GISP - The Greenland Ice Sheet Program

by Mike Savage
The Greenland Ice Sheet Program (GISP 2) culminated in 1993 when the last section of an ice core that penetrated through the full depth of the Ice Sheet was extracted.  I  was privileged to be there, working for Ken Taylor of the Desert Research Institute and assisting in the analysis of the core. 

  Drill Dome at GISP 2 Camp

A 3000 meter ice core was extracted from the Greenland Ice Sheet using this specialized drilling rig

In the early 1990's, scientists established a drilling camp at the apex of the Greenland Ice Sheet, with the goal of extracting an ice core through the complete depth of the of the ice, more than 3000 meters.  Several summer drilling seasons culminated in 1993 when the drill struck bedrock at the bottom of the ice, completing the extraction of the world's longest continuous ice core record for climate studies.
Analysis of the data revealed the unexpected volatility of past climate changes.  Prior to this analysis, the consensus among climate scientists favored a theory of gradual transistion between climatic regimes.  But the Greenland core data showed clear evidence of abrupt climate shifts taking place over only a few years rather than decades.  The implications for climate change during the present are worrisome.

Mike Savage measuring the resistivity of the ice core for climatatic analysis

Several techniques were employed in order to extract the climate signal from the ice core, including chemical, stratigraphic and oxygen isotope analysis.  Dr. Kendrick Taylor of the Desert Research Institute was responsible for the resistivity analysis.  This methodology is premised on the changing resistivity of the ice as a function of the gases and particulates present at the time when snow was precipitated and became entrained within the Ice Cap.  This technique produces a very high resolution (seasonal) signal that is used to deduce climatic conditions during the past.

The final cores extracted from the very bottom of the Ice Sheet

As the drill neared the bottom it began to bring up "silty ice" that had mud and small pebbles entrained within.  After about 30 meters of silty ice had been extracted, the drill encountered bedrock and was able to bore into the rock and bring up samples, completed a multiyear project involving several Universities from around the world and an enormous logistical effort in establishing and maintaining a camp in such an extreme environment.

Ski-equipped C-130 Hercules arriving at Sonderstromfiord