Ice core drilling at Whitehall Glacier (WHG) and Mt Erebus Saddle (MES)

The scientific goal of the NZ ice core programme is to improve our understanding of the major Southern Hemisphere climate drivers causing high frequency climate variability. These are in particular the El Niño Southern Oscillation (ENSO), the Antarctic Oscillation, and the Antarctic Circumpolar Wave, as well as drivers and feedback mechanisms causing abrupt climate change. These climate drivers operate on relatively short time scales (sub-decadal) but also potentially respond to longer term forcing (centennial to millennial). It is therefore important to obtain high resolution (sub-annual) records that can reliably capture the high frequency variability of these drivers from sites that are particularly sensitive to their influence, and at the same time providing a long enough record to investigate superimposed longer-term trends. ITASE focuses on the last 200 years and where possible longer.

We have identified key locations at low elevation, coastal sites that are particularly climate sensitive, as they capture tropospheric climate variability and in general have a higher snow accumulation rate than sites from the Antarctic interior. This makes these sites ideal when investigating abrupt climate change. For this reason, the International Partnership of Ice Coring Sciences (IPICS) has identified an array of 2000-year long records from especially coastal sites as one of four priorities for ice core research in the next 20 years. Currently only NZ and Australia have worked on coastal sites.

For this field season our objective was to recover two intermediate depth ice cores from WHG and MES.

WHG is a small, East Antarctic Ice Sheet independent ice mass with an ice divide at 500 above sea level, just 12km of the coast. Due to its coastal, low elevation characteristics it is ideal for our NZ ITASE objective. In addition to this, an ideal site should satisfy the following: a) consistent annual precipitation (even if seasonal), b) limited summer melt c) limited wind erosion or snow accumulation through wind drift, d) a long enough record (for our purposes at least 200 years but preferably ≥ 2000 years), and e) undisturbed ice flow and smooth bedrock topography.

MES has an extremely high accumulation rates, exceeding by one order of magnitude the regional average. The drill site is located at an ice divide at 1600 above sea level, just 20km of the coast.