatic sea level and is amplified by the growth
of pigmented algae on the ice surface, which increases solar radiation
absorption. This biological albedo-reducing effect and its impact upon sea
level rise has not previously been quantified. Here, we combine field
spectroscopy with a radiative-transfer model, supervised classification of
unmanned aerial vehicle (UAV) and satellite remote-sensing data, and runoff modelling to calculate
biologically driven ice surface ablation. We demonstrate that algal growth
led to an additional 4.4–6.0 Gt of runoff from bare ice in the
south-western sector of the GrIS in summer 2017, representing 10 %–13 %
of the total. In localized patches with high biomass accumulation, algae
accelerated melting by up to <span class="inline-formula">26.15±3.77</span> % (standard error, SE). The year 2017
was a high-albedo year, so we also extended our analysis to the particularly low-albedo 2016 melt season. The runoff from the south-western bare-ice zone attributed to algae was much higher in 2016 at 8.8–12.2 Gt, although the
proportion of the total runoff contributed by algae was similar at 9 %–13 %. Across a 10 000 km<span class="inline-formula"><sup>2</sup></span> area around our field site,<span id="page310"/> algae covered
similar proportions of the exposed bare ice zone in both years (57.99 %
in 2016 and 58.89 % in 2017), but more of the algal ice was classed as
“high biomass” in 2016 (8.35 %) than 2017 (2.54 %). This interannual
comparison demonstrates a positive feedback where more widespread, higher-biomass algal blooms are expected to form in high-melt years where the
winter snowpack retreats further and earlier, providing a larger area for bloom
development and also enhancing the provision of nutrients and liquid water
liberated from melting ice. Our analysis confirms the importance of this
biological albedo feedback and that its omission from predictive models
leads to the systematic underestimation of Greenland's future sea level
contribution, especially because both the bare-ice zones available for algal
colonization and the length of the biological growth season are set to
expand in the future.</p> |
| first_indexed | 2024-12-19T13:39:10Z |
| format | Article |
| id | doaj.art-f870750b981e47dfb6e844de2c42f2a2 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-19T13:39:10Z |
| publishDate | 2020-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-f870750b981e47dfb6e844de2c42f2a22022-12-21T20:19:04ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242020-01-011430933010.5194/tc-14-309-2020Glacier algae accelerate melt rates on the south-western Greenland Ice SheetJ. M. Cook0J. M. Cook1A. J. Tedstone2C. Williamson3J. McCutcheon4A. J. Hodson5A. J. Hodson6A. Dayal7A. Dayal8M. Skiles9S. Hofer10R. Bryant11O. McAree12A. McGonigle13A. McGonigle14J. Ryan15A. M. Anesio16T. D. L. Irvine-Fynn17A. Hubbard18E. Hanna19M. Flanner20S. Mayanna21L. G. Benning22L. G. Benning23L. G. Benning24D. van As25M. Yallop26J. B. McQuaid27T. Gribbin28M. Tranter29Department of Geography, University of Sheffield, Winter Street, Sheffield, South Yorkshire, S10 2TN, UKInstitute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3DA, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Berkely Square, Bristol, BS8 1RL, UKSchool of Biological Sciences, University of Bristol, Tyndall Ave, Bristol, BS8 1TQ, UKSchool of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UKDepartment of Geology, University Centre in Svalbard, Longyearbyen, 9171, NorwayDepartment of Environmental Sciences, Western Norway University of Applied Sciences, 6856 Sogndal, NorwayDepartment of Geography, University of Sheffield, Winter Street, Sheffield, South Yorkshire, S10 2TN, UKDepartment of Geology, University Centre in Svalbard, Longyearbyen, 9171, NorwayDepartment of Geography, University of Utah, Central Campus Dr, Salt Lake City, Utah, USABristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Berkely Square, Bristol, BS8 1RL, UKDepartment of Geography, University of Sheffield, Winter Street, Sheffield, South Yorkshire, S10 2TN, UKFaculty of Science, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool, L3 3AF, UKDepartment of Geography, University of Sheffield, Winter Street, Sheffield, South Yorkshire, S10 2TN, UKSchool of Geosciences, University of Sydney, Sydney, NSW 2006, AustraliaInstitute at Brown for Environment and Society, Brown University, Providence, Rhode Island, USADepartment of Environmental Science, Aarhus University, 4000 Roskilde, DenmarkDepartment of Geography and Earth Science, Aberystwyth University, Wales, SY23 3DB, UKCentre for Gas Hydrate, Environment and Climate, University of Tromsø, 9010 Tromsø, NorwaySchool of Geography and Lincoln Centre for Water and Planetary Health, University of Lincoln, Think Tank, Ruston Way, Lincoln, LN6 7DW, UKClimate and Space Sciences and Engineering, University of Michigan, 2455 Hayward St. Ann Arbor, Michigan, USAGerman Research Centre for Geosciences, GFZ, Potsdam, GermanySchool of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UKGerman Research Centre for Geosciences, GFZ, Potsdam, GermanyDepartment of Earth Sciences, University of Berlin, Berlin, GermanyGeological Survey of Denmark and Greenland, Copenhagen, DenmarkSchool of Biological Sciences, University of Bristol, Tyndall Ave, Bristol, BS8 1TQ, UKSchool of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Berkely Square, Bristol, BS8 1RL, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Berkely Square, Bristol, BS8 1RL, UK<p>Melting of the Greenland Ice Sheet (GrIS) is the largest single contributor to eustatic sea level and is amplified by the growth of pigmented algae on the ice surface, which increases solar radiation absorption. This biological albedo-reducing effect and its impact upon sea level rise has not previously been quantified. Here, we combine field spectroscopy with a radiative-transfer model, supervised classification of unmanned aerial vehicle (UAV) and satellite remote-sensing data, and runoff modelling to calculate biologically driven ice surface ablation. We demonstrate that algal growth led to an additional 4.4–6.0 Gt of runoff from bare ice in the south-western sector of the GrIS in summer 2017, representing 10 %–13 % of the total. In localized patches with high biomass accumulation, algae accelerated melting by up to <span class="inline-formula">26.15±3.77</span> % (standard error, SE). The year 2017 was a high-albedo year, so we also extended our analysis to the particularly low-albedo 2016 melt season. The runoff from the south-western bare-ice zone attributed to algae was much higher in 2016 at 8.8–12.2 Gt, although the proportion of the total runoff contributed by algae was similar at 9 %–13 %. Across a 10 000 km<span class="inline-formula"><sup>2</sup></span> area around our field site,<span id="page310"/> algae covered similar proportions of the exposed bare ice zone in both years (57.99 % in 2016 and 58.89 % in 2017), but more of the algal ice was classed as “high biomass” in 2016 (8.35 %) than 2017 (2.54 %). This interannual comparison demonstrates a positive feedback where more widespread, higher-biomass algal blooms are expected to form in high-melt years where the winter snowpack retreats further and earlier, providing a larger area for bloom development and also enhancing the provision of nutrients and liquid water liberated from melting ice. Our analysis confirms the importance of this biological albedo feedback and that its omission from predictive models leads to the systematic underestimation of Greenland's future sea level contribution, especially because both the bare-ice zones available for algal colonization and the length of the biological growth season are set to expand in the future.</p>https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf |
| spellingShingle | J. M. Cook J. M. Cook A. J. Tedstone C. Williamson J. McCutcheon A. J. Hodson A. J. Hodson A. Dayal A. Dayal M. Skiles S. Hofer R. Bryant O. McAree A. McGonigle A. McGonigle J. Ryan A. M. Anesio T. D. L. Irvine-Fynn A. Hubbard E. Hanna M. Flanner S. Mayanna L. G. Benning L. G. Benning L. G. Benning D. van As M. Yallop J. B. McQuaid T. Gribbin M. Tranter Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet The Cryosphere |
| title | Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet |
| title_full | Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet |
| title_fullStr | Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet |
| title_full_unstemmed | Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet |
| title_short | Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet |
| title_sort | glacier algae accelerate melt rates on the south western greenland ice sheet |
| url | https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf |
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