Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet

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 previo...

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Published in:The Cryosphere
Main Authors: J. M. Cook, A. J. Tedstone, C. Williamson, J. McCutcheon, A. J. Hodson, A. Dayal, M. Skiles, S. Hofer, R. Bryant, O. McAree, A. McGonigle, J. Ryan, A. M. Anesio, T. D. L. Irvine-Fynn, A. Hubbard, E. Hanna, M. Flanner, S. Mayanna, L. G. Benning, D. van As, M. Yallop, J. B. McQuaid, T. Gribbin, M. Tranter
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2020
Subjects:
geo
Online Access:https://doi.org/10.5194/tc-14-309-2020
https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf
https://doaj.org/article/f870750b981e47dfb6e844de2c42f2a2
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spelling fttriple:oai:gotriple.eu:oai:doaj.org/article:f870750b981e47dfb6e844de2c42f2a2 2023-05-15T16:21:30+02:00 Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet J. M. Cook A. J. Tedstone C. Williamson J. McCutcheon A. J. Hodson A. Dayal M. Skiles S. Hofer R. Bryant O. McAree A. McGonigle J. Ryan A. M. Anesio T. D. L. Irvine-Fynn A. Hubbard E. Hanna M. Flanner S. Mayanna L. G. Benning D. van As M. Yallop J. B. McQuaid T. Gribbin M. Tranter 2020-01-01 https://doi.org/10.5194/tc-14-309-2020 https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf https://doaj.org/article/f870750b981e47dfb6e844de2c42f2a2 en eng Copernicus Publications doi:10.5194/tc-14-309-2020 1994-0416 1994-0424 https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf https://doaj.org/article/f870750b981e47dfb6e844de2c42f2a2 undefined The Cryosphere, Vol 14, Pp 309-330 (2020) envir geo Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2020 fttriple https://doi.org/10.5194/tc-14-309-2020 2023-01-22T19:27:58Z 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 26.15±3.77 % (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 km2 area around our field site, 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 ... Article in Journal/Newspaper glacier Greenland Ice Sheet The Cryosphere Unknown Greenland The Cryosphere 14 1 309 330
institution Open Polar
collection Unknown
op_collection_id fttriple
language English
topic envir
geo
spellingShingle envir
geo
J. M. Cook
A. J. Tedstone
C. Williamson
J. McCutcheon
A. J. Hodson
A. Dayal
M. Skiles
S. Hofer
R. Bryant
O. McAree
A. McGonigle
J. Ryan
A. M. Anesio
T. D. L. Irvine-Fynn
A. Hubbard
E. Hanna
M. Flanner
S. Mayanna
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
topic_facet envir
geo
description 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 26.15±3.77 % (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 km2 area around our field site, 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 ...
format Article in Journal/Newspaper
author J. M. Cook
A. J. Tedstone
C. Williamson
J. McCutcheon
A. J. Hodson
A. Dayal
M. Skiles
S. Hofer
R. Bryant
O. McAree
A. McGonigle
J. Ryan
A. M. Anesio
T. D. L. Irvine-Fynn
A. Hubbard
E. Hanna
M. Flanner
S. Mayanna
L. G. Benning
D. van As
M. Yallop
J. B. McQuaid
T. Gribbin
M. Tranter
author_facet J. M. Cook
A. J. Tedstone
C. Williamson
J. McCutcheon
A. J. Hodson
A. Dayal
M. Skiles
S. Hofer
R. Bryant
O. McAree
A. McGonigle
J. Ryan
A. M. Anesio
T. D. L. Irvine-Fynn
A. Hubbard
E. Hanna
M. Flanner
S. Mayanna
L. G. Benning
D. van As
M. Yallop
J. B. McQuaid
T. Gribbin
M. Tranter
author_sort J. M. Cook
title 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_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_sort glacier algae accelerate melt rates on the south-western greenland ice sheet
publisher Copernicus Publications
publishDate 2020
url https://doi.org/10.5194/tc-14-309-2020
https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf
https://doaj.org/article/f870750b981e47dfb6e844de2c42f2a2
geographic Greenland
geographic_facet Greenland
genre glacier
Greenland
Ice Sheet
The Cryosphere
genre_facet glacier
Greenland
Ice Sheet
The Cryosphere
op_source The Cryosphere, Vol 14, Pp 309-330 (2020)
op_relation doi:10.5194/tc-14-309-2020
1994-0416
1994-0424
https://www.the-cryosphere.net/14/309/2020/tc-14-309-2020.pdf
https://doaj.org/article/f870750b981e47dfb6e844de2c42f2a2
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op_doi https://doi.org/10.5194/tc-14-309-2020
container_title The Cryosphere
container_volume 14
container_issue 1
container_start_page 309
op_container_end_page 330
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