Drilling down to the Earth’s oldest ice
A recent drilling campaign conducted in Antarctica as part of the EU-funded Beyond EPICA project has achieved an important climate science milestone. It reached a depth of 2 800 metres into the ice, where the ice sheet meets the bedrock. The ice extracted from the remote Little Dome C site could provide scientists with vital information on how Earth’s climate has evolved across the ages. Besides preserving a unique record of our planet’s climate history, the extracted ice will also offer valuable insight into atmospheric temperatures and pristine samples of old air with greenhouse gases from the period between 900 000 and 1.2 million years ago. Known as the Mid-Pleistocene Transition, this period saw the slowing down of glacial cycles from 41 000-year to 100 000-year intervals. “We have marked a historic moment for climate and environmental science,” remarks Carlo Barbante, professor at Beyond EPICA project partner Ca’ Foscari University of Venice, Italy, in a ‘Eurasia Review’ news item. “This is the longest continuous record of our past climate from an ice core, and it can reveal the interlink between the carbon cycle and temperature of our planet.” According to Julien Westhoff, chief scientist in the field from Danish project partner University of Copenhagen, preliminary analyses recorded at the site strongly indicate that “the uppermost 2,480 meters contain a climate record that goes back to 1.2 million years in a high-resolution record where up to 13,000 years are compressed into one meter of ice.” The right drilling location at Little Dome C was identified using cutting-edge radio echo sounding technologies and ice flow modelling. “Impressively, we found the record that goes from 0.8 to 1.2 million years ago, exactly where it was predicted to be, in the depth range between 2426 and 2490 meters, extending our previous twenty-year-old EPICA ice core record,” notes Frank Wilhelms of German project partner Alfred Wegener Institute.
Beyond 1.2 million years
Below the ice preserving the 1.2-million-year record, the lowest 210 metres of the ice core above the bedrock consist of heavily deformed old ice of unknown origin, believed to be mixed or refrozen. Advanced analysis of this ice could shed light on the behaviour of refrozen ice under the Antarctic ice sheet and offer insight into East Antarctica’s glaciation history. “The precious ice cores extracted during this campaign will be transported back to Europe on board the icebreaker Laura Bassi, maintaining the -50°C cold chain, a significant challenge for the logistics of the project,” states Gianluca Bianchi Fasani, senior researcher at project partner ENEA-UTA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development – Antarctica Technical Unit). Once the ice cores arrive in Europe, the Beyond EPICA (Beyond EPICA Oldest Ice Core: 1,5 Myr of greenhouse gas – climate feedbacks) researchers will analyse the ice samples to learn about our planet’s climate and atmospheric history and date the underlying rocks to discover when this part of Antarctica was free of ice for the last time. For more information, please see: Beyond EPICA project website
Keywords
Beyond EPICA, Antarctica, climate, drilling, ice, ice core
