RESEARCH TEAM GRANTS IN ANTARCTIC SCIENCE 2005 FINAL REPORT I. PROJECT PRESENTATION PROJECT TITLE CODE Stability and recent behavior of glaciers in the Antarctic Peninsula - the interactions with ice shelves ARTG-02 PROJECT DIRECTOR SIGNATURE Anja Wendt CONTACT INFORMATION [email protected] - (63) 234 531 - Arturo Prat 514, Valdivia, Región De Los Ríos MAIN INSTITUTION CECS PERIOD INFORMED 2007 - 2010 1 Researchers’ information 1.MAIN RESEARCHER (Complete Name) SIGNATURE Anja Wendt WORKING ADDRESS PHONES EMAIL Av. Arturo Prat 514, Valdivia 63-234585 [email protected] 2.MAIN RESEARCHER (Complete Name) SIGNATURE Francisca Bown WORKING ADDRESS PHONES EMAIL Av. Arturo Prat 514, Valdivia 63-234564 [email protected] 3. MAIN RESEARCHER (Complete Name) SIGNATURE Rodrigo Zamora WORKING ADDRESS PHONES EMAIL Av. Arturo Prat 514, Valdivia 63-234529 [email protected] 1.ASSOCIATED RESEARCHER (Complete Name) SIGNATURE Jorge Carrasco Cerda WORKING ADDRESS PHONES EMAIL Avda. Portales 3450, Estación 2-436 4519 [email protected] Central, Santiago. 2.ASSOCIATED RESEARCHER (Complete Name) SIGNATURE Juan Quintana WORKING ADDRESS PHONES EMAIL Avda. Portales 3450, Estación 2-436 4531 [email protected] Central, Santiago. 3.ASSOCIATED RESEARCHER (Complete Name) SIGNATURE Gino Casassa WORKING ADDRESS PHONES EMAIL Av. Arturo Prat 514, Valdivia 63-234540 [email protected] 4.ASSOCIATED RESEARCHER (Complete Name) SIGNATURE Andrés Rivera WORKING ADDRESS PHONES EMAIL Av. Arturo Prat 514, Valdivia 63-234543 [email protected] 3 5.ASSOCIATED RESEARCHER (Complete Name) SIGNATURE José Andrés Uribe WORKING ADDRESS PHONES EMAIL Av. Arturo Prat 514, Valdivia 63-234544 [email protected] 6.ASSOCIATED RESEARCHER (Complete Name) SIGNATURE Claudio Bravo . WORKING ADDRESS PHONES EMAIL Av. Arturo Prat 514, Valdivia 63-234538 [email protected] 4 II. EXECUTIVE SUMMARY This section should have a maximum of 5 pages long. Summarize the most relevant achievements of the ENTIRE PERIOD indicating: 1) Those explicitly related to the research activities and outcomes, 2) Activities and possible projections of international collaboration, 3) Results of the training of postgraduate students and young researchers, 4) The possible links to other national researchers either as groups and centers or, as individual researchers 5) Outputs of dissemination activities to the scientific community and outreach to non-specialized public. 6) Others either unexpected and/or that you consider significant Please consider that the contents of this section will be published in CONICYT web site and/or reports that may be eventually printed and distributed. The Antarctic Ring project ARTG‐02 was realized from 2007 to 2010, period in which we deployed a multiscale/multiapproach working plan characterized by a strong field component in different locations of the Antarctic Peninsula (AP). The project focused on the Wordie Ice Shelf/Fleming Glacier system due to its key location in a highly‐dynamic area. The AP is indeed a climatic hot spot, which forms part of the world’s largest ice reservoir and has a significant atmospheric and oceanographic influence on the rest of the globe. Therefore the cryospheric changes occurring in that region are of fundamental importance. So far, ice shelf break‐off leading to inland glacier retreat has been well reported for the northern portion of the AP. The former Wordie Ice Shelf, located to the west of the AP, was really the first ice shelf reported to collapse in the AP. It suffered a large break‐up by the end of the 1980s, and although it was located well to the south (69°S) of the rest of the collapsing ice shelves in the AP, its continued disintegration along the past 21 years has led to its virtual disappearance by 2010. Union Glacier (80°S) draining into Ronne Ice Shelf, West Antarctica, was also studied as part of this project, since it represents a contrasting case study of a theoretically stable glacier flowing into a still undisturbed ice shelf in a region of inner Antarctica which has not yet experienced significant warming. The main aim of the project was to characterize the glaciological setting of Fleming Glacier, the largest glacier in Wordie Bay, to investigate its response to the loss of its buttressing ice shelf. Surface topography data of this glacier were available from previous airborne campaigns of CECS with international collaborators, a satellite altimetry mission 5 and our own airborne survey system, allowing determination of the most recent ice elevation changes of Fleming Glacier. These measurements were estimated as highly‐ precise which is demonstrated by confident analysis of data sets biases. In the period between 2004 and 2008 a clear thinning is identified which decreases from about 4 m per year at the ice front to a value of 0.7 m per year at the highest part of the surveyed profile (1070 m a.s.l.). This altitudinal pattern is similarly found between 2002‐2008 and 2004‐2008, suggesting a decadal trend. Ten months of GPS data collected in 2009 provide an independent estimation of height changes and support these findings. Likewise, ice flow velocities from different dates were compared to provide an insight into ice flow changes. Our GPS‐derived velocities agree with results from the 1990s and both confirm higher ice flow velocities than in the 1970s. Optical and radar satellite data acquired between 1989 and 2010 revealed an acceleration of the fast–moving glacier terminus, which attained a maximum velocity of about 2800 m/yr in 2010. In summary, in‐ situ and remote sensing tools revealed that Fleming Glacier has accelerated 30‐50% in comparison to the oldest available data in the 1970, giving indication of prevailing disequilibrium in response to the loss of the Wordie Ice Shelf. Conversely, based on our measurements we conclude that Union Glacier, remains in a steady‐state due to the conditions of Ronne Ice Shelf which seems non susceptible of disintegration in the near future. Mean velocities at Union Glacier are two orders of magnitude lower than in Fleming Glacier. Estimation of ice volumetric discharges at the grounding line were performed based on the resulting velocity data in combination with ice thickness data from different pre‐ existing and new sources at flux gates crossing the glaciers. At present day, the ice volume flux at Fleming Glacier is estimated between 8 and 10 cubic kilometre per year, suggesting a significant increment since 1989. Accordingly, the contribution of this region to sea level rise must have also increased. Comparison of ice discharge with snow accumulation allows to estimate a mass imbalance for Fleming Glacier of 83 to 130% in 1989 and more than 160% imbalance in 2010. When converted to Sea Level Equivalent (SLE), the current contribution can be estimated to ~ 0.012‐0.017 mm/yr, which has doubled in comparison to 1989. Long‐term climate variability along the Antarctic Peninsula shows distinctive patterns which overall, follow the tendency of atmospheric warming and increased precipitation. Among the most reliable is the large increase in minimum temperatures mainly in winter, thus reducing the diurnal thermal oscillation, as well as the lower frequency of cold nights. Annual precipitation shows strong interannual variability with increasing frequency of days with high precipitation. As for the type of precipitation, in the case of Eduardo Frei station, snowfall between 1970 and 2008 was detected to decrease 6 concomitant to the opposite trend for rain. This finding is consistent with temperature changes previously described. At a local and short‐term scale, there is a good characterization of the meteorology of the southern AP using the Fleming Automatic Weather Station (69°32’S, 66°1’W, 1057 m a.s.l) that operated between December 2007 and December 2008. The observed precipitation in AP meteorological stations is closely linked to the frontal activity and circulation patterns associated to the so called Antarctic Oscillation. The link of Antarctic precipitation to the sea surface temperatures (SST) is also strong and involves the whole Southern Pacific Ocean. Accordingly, El Niño Southern Oscillation (ENSO), having an utmost worldwide meteorological impact, does also affect atmospheric circulation in the surroundings of the study area. In particular, ENSO produces blocking‐ high pressure cells on the western side under the El Niño phase and negative precipitation anomalies prevail. The ultimate cause of atmospheric warming can also be found on large scale phenomena such as the positive trend of the Antarctic Oscillation Index (AAO) during the last decades due to enhanced westerlies which bring the warmer maritime air over the AP. A strong international collaboration existed throughout the project. The interaction with Dr. Konrad Steffen, leader of the NSF‐funded project ʺStability of Larsen C Ice Shelf in a warming climateʺ resulted in joint fieldwork at Larsen C and a 5 month visit of a M.Sc. Student to University of Colorado at Boulder as part of his thesis work. The remote location and methods deployed at Fleming Glacier implied complex logistics supported by a number of institutions; British Antarctic Survey (BAS), Instituto Antártico Chileno (INACh) and Chilean Air Force (FACh). At Union Glacier there is a well established cooperation with the private company Antarctic Logistics and Expeditions (ALE) which has resulted in fruitful work during the last three seasons. In addition, the project benefited from other previous alliances of CECS which allowed the availability of prominent airborne and geophysical data in the AP. Several consulting from foreign experts, short visits, seminars, presentations at international congresses and staff meetings were also a key input into the different stages of the project, improving the scientific approaches and fulfillment of research objectives. Overall, this resulted in three high‐ quality publications as the outcome of the project. In 2010, two International Conferences were organized by CECS with the partial financial support of the Ring project. The Glaciological Conference ʺIce and Climate Change: A View from the Southʺ (VICC 2010) was held in February when a special Antarctic session was the opportunity to bring the most recent research to discussion.