Melt season duration and ice layer formation on the Greenland ice sheet, 2000–2004

ABSTRACTWe present in situ firn temperatures from the extreme 2012 melt season in the southwestern lower accumulation area of the Greenland ice sheet. The upper 2.5 m of snow and firn was temperate during the melt season, when vertical meltwater percolation was inefficient due to a ~5.5 m thick ice layer underlying the temperate firn. Meltwater percolation and refreezing beneath 2.5 m depth only occurred after the melt season. Deviations from temperatures predicted by pure conductivity suggest that meltwater refroze in discrete bands at depths of 2.0–2.5, 5.0–6.0 and 8.0–9.0 m. While we find no indication of meltwater percolation below 9 m depth or complete filling of pore volume above, firn at 10 and 15 m depth was respectively 4.2–4.5°C and 1.7°C higher than in a conductivity-only simulation. Even though meltwater percolation in 2012 was inefficient, firn between 2 and 15 m depth the following winter was on average 4.7°C warmer due to meltwater refreezing. Our observations also suggest that the 2012 firn conditions were preconditioned by two warm summers and ice layer formation in 2010 and 2011. Overall, firn temperatures during the years 2009–13 increased by 0.6°C.

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The Nioghalvfjerdsfjorden glacier project, North-East Greenland: a study of ice sheet response to climatic change

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v176.5073 ◽

1997 ◽

pp. 95-103 ◽

Cited By ~ 5

Author(s):

Henrik Højmark Thomsen ◽

Niels Reeh ◽

Ole B. Olesen ◽

Carl Egede Bøggilde ◽

Wolfgang Starzer ◽

...

Keyword(s):

Climatic Change ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

East Greenland ◽

Changing Climate ◽

North East ◽

Integrated Research ◽

Research Themes ◽

Advance Research ◽

Inland Ice

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Højmark Thomsen, H., Reeh, N., Olesen, O. B., Egede Bøggilde, C., Starzer, W., Weidick, A., & Higgins, A. K. (1997). The Nioghalvfjerdsfjorden glacier project, North-East Greenland: a study of ice sheet response to climatic change. Geology of Greenland Survey Bulletin, 176, 95-103. https://doi.org/10.34194/ggub.v176.5073 _______________ Glaciological research was initiated in 1996 on the floating glacier tongue filling Nioghalvfjerdsfjorden in NorthEast Greenland (Fig. 1), with the aim of acquiring a better understanding of the response of the Greenland ice sheet (Inland Ice) to changing climate, and the implications for future sea level. The research is part of a three year project (1996–98) to advance research into the basic processes that contribute to changes in the ocean volume with a changing climate. Five nations are participants in the project, which is supported by the European Community (EC) Environment and Climate Programme. The Geological Survey of Denmark and Greenland (GEUS) and the Danish Polar Center are the Danish partners in the project, both with integrated research themes concentrated on and around Nioghalvfjerdsfjorden.

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Could climate engineering save the Greenland Ice Sheet?

Climanosco Research Articles - https://www.climanosco.org/collection/climate-change-and-its-impacts/ ◽

10.37207/cra.1.10 ◽

2016 ◽

Author(s):

Patrick J. Applegate ◽

K. Keller

Keyword(s):

Sea Level Rise ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Sea Level ◽

Computer Model ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Upper Atmosphere ◽

Climate Engineering ◽

Air Temperatures

Engineering the climate through albedo modification (AM) could slow, but probably would not stop, melting of the Greenland Ice Sheet. Albedo modification is a technology that could reduce surface air temperatures through putting reflective particles into the upper atmosphere. AM has never been tested, but it might reduce surface air temperatures faster and more cheaply than reducing greenhouse gas emissions. Some scientists claim that AM would also prevent or reverse sea-level rise. But, are these claims true? The Greenland Ice Sheet will melt faster at higher temperatures, adding to sea-level rise. However, it's not clear that reducing temperatures through AM will stop or reverse sea-level rise due to Greenland Ice Sheet melting. We used a computer model of the Greenland Ice Sheet to examine its contributions to future sea level rise, with and without AM. Our results show that AM would probably reduce the rate of sea-level rise from the Greenland Ice Sheet. However, sea-level rise would likely continue even with AM, and the ice sheet would not regrow quickly. Albedo modification might buy time to prepare for sea-level rise, but problems could arise if policymakers assume that AM will stop sea-level rise completely.

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Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes

Journal of Glaciology ◽

10.1017/s0022143000009461 ◽

1990 ◽

Vol 36 (123) ◽

pp. 217-221 ◽

Cited By ~ 25

Author(s):

Roger J. Braithwaite ◽

Ole B. Olesen

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Air Temperature ◽

Sensible Heat Flux ◽

Ice Sheet ◽

Temperature Response ◽

Greenland Ice Sheet ◽

Energy Balance Model ◽

Balance Model ◽

Sensible Heat

AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.

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Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

Nature Geoscience ◽

10.1038/s41561-021-00753-w ◽

2021 ◽

Author(s):

Jon R. Hawkings ◽

Benjamin S. Linhoff ◽

Jemma L. Wadham ◽

Marek Stibal ◽

Carl H. Lamborg ◽

...

Keyword(s):

Natural Waters ◽

Inorganic Mercury ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Annual Runoff ◽

Arctic Ecosystems ◽

High Mercury ◽

Southwestern Margin ◽

High Concentrations ◽

Dissolved Mercury

AbstractThe Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. We show that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments (521–3,300 mmol km−2 year−1) are two orders of magnitude higher than from Arctic rivers (4–20 mmol km−2 year−1). Fluxes of dissolved mercury from the southwestern region of Greenland are estimated to be globally significant (15.4–212 kmol year−1), accounting for about 10% of the estimated global riverine flux, and include export of bioaccumulating methylmercury (0.31–1.97 kmol year−1). High dissolved mercury concentrations (~20 pM inorganic mercury and ~2 pM methylmercury) were found to persist across salinity gradients of fjords. Mean particulate mercury concentrations were among the highest recorded in the literature (~51,000 pM), and dissolved mercury concentrations in runoff exceed reported surface snow and ice values. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting an urgent need to better understand mercury dynamics in ice sheet runoff under global warming.

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