Greenland Climate of the Past & Present

Last summer, several IGERT fellows had the serendipitous and rare opportunity to witness a warming climate’s effect on Greenland first-hand. Julia Bradley-Cook was stationed in Kangerlussuaq collecting data on carbon cycling in soil when the bridge over the Watson river collapsed from anomalously high flows of meltwater (see https://dartmouthigert.wordpress.com/2012/07/11/glacial-melt-threatens-town-water-supply and https://dartmouthigert.wordpress.com/2012/07/11/update-the-river-powers-on). Days later, the 3rd cohort of Dartmouth IGERT students flew up to Summit Camp, Greenland’s highest point, and observed features of the ice sheet-wide surface melt. Fellow Kaitlin Keegan, Thayer Professor Mary Albert, and their collaborators study the frequency of such melt events; their work at the North Greenland Eemian Ice Drilling (NEEM) sight has suggested that such an event last transpired in 1889 and, therefore, is unprecedented in the satellite record. (See https://dartmouthigert.wordpress.com/2012/07/21/new-summit-melt-layer).

A new Nature publication on Greenland climate authored by the NEEM community, which includes Albert and Keegan, prompted an entry on the scientific blog site RealClimate.org. RealClimate was started and is maintained by “working climate scientists” who “aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary.” Check out the discussion on Greenland’s 2012 summer conditions, how they compare to those 125,000 years ago, and what we can learn about past temperatures and sea level rise from an ice core! I was particularly excited about the conclusion of the entry since author Dr. Steig mentioned the significance of a new ice core from West Antarctica. I just returned from a field season on Roosevelt Island assisting with the drilling of this core, which will help scientists understand the sensitivity of the Ross Ice Shelf and, thus, of the West Antarctic ice sheet to changes in climate. http://www.realclimate.org/index.php/archives/2013/01/the-greenland-melt/

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Excitement at Summit Station

This post was written by Professor Mary Albert

Our NSF-IGERT studies at Summit, Greenland are designed to investigate aspects of snow, firn, and ice core interpretation, as part of our larger look at polar environmental change in Greenland. Coming to the site of the GISP2 ice core, where ice core scientists first realized that climate could change in less than ten years, is a real adventure for our graduate students! Being here now to witness a new change and to measure its effects  — the first significant melt at this cold high-altitude site since 1889 – is but one of the great opportunities to showcase the excitement of working in polar science!  The National Science Foundation has facilitated this unusual and extremely educational opportunity in this brief round of science here at Summit, the very top of the Greenland Ice Sheet.

Our third-year IGERT student, Kaitlin Keegan, came up earlier to conduct snow science with the JSEP group of high school students; she then left Summit before our arrival to venture on to the NEEM site. I have thoroughly enjoyed the honor of leading the discoveries with our first-year IGERT students – what a bright group of PhD students they are!

The Dartmouth IGERT group at Summit. From left to right: Mary Albert, Stephanie Gregory, Lee Corbett, Jessica Trout-Haney, Chelsea Vario, Alexandra Giese, and Ian Baker

We made stratigraphy, density, and permeability measurements on important layers in the snow.

Stephanie Gregory and Mary Albert discuss a snow sample for a permeability measurement.

We collected samples of the refrozen melt layer to take home for more detailed measurements. Hey, even our panda got a taste of ice science!

Being at Summit immediately after the first big melt there since 1889 has been a great science & education opportunity!  We are all very thankful to the NSF IGERT program for supporting these students, the NSF Office of Polar Programs for allowing us to come to Summit, the Air National Guard for getting us to Greenland, and to all of the wonderful folks at CH2Mhill Polar Services for providing superior field support, including the extremely capable camp staff at Summit Station.  A very hearty Thank You to you all!

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New Summit Melt Layer

I arrived at Summit Station on July 13th, while traveling with the
Joint Science and Education Program (JSEP) for a short visit to the
camp. When we arrived, Summit Station had been experiencing above
freezing temperatures for multiple days prior to our arrival and a
melt layer formed on the near surface snow. I have been studying the
physical properties of the top layers of the ice, the firn, at Summit
and NEEM for my Ph.D. research. Recently, I have been focused on the
melt layers present in both firn cores because they occur very
infrequently. At Summit, there is only one other melt layer besides
the melt layer from this past week and this previous melt layer dates
to 1889.

The most interesting part of being at Summit Station just after a melt
event had occurred, is that the melt layer formation process could be
observed. When studying a firn core, there is only a small cross
section of the firn column that can be examined, which makes it hard
to understand how the melt layer formed and how evenly distributed it
is. Studying snow pits at Summit, including the recent melt layer,
presents a unique opportunity for us to understand how previous melt
events occurred. While at Summit density, stratigraphy, and
permeability measurements have been taken and samples will also be
brought back to the laboratory at Dartmouth, which will give us a clue
about melt layers in the past.

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