What's the age of the ice on Kilimanjaro?

The age of the plateau glaciers on Kilimanjaro’s highest peak, Kibo, is currently debated. While Thompson et al. (2002) regard them as a persistent feature of the Holocene disappearing due to rising 20th century temperatures, Kaser et al. (2010) suggest typical ‘life cycles’ of the ice of only a few hundred years caused by precipitation changes. In order to date Kilimanjaro’s ice with our new radiocarbon method, we collected horizontal ice samples from a 30 m high vertical ice wall of the Northern Ice Field. 24 horizons characterised by different particle contents were selected and two short cores were obtained from each horizon using a battery drill operated by two scientists belayed by top rope. The ice was transported frozen, is now being analysed and first results are expected soon. The expedition was conducted in collaboration with Douglas Hardy, University of Massachusetts, who measured mass balance stakes and serviced the weather station on the Northern Ice Field (Project Website: http://www.geo.umass.edu/climate/kibo.html).

Surface-to-bedrock ice core from Silvretta glacier

From 20 to 25 April 2011 we recovered a 101 meter surface-to-bedrock ice core from Silvretta glacier (46°50’47’’ N, 10°05’79’’ E, 2927 m a.s.l.) in the Swiss Alps. Silvretta glacier is temperate with ice temperatures near the melting point between ca. 10 m below surface and bedrock. Temperate ice contains 0.1% to 2% liquid water, mostly at grain boundaries. The upper 12 m were drilled electromechanically and for the deeper 89 m our new thermal drill was used. The ice core from Silvretta glacier is being analysed in the frame of the SNF-Project „Accelerated release of persistent organic pollutants (POPs) from Alpine glaciers“ in order to investigate the transport of POPs within temperate ice and and quantify their release by melting. This is a collaborative effort, involving scientists from PSI, University of Bern, ETH Zurich, EAWAG, and EMPA.

First ice core from temperate Ewigschneefeld

On 12 September 2010 our team finished ice core drilling at 57 m depth on Ewigschneefeld (46°33’ N, 08°01’ E, 3462 m a.s.l.) in the Swiss Alps. Ewigschneefeld is a temperate glacier, containing a water table at about 21 m depth. The upper 31 m were drilled electromechanically and for the deeper part our new thermal drill was used (www.icedrill.ch). The new drill produced ice cores of excellent quality even in the water-filled borehole. The ice core from Ewigschneefeld is being analysed in the frame of the SNF-Project „Accelerated release of persistent organic pollutants (POPs) from Alpine glaciers“ in order to investigate the transport of POPs within temperate ice and quantify their release by melting.

Drilling at Jungfraujoch