SCIENCE

Map of Antarctica WAIS (West Antarctic Ice Sheet) Divide is a United States deep ice coring project in West Antarctica funded by the National Science Foundation (NSF). WAIS Divide's goal is to examine the last ~100,000 years of Earth's climate history by drilling and recovering a deep ice core from the ice divide in central West Antarctica.

Ice core science has dramatically advanced our understanding of how the Earth's climate has changed in the past. Ice cores collected from Greenland have revolutionized our notion of climate variability during the past 100,000 years. The WAIS Divide ice core will provide the first Southern Hemisphere climate and greenhouse gas records of comparable time resolution and duration to the Greenland ice cores enabling detailed comparison of environmental conditions between the northern and southern hemispheres, and the study of greenhouse gas concentrations in the paleo-atmosphere, with a greater level of detail than previously possible. The WAIS Divide ice core will also be used to test models of WAIS history and stability, and to investigate the biological signals contained in deep Antarctic ice cores.

What makes the WAIS Divide ice core special?

  • The most significant and unique characteristic of the WAIS Divide project will be the development of climate records with an absolute, annual-layer-counted chronology for the most recent ~40,000 years.
  • Due to the high snowfall rate at WAIS Divide, the ice core record will have a very small offset between the ages of the ice and the air (i.e., gases) trapped in the ice. Because of this small age difference between the gases and the enclosing ice, a decadal-precision climate chronology relative to the Greenland ice cores is expected.
  • The combination of high-time resolution and the small age offset will allow us to study interactions between climate variations and atmospheric composition with a level of detail previously not possible in deep long Antarctic ice core records.
  • Unlike the Greenland ice cores, an excellent atmospheric CO2 record is expected to be obtained from the WAIS Divide ice core since Antarctic ice has an order of magnitude less dust than Greenland ice.
  • Many other gases (both greenhouse and non-greenhouse) and their isotopes will be measured at unprecedented precision and resolution.

What is an ice divide?
An ice divide is analogous to a watershed divide. An ice sheet divide separates opposing flow directions of ice on an ice sheet.

Why do we want to drill near an ice divide?
Snow and ice that accumulates on an ice divide moves vertically downward with time. As you move laterally off of an ice divide the ice increasingly moves horizontally. Irregularities in the bedrock below the ice sheet can cause horizontally moving layers of ice to bend and fold thus disturbing the internal layering of the ice. Ice coring is typically made on top of ice divides to minimize these potential interferences in the stratigraphic record caused by horizontal ice movement. The WAIS Divide drill site is actually ~24 kilometers downslope of the current ice divide because ice divides can migrate over time. Drilling slightly off of the current ice divide helps ensure that no divide migration has compromised the stratigraphy of the ice core record.

Why WAIS Divide?
The WAIS Divide site was chosen because it is an almost exact analogue to GISP2 in Greenland in terms of accumulation rate, temperature, gas age-ice age difference, and distance from the ice divide.

Main science objectives:

  • Develop the most detailed record of greenhouse gases possible for the last 100,000 years
  • Determine if the climate changes that occurred during the last 100,000 years were initiated by changes in the northern or southern hemisphere
  • Investigate the past and future stability of the West Antarctic Ice Sheet
  • Investigate the biology of deep ice