May 30, 2023

Approaching 100,000 years?

Today we show the 20-year development of the Russell glacier that can be visited from Kangerlussuaq and that many of our field participants have visited over the years. The glacier is connected to the Greenland ice sheet and is a popular sightseeing spot as it is quite impressive. Sune Rasmussen took the upper picture back in 2003 and Iben Koldtoft went out to the glacier yesterday to find the same spot for the lower picture. A rather clear trend.

Drilling continued in a good mode with 4 ice cores drilled today. The two last runs were shorter as there were chips on top of them. The chips are coarse, but appear not always to come up with the core. In the afternoon, the Greendrill Twin-Otter returned from Iceland. Tomorrow they will start shuttling equipment and scientists from the Greendrill site to EGRIP.
We are closely following the age of the ice core as we get deeper into the ice stream. Last week, the EGRIP DEP profile could be easily matched to that of NGRIP as they looked close to identical. Now it appears that the layer thinning in the EGRIP core is varying but more significant than at the corresponding age in the NGRIP ice core. This makes it more difficult to match up the cores as the finer details of the climate variability are no longer captured in the thinned EGRIP profile. The exciting consequence of the increased thinning is that age increases faster with depth, so that potentially the core will be older in the deepest part than we anticipated last week. Currently, each drilled meter of ice adds another 2-300 years to the age. If our matching to NGRIP is correct, the drilling will most likely reach 100,000 years within a few days. Only a handful of Greenland ice cores have reached this age with well-preserved stratigraphy all the way: GRIP, GISP2, NGRIP, NEEM, and Renland/RECAP. But let’s take one millennium at a time, nothing can be taken for granted where we are now.

What we did today:

1. Drilled 4 ice cores.
2. Logging depth: 2538.39 m. Processing depth: 2528.35 m.
3. Physical properties measurement 2517.35 m.
4. Received Greendrill Twin-Otter / Nordland 610 / C-FTFX with 3 crew.
5. Worked on drill liquid level acoustic Pinger.
6. Worked on borehole camera.
7. Cleared out trench entrances for drift snow.

Weather today: Temperatures have been rising from -34°C last night to -17°C in the evening. Wind 5-12 kt from W and SW.

FL, Anders Svensson