Aarhus University Seal

Dansk

You are here: » Algal photophysiology drives darkening and melt of the Gr...

About Aarhus University

Algal photophysiology drives darkening and melt of the Greenland Ice Sheet

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Standard

Algal photophysiology drives darkening and melt of the Greenland Ice Sheet. / Williamson, Christopher J.; Cook, Joseph; Tedstone, Andrew et al.
In: Proceedings of the National Academy of Sciences, Vol. 117, No. 11, 17.03.2020, p. 5694-5705.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Harvard

Williamson, CJ, Cook, J, Tedstone, A, Yallop, M, McCutcheon, J, Poniecka, E, Campbell, D, Irvine-Fynn, T, McQuaid, J, Tranter, M, Perkins, R & Anesio, A 2020, 'Algal photophysiology drives darkening and melt of the Greenland Ice Sheet', Proceedings of the National Academy of Sciences, vol. 117, no. 11, pp. 5694-5705. https://doi.org/10.1073/pnas.1918412117

APA

Williamson, C. J., Cook, J., Tedstone, A., Yallop, M., McCutcheon, J., Poniecka, E., Campbell, D., Irvine-Fynn, T., McQuaid, J., Tranter, M., Perkins, R., & Anesio, A. (2020). Algal photophysiology drives darkening and melt of the Greenland Ice Sheet. Proceedings of the National Academy of Sciences, 117(11), 5694-5705. https://doi.org/10.1073/pnas.1918412117

CBE

Williamson CJ, Cook J, Tedstone A, Yallop M, McCutcheon J, Poniecka E, Campbell D, Irvine-Fynn T, McQuaid J, Tranter M, et al. 2020. Algal photophysiology drives darkening and melt of the Greenland Ice Sheet. Proceedings of the National Academy of Sciences. 117(11):5694-5705. https://doi.org/10.1073/pnas.1918412117

MLA

Williamson, Christopher J. et al. "Algal photophysiology drives darkening and melt of the Greenland Ice Sheet". Proceedings of the National Academy of Sciences. 2020, 117(11). 5694-5705. https://doi.org/10.1073/pnas.1918412117

Vancouver

Williamson CJ, Cook J, Tedstone A, Yallop M, McCutcheon J, Poniecka E et al. Algal photophysiology drives darkening and melt of the Greenland Ice Sheet. Proceedings of the National Academy of Sciences. 2020 Mar 17;117(11):5694-5705. doi: 10.1073/pnas.1918412117

Author

Williamson, Christopher J. ; Cook, Joseph ; Tedstone, Andrew et al. / Algal photophysiology drives darkening and melt of the Greenland Ice Sheet. In: Proceedings of the National Academy of Sciences. 2020 ; Vol. 117, No. 11. pp. 5694-5705.

Bibtex

@article{c926cf9abe6c49e0ae43d1d801449e83,
title = "Algal photophysiology drives darkening and melt of the Greenland Ice Sheet",
abstract = "Blooms of Zygnematophycean “glacier algae” lower the bare ice albedo of the Greenland Ice Sheet (GrIS), amplifying summer en- ergy absorption at the ice surface and enhancing meltwater runoff from the largest cryospheric contributor to contemporary sea-level rise. Here, we provide a step change in current understanding of algal-driven ice sheet darkening through quantification of the photophysiological mechanisms that allow glacier algae to thrive on and darken the bare ice surface. Significant secondary phe- nolic pigmentation (11 times the cellular content of chlorophyll a) enables glacier algae to tolerate extreme irradiance (up to ∼4,000 μmol photons·m−2·s−1) while simultaneously repurposing captured ultraviolet and short-wave radiation for melt generation. Total cellular energy absorption is increased 50-fold by pheno- lic pigmentation, while glacier algal chloroplasts positioned be- neath shading pigments remain low-light–adapted (Ek ∼46 μmol photons·m−2·s−1) and dependent upon typical nonphotochemical quenching mechanisms for photoregulation. On the GrIS, glacier algae direct only ∼1 to 2.4% of incident energy to photochemistry versus 48 to 65% to ice surface melting, contributing an additional ∼1.86 cm water equivalent surface melt per day in patches of high algal abundance (∼104 cells·mL−1). At the regional scale, surface darkening is driven by the direct and indirect impacts of glacier algae on ice albedo, with a significant negative relationship between broadband albedo (Moderate Resolution Imaging Spectroradiometer [MODIS]) and glacier algal biomass (R2 = 0.75, n = 149), indicating that up to 75% of the variability in albedo across the southwestern GrIS may be attributable to the presence of glacier algae.",
keywords = "Cryosphere, Glacier algae, Greenland Ice Sheet, Melt, Photophysiology",
author = "Williamson, {Christopher J.} and Joseph Cook and Andrew Tedstone and Marian Yallop and Jenine McCutcheon and Ewa Poniecka and Douglas Campbell and Tristram Irvine-Fynn and James McQuaid and Martyn Tranter and Rupert Perkins and Alexandre Anesio",
year = "2020",
month = mar,
day = "17",
doi = "10.1073/pnas.1918412117",
language = "English",
volume = "117",
pages = "5694--5705",
journal = "Proceedings of the National Academy of Sciences",
issn = "0027-8424",
publisher = "The National Academy of Sciences of the United States of America",
number = "11",

}

RIS

TY - JOUR

T1 - Algal photophysiology drives darkening and melt of the Greenland Ice Sheet

AU - Williamson, Christopher J.

AU - Cook, Joseph

AU - Tedstone, Andrew

AU - Yallop, Marian

AU - McCutcheon, Jenine

AU - Poniecka, Ewa

AU - Campbell, Douglas

AU - Irvine-Fynn, Tristram

AU - McQuaid, James

AU - Tranter, Martyn

AU - Perkins, Rupert

AU - Anesio, Alexandre

PY - 2020/3/17

Y1 - 2020/3/17

N2 - Blooms of Zygnematophycean “glacier algae” lower the bare ice albedo of the Greenland Ice Sheet (GrIS), amplifying summer en- ergy absorption at the ice surface and enhancing meltwater runoff from the largest cryospheric contributor to contemporary sea-level rise. Here, we provide a step change in current understanding of algal-driven ice sheet darkening through quantification of the photophysiological mechanisms that allow glacier algae to thrive on and darken the bare ice surface. Significant secondary phe- nolic pigmentation (11 times the cellular content of chlorophyll a) enables glacier algae to tolerate extreme irradiance (up to ∼4,000 μmol photons·m−2·s−1) while simultaneously repurposing captured ultraviolet and short-wave radiation for melt generation. Total cellular energy absorption is increased 50-fold by pheno- lic pigmentation, while glacier algal chloroplasts positioned be- neath shading pigments remain low-light–adapted (Ek ∼46 μmol photons·m−2·s−1) and dependent upon typical nonphotochemical quenching mechanisms for photoregulation. On the GrIS, glacier algae direct only ∼1 to 2.4% of incident energy to photochemistry versus 48 to 65% to ice surface melting, contributing an additional ∼1.86 cm water equivalent surface melt per day in patches of high algal abundance (∼104 cells·mL−1). At the regional scale, surface darkening is driven by the direct and indirect impacts of glacier algae on ice albedo, with a significant negative relationship between broadband albedo (Moderate Resolution Imaging Spectroradiometer [MODIS]) and glacier algal biomass (R2 = 0.75, n = 149), indicating that up to 75% of the variability in albedo across the southwestern GrIS may be attributable to the presence of glacier algae.

AB - Blooms of Zygnematophycean “glacier algae” lower the bare ice albedo of the Greenland Ice Sheet (GrIS), amplifying summer en- ergy absorption at the ice surface and enhancing meltwater runoff from the largest cryospheric contributor to contemporary sea-level rise. Here, we provide a step change in current understanding of algal-driven ice sheet darkening through quantification of the photophysiological mechanisms that allow glacier algae to thrive on and darken the bare ice surface. Significant secondary phe- nolic pigmentation (11 times the cellular content of chlorophyll a) enables glacier algae to tolerate extreme irradiance (up to ∼4,000 μmol photons·m−2·s−1) while simultaneously repurposing captured ultraviolet and short-wave radiation for melt generation. Total cellular energy absorption is increased 50-fold by pheno- lic pigmentation, while glacier algal chloroplasts positioned be- neath shading pigments remain low-light–adapted (Ek ∼46 μmol photons·m−2·s−1) and dependent upon typical nonphotochemical quenching mechanisms for photoregulation. On the GrIS, glacier algae direct only ∼1 to 2.4% of incident energy to photochemistry versus 48 to 65% to ice surface melting, contributing an additional ∼1.86 cm water equivalent surface melt per day in patches of high algal abundance (∼104 cells·mL−1). At the regional scale, surface darkening is driven by the direct and indirect impacts of glacier algae on ice albedo, with a significant negative relationship between broadband albedo (Moderate Resolution Imaging Spectroradiometer [MODIS]) and glacier algal biomass (R2 = 0.75, n = 149), indicating that up to 75% of the variability in albedo across the southwestern GrIS may be attributable to the presence of glacier algae.

KW - Cryosphere

KW - Glacier algae

KW - Greenland Ice Sheet

KW - Melt

KW - Photophysiology

UR - http://www.scopus.com/inward/record.url?scp=85081677987&partnerID=8YFLogxK

U2 - 10.1073/pnas.1918412117

DO - 10.1073/pnas.1918412117

M3 - Journal article

C2 - 32094168

AN - SCOPUS:85081677987

VL - 117

SP - 5694

EP - 5705

JO - Proceedings of the National Academy of Sciences

JF - Proceedings of the National Academy of Sciences

SN - 0027-8424

IS - 11

ER -