Researchers in INSTAAR's Stable Isotope Lab are part of an ambitious deep ice-coring project in West Antarctica, sponsored by NSF, for studies of paleoclimate, ice sheet history, and cryobiology. This multi-year project has been collecting a deep ice core from the West Antarctic Ice Sheet (WAIS) ice flow divide and integrating approximately 40 separate but synergistic projects with over 100 people to analyze the ice and interpret the records.
The project as been ongoing since the WAIS field site was established in 2005, and during 5 subsequent (short) austral summer field seasons of drilling, over 4,405 meters of ice have been recovered. The cores are allowing scientists from many different universities and research groups to apply their individual measurement expertise to extract the highest resolution climate record ever created for a polar ice core. The WAIS Divide climate records have an absolute, annual-layer-counted chronology for the most recent ~40,000 years. It was expected that the lower temporal resolution records would extend beyond ~100,000 years before present, but it was a big surprise to many that the oldest ice at the bottom of this core was less than 70,000 years old. Basal melting has played a role in removing ice from the bottom of the ice core. This high-resolution climate reconstruction that is being created from West Antarctica along with similar records from Greenland ice (eg. NEEM ice core) will enable comparison of environmental conditions between the northern and southern hemispheres over the last 60,000 years. The study will also provide a record of key greenhouse gas concentrations in the paleo-atmosphere, with a greater level of detail than previously possible.
Here at INSTAAR, Jim White, Bruce Vaughn and Valerie Morris have developed a new method that incorporates a continuous ice-core melter and a Picarro Cavity Ring Down Laser Spectrometer to provide what is now the world's highest-resolution stable isotope record from any ice core. Previous methods of laboriously cutting small samples of ice for individual analysis on mass spectrometers yielded approximately 24 to 50 isotopic samples per meter resolution. The new method yields over 2,400 isotopic values per meter, allowing the capture of virtually any isotopic signal that is preserved in the ice to be measured.
Some fun facts about WAIS Divide:
- Average temperature: -31°C
- Ice thickness: 3,465 meters
- Surface elevation: 1,759 meters
- Summer population: ~ 45 people
- Winter population: Zero
Read more about it: the WAIS media guide from the 2011-2012 field season tells why we're at WAIS, describes the many research projects that are joined in the endeavor, and shows how the drill works.