A View Beneath Antarctic IceThe Importance of Communicating Environmental Change to the PublicGlobal warming is occurring and the Antarctic ice is melting. Sea level is rising and the impact on coastal areas and cities like Boston, NY and London will be evident within our lifetime. Antarctica hosts two major ice sheets, which hold 90% of the world's fresh water. Together, these ice sheets are a key component of the world's climatic system and have a major influence on global sea levels. Indeed, if they melted completely, sea level would be raised by about 65 meters. The West Antarctic Ice Sheet (WAIS) is particularly vulnerable to warming trends because large sections of it are not grounded on continental rocks, but extend out over the ocean. The more than three kilometers-thick ice within the Amundsen Sea Embayment is recognized as the part of the unstable WAIS with the greatest potential for collapse as a result of climate warming. Although the Amundsen Sea Embayment has one of the highest rates of snow accumulation in Antarctica, the ice within the Embayment is melting, thinning, and retreating rapidly.like Pine Island and Thwaites Glaciers, two of the fastest flowing Antarctic ice streams within the Amundsen Sea Embayment-, produce massive and rapid discharges of ice into the ocean, and could lead to significant global sea level rise during the next 100 years. Much of the evidence documenting changes to the Antarctica ice comes from coordinated research programs, such as the recent University of Texas Institute for Geophysics (UTIG)/ British Antarctic Survey (BAS) airborne geophysical survey of the Amundsen Sea Embayment, Antarctica (referred to as AGASEA)-one of the largest field projects the continent has ever witnessed. UTIG Research Associate Jack Holt and BAS scientist David Vaughn led the AGASEA field team comprising 15 U.S. and six U.K. scientists, technicians, and students. AGASEA acquired geophysical data for the drainage basins of the Pine Island and Thwaites Glaciers-a 290,000-square-kilometer area (roughly the size of New Mexico) that is not well understood due to its notoriously poor weather and remote location. The Pine Island and Thwaites Glaciers, two of the fastest-flowing glaciers in Antarctica, are of particular concern because satellite studies over the last few years show that the former is thinning at a rate of up to 6 meters per year and that the Thwaites Glacier thinned 25 meters between 1991 and 2001. To carry out AGASEA, two remote field camps were constructed and maintained-an endeavor that required forty flights by U.S. Air Force LC-130 Hercules aircraft from McMurdo Station, the U.S. Antarctic Program's logistical center. The LC-130 aircraft are the largest ski-equipped planes in the world. UTIG's field party and BAS scientists occupied and worked from the two field camps and flew aircraft filled with highly sophisticated geophysical instrumentation capable of operating in the extreme Antarctic environment. The two groups focused data collection efforts in different areas of the survey area to maximize coverage. The UTIG group configured a ski-equipped DeHavilland Twin Otter aircraft with a laser altimeter, a gravimeter, a magnetometer, and a powerful ice-penetrating radar sounder. Once established in the deep field at camps specially built for AGASEA, the UTIG and BAS teams conducted numerous survey flights each day, operating around the clock with multiple shifts in order to take advantage of good weather periods and the limited Antarctic field season. UTIG and BAS together flew 107 flights during the 2004-2005 field season to collect 60,000 line kilometers of data for AGASEA. Laser altimetry data provided accurate measurements of the present surface elevation. Ice-penetrating radar provided images of ice layers and the sub-ice topography many kilometers below the ice surface to help the science team understand how historical snow accumulation rates and annual precipitation affect glacial flow and the overall balance of the WAIS. Gravity and magnetic data reveal tectonic elements, such as faulting and volcanism, which contribute heat to the system and influence flow of overlying glaciers. The human effort required to acquire useful geophysical data in such a remote region of Antarctica is enormous. However, the geophysical results obtained from the Amundsen Sea Embayment are a uniquely important resource for the entire scientific community. "Results from AGASEA provide the information needed to model future ice sheet behavior and potential effects of climate change," said Holt. "They will also be used to establish a benchmark for future satellite studies that will record the same information, but with less precision and at a lower resolution. These results allow us to understand what Antarctica has in store for us in terms of global climate and sea-level change." Fresh from Antarctica, Holt joins fellow BAS scientist, and a pair of award-winning environmental reporters for a session entitled "From Antarctica to India-Communicating Environmental Change" at the American Association for the Advancement of Science (AAAS) Annual Meeting in Washington DC, February 18, 2005. The AGASEA team's ability to image beneath the ice and determine the factors responsible for the melting and thinning of the WAIS gives them a unique perspective on environmental change and the challenges that scientists face in conveying this understanding to the public. Issues of time and scale, for example pose particular challenges. Only in this region of Antarctica are major changes known to occur within a human lifetime. "It is difficult for scientists to communicate changes that are occurring to ice sheets to the general public and decision makers. By imaging the base of the ice, we can translate the rates of ice melting into images that ordinary people can understand", said UTIG scientist and AGASEA team member David Morse. The UTIG AGASEA project is funded by The U.S. National Science Foundation's Office of Polar Programs. The University of Texas Institute for Geophysics (UTIG) is known internationally as a leading academic research group in geology and geophysics. Founded in 1972, it is a part of the John A. and Katherine G. Jackson School of Geosciences at The University of Texas at Austin. UTIG has been in the vanguard when it comes to studying the WAIS, and in fact acquired all the airborne geophysical data for NSF-sponsored US investigators for more than a decade. By Kathy Ellins and Marcy Davis LINKS CONTACTS Dr. John (Jack) Holt, The University of Texas at Austin, Institute for Geophysics (UTIG). Telephone: 512-471-0487. E-mail: jack@ig.utexas.edu; Dr. David Morse, UTIG. Telephone: 512-471-0341. E-mail: morse@ig.utexas.edu; Dr. Donald Blankenship, UTIG. Telephone: 512-471-0489. E-mail: blank@ig.utexas.edu. |