pdf Antarctic and Southern Ocean Future Drilling Workshop 2012

Antarctic and Southern Ocean Future Drilling Workshop

Portland, Oregon, USA

13 - 14 of July 2012

Summary:

Valuable insights into the future sensitivity of the Antarctic cryosphere to atmospheric and oceanic warming can be gained from long-term geologic records of how it changed during past warm periods. While paleoclimate records spanning hundreds of thousands of years have been obtained from Antarctic ice cores, continental outcrops and margin to deep ocean sediments cores provide records of contemporaneous changes in ice sheet extent and oceanographic conditions, that extend farther back in time, including periods with atmospheric CO₂ levels and temperatures similar to those that are likely to be reached in the next 100 to 200 years.

Based on the existing data and the current knowledge, successful projects with a multi-leg, multi-platform approach can be developed (e.g. transects involving a combination of ANDRILL, seabed drilling and JOIDES Resolution sites). The purpose of the workshop, held in Portland (Oregon, USA) on 13 and 14 of July 2012, was to stimulate new Antarctic and Southern Ocean drilling proposals and ensure coordination among existing ones, so that regional, scientific objectives are tackled through a unified approach. The workshop held before the SCAR Open Science Conference 2012, with the financial support of the SCAR/ACE program, was attended by 50 participants (annex 1) from all over the world, with a wide range of geoscience skills, technology expertise and project management experience. It offered an ideal opportunity to hold open discussions to guide and stimulate concerted international action to ensure a robust plan for Antarctic scientific drilling during the next phase of IODP.

The strategy followed that of the IODP Science Plan in addressing outstanding scientific questions by drilling several depth and latitudinal transects in different sectors of the East and West Antarctic margin, where the ice sheet is grounded below sea level and is considered to be unstable. These questions are also relevant to three of the IODP Science Themes (Theme 1 in particular):

1. Climate and Ocean Change: Reading the past informing the future.
   • Challenge 1: How does Earth’s climate system respond to elevated levels of atmospheric pCO2?
   • Challenge 2: How do ice sheets and sea level respond to a warming climate?
   • Challenge 3: What controls regional patterns of precipitation, such as those associated with Monsoons or El Niño? (in areas where ultra-high resolution Holocene records exist – e.g., Wilkes Land, Prydz Bay, Antarctic Peninsula e.g. Palmer Deep, Maxwell Bay)
2. Earth Connections: Deep-processes and their impact on Earth’s subsurface environment
3. Biosphere Frontiers: Deep life, biodiversity, and environmental forcing of ecosystems

Main questions underpinning future scientific drilling around Antarctica and in the Southern Ocean, and tied to the IODP Science themes, are:

1. How will the Antarctic Ice Sheets respond to elevated temperatures and atmospheric pCO2? What is the contribution of Antarctic ice to past and future sea level changes in terms of rate and magnitude?
2. What did a “greenhouse world” look like in Antarctica? Can Antarctica sustain any ice sheets when the atmosphere is above 1000 ppm CO2?
3. What were the patterns, causes, and consequences of Gondwana breakup (recorded in large igneous provinces and continental fragments of the Southern Ocean)? What was the timing of rifting and subsidence controlling the opening of ocean gateways and the initiation of the circumpolar current system?

The ANDRILL program has demonstrated the ability to recover >98% of the drilled sediments at continental shelf sites. In addition, despite the low recovery from drilling continental shelf sediments at some sites, drilling at others on DSDP 28, ODP 188 and the recent IODP Expedition 318 of the Wilkes Land margin has shown that ship-based riser-less drilling can achieve good recovery (60-100%) from glacially-influenced continental rise sediments. In order to maximize recovery it is essential that sufficient and good-quality site surveys are carried out, that the most appropriate drilling tools are used with regard to the expected sedimentary facies, that clear weather/ice contingencies and accurate drilling time are estimated, and that an adequate number of alternate sites are planned (i.e. operational flexibility and good site surveys). Technological advances, such as drilling from a stable platform (e.g. the ANDRILL deep drilling and the MeBo shallow drilling) and a riser system (employed by Chikyu, ANDRILL, and the petroleum industry), could allow greater improvements to the recovery from the continental shelf.

Improved paleonvironmental and dating methods have been developed through the ANDRILL project and by drilling more continuous sections from continental rise sediment drifts. In some cases the improved chronology allows insights into ice sheet dynamics at orbital scale through Miocene and Pliocene times. It is also important to recognize that there are still large time intervals and regions around Antarctica in which no data exist, and even 20-30% recovery from these can still significantly advance our understanding of ice sheet history

Workshop Conveners:

• Laura De Santis (geophysics) - Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS), Trieste, Italy This email address is being protected from spambots. You need JavaScript enabled to view it.
• Karsten Gohl (geophysics) – Alfred Wegener Institute, (AWI), Bremerhaven, Germany This email address is being protected from spambots. You need JavaScript enabled to view it.
• Rob Larter (geophysics) – British Antarctic Survey (BAS), UK This email address is being protected from spambots. You need JavaScript enabled to view it.
• Carlota Escutia (geophysics and paleoceanography, ESSAC chair and SCAR/ACE leader) – University of Granada (Spain) This email address is being protected from spambots. You need JavaScript enabled to view it.
• Minoru Ikehara (paleoceanography) Center for Advanced Marine Core Research, Kochi University (Kochi Core Center : KCC), Nankoku Japan This email address is being protected from spambots. You need JavaScript enabled to view it.
• Jongkuk Hong (geophysics) , Korean Polar Research Institute KOPRI, Korea. This email address is being protected from spambots. You need JavaScript enabled to view it.
• Tim Naish (paleoceanography) - Antarctic Research Centre Victoria University of Wellington, NZ. This email address is being protected from spambots. You need JavaScript enabled to view it.
• Peter Barrett (paleoceanography) Antarctic Research Centre Victoria University of Wellington, NZ. This email address is being protected from spambots. You need JavaScript enabled to view it.
• Frank Rack (Executive Director ANDRILL Science Management Office) University of Nebraska - Lincoln, USA This email address is being protected from spambots. You need JavaScript enabled to view it.
• Julia Smith Wellner (paleoceanography) University of Houston, USA This email address is being protected from spambots. You need JavaScript enabled to view it.

Contact person: Laura De Santis, OGS, Trieste, Italy. This email address is being protected from spambots. You need JavaScript enabled to view it.