Tagged in PAIS - general 253 downloads
Antarctic and Southern Ocean Future Drilling Workshop
Portland, Oregon, USA
13 - 14 of July 2012
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):
Main questions underpinning future scientific drilling around Antarctica and in the Southern Ocean, and tied to the IODP Science themes, are:
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