The ERC Synergy Project  Green2Ice project (Green2Ice.eu) met one of its main objectives of the season on June 7th when we found the casing of the GRIP borehole. The GRIP drilling finished in 1992 at 3022 m below the surface but without drilling the deepest ice, which was at that time not considered particularly scientifically valuable. Since then, we have only visited the site briefly for borehole logging and to extend the casing, which gradually sinks into the ice as snow accumulates. But the science has evolved, and for the Green2Ice project, the bottom ice is of utmost importance. We aim to retrieve the deepest ice next year, and that plan relied on finding the old borehole in good shape. In addition, we will drill through to the bedrock and retrieve a core sample of the underlying sediments and bedrock beneath the summit of the Greenland Ice Sheet.

On Friday June 6th, the traverse team moved the traverse train to GRIP. This was possible because our US colleagues at the Summit camp kindly helped us by lending us a spare generator and more petrol, so we could continue despite the problems with our diesel generator. Right after arrival, the team excavated an area (the “mega pit”) above the old GRIP drill dome. The work continued Saturday. Here is the report from the traverse team:

Yesterday we made it a little more than three meter below surface in the center of our mega pit.

Today we ran the snow radar at the bottom of the pit. We saw a clear signal of what could be the casing pretty much at the center of the mega pit. However another 1-2 m further down. We flagged the position and had the Pistenbully dig out another 1.5 m. At the same time, the snow radar was used to confirm the locations of the science trench, utility dome, and main dome.

Meanwhile, the rest of the people prepared for the weatherport to be moved from the sled to the snow surface. However the actual move of that and the last air-force pallet of stuff awaited for the good news that finally arrived 11:00 where Kevin saw the casing lid after the Pistenbully had removed another layer of snow. The casing was found exactly where the snow radar survey of the morning had suggested, and very close to last year’s pit, but much deeper (depth estimated by GPS to 5 m).

Hurray! A celebration was in order before lunch!

We continued borehole logging with a camera and found the casing intact down to a depth of 54 m below the excavated surface. Here, old drill cuttings (aka “chips”) blocked the further penetration of the camera. This is however to be expected – thus again a time for celebration!

A great sunny day – accomplishing the mission of our traverse!

Anders Svensson, one of the four Principal Investigators of the ERC Green2Ice project, is currently waiting in Kangerlussuaq for a flight to the ice cap. He says:

It is absolutely fantastic that the team managed to locate an intact borehole casing at the GRIP site.

Getting access to this borehole was considered one of the high-risk elements of the project. First the exact position of the borehole had to be located based on the maps from the early 1990ies, then there was some uncertainty as to which depth below the snow surface the top of the casing was to found, and finally, there was a risk that the casing would have been damaged from the collapsing drill trench that is buried deep in the firn.

Now when we have found the borehole and it is intact, we can continue with the next step of the project: moving the main camp 350 km from the EGRIP site to GRIP.

Next year, we will attempt to take samples from the deepest part of the ice sheet and from the bedrock below the ice sheet using the old borehole. The scientific goal is to constrain the age of the Greenland ice sheet and determine which climatically warm periods the ice sheet has survived so far.

To achieve these scientific goals, it is key to get sediments buried beneath the ice is key, since they are the only ones to hold information about the timing and duration of the last deglaciation periods. Additionally, state-of-the-art methodologies on fossil remains, organic matter, in-situ-produced and consumed greenhouse gases, and ancient biomolecules will offer insights into the ecosystems and environmental conditions that prevailed during ice-free periods.

Please contact the Green2Ice PI’s for more information on the Green2Ice project  (Green2Ice.eu)  and the plans for the next field season:

Dorthe Dahl-Jensen, University of Copenhagen, +45 2289 4537, ddj@nbi.ku.dk

Anders Svensson, University of Copenhagen, +45 40384410, as@nbi.ku.dk

Pierre-Henri Blard, CRPG, Université de Lorraine, +35 6608 14127, pierre-henri.blard@univ-lorraine.fr

François  Fripiat, Université Libre de Bruxelles, +32 477679356,  francois.fripiat@ulb.be