Pettit/0732738 Gordon/0732651 Truffer/0732602 Mosley-Thompson/0732655
Like no other region on Earth, the northern Antarctic Peninsula represents a spectacular natural laboratory of climate change and provides the opportunity to study the record of past climate and ecological shifts alongside the present-day changes in one of the most rapidly warming regions on Earth. This award supports the cryospheric and oceano-graphic components of an integrated multi-disciplinary program to address these rapid and fundamental changes now taking place in Antarctic Peninsula (AP). By making use of a marine research platform (the RV NB Palmer and on-board helicopters) and additional logistical support from the Argentine Antarctic program, the project will bring glaciologists, oceanographers, marine geologists and biologists together, working collaboratively to address fundamentally interdisciplinary questions regarding climate change. The project will include gathering a new, high-resolution paleoclimate record from the Bruce Plateau of Graham Land, and using it to compare Holocene- and possibly glacial-epoch climate to the modern period; investigating the stability of the remaining Larsen Ice Shelf and rapid post-breakup glacier response ? in particular, the roles of surface melt and ice-ocean interactions in the speed-up and retreat; observing the contribution of, and response of, oceanographic systems to ice shelf disintegration and ice-glacier interactions. Helicopter support on board will allow access to a wide range of glacial and geological areas of interest adjacent to the Larsen embayment. At these locations, long-term in situ glacial monitoring, isostatic uplift, and ice flow GPS sites will be established, and high-resolution ice core records will be obtained using previously tested lightweight drilling equipment. Long-term monitoring of deep water outflow will, for the first time, be integrated into changes in ice shelf extent and thickness, bottom water formation, and multi-level circulation by linking near-source observations to distal sites of concentrated outflow. The broader impacts of this international, multidisciplinary effort are that it will significantly advance our understanding of linkages amongst the earth's systems in the Polar Regions, and are proposed with international participation (UK, Spain, Belgium, Germany and Argentina) and interdisciplinary engagement in the true spirit of the International Polar Year (IPY). It will also provide a means of engaging and educating the public in virtually all aspects of polar science and the effects of ongoing climate change. The research team has a long record of involving undergraduates in research, educating high-performing graduate students, and providing innovative and engaging outreach products to the K-12 education and public media forums. Moreover, forging the new links both in science and international Antarctic programs will provide a continuing legacy, beyond IPY, of improved understanding and cooperation in Antarctica.
Antarctica's Peninsula area (south of South America) is one of the most rapidly changing areas on Earth, and provides a kind of 'natual laboratory' for understanding how other, larger areas of Antarctica might evolve in the coming decades. In 1995, and again in 2002, the region saw large rapid disintegrations of several thick plates of floating ice that had been thought to be permanent parts of the ice sheet. The disintegrations were largely a result of recent climate warming, resulting from changes in wind patterns driven by both ozone loss in the high atmosphere and the general warming of the air due to greenhouse gases. Following the loss of the large thick floating plates of ice ('ice shelves') the glaciers that had been flowing into the shelves rapidly accelerated. This showed that climate change can have a rapid and highly non-linear impact on sea level rise, and showed the science community completely new processes previously unseen in glaciology. The Larsen Ice Shelf System, Antarctica (LARISSA) project was designed to study the full range of responses, in ecosystems, marine geology, climate, and glaciology, to this sudden change in the environment of coastal Antarctica. As a back-up, we also planned to study the adjacent coasts of the Antarctic Peninsula to look at longer-term effects of changes (areas that had been retreating for the past few centuries). Here we discuss the major glaciological results. An ice core was collected at the ice cap ridge crest of the Peninsula, and the site location was selected by a 10-day survey of the ridge area using ground-based radars, GPS, and remote sensing data. A 447-m ice core, spanning approximately 2000 years and more (many years are compressed in the lowest ice layer) was collected and provided a wealth of data on recent climate changes (discussed elsewhere). For glaciology, the study has resulted in an analysis of a full flowline crossing the Peninsula by combining many data sets (Pettit et al., 2015 in prep.; Figure 1). The major result is that the western side (the windward side, with very high snowfall) and eastern side (lee side, very low snowfall, colder) have very different ice flow styles. Morevover, the ridge crest location is very responsive to changes in temperature and snowfall rates, and can move rapidly (km per century) to the east or west depending on conditions. A series of advanced sensor stations (Automated Met-Ice-Geophysics Observing Systems, AMIGOS) were set up in the region, as well as precision GPS stations. These stations had multiple research goals: to understand how weather responsed to changes in broader climate patterns, to observe chagnes in ice flow speed, to monitor snow temperature and surface melting, and to take digital pictures of the evolution of the surface structures, melt ponds, and calving events. Data from these stations supported ecosystem studies of weather impacts on primary production (plankton growth) and the frequency of certain wind events (chinook or foen winds; Cape et al., 2014 in prep.), and have provided a record of crevassing changes within a remnant section of ice shelf as well as panoramic image series of the evolving ice front at Scar Inlet (Figure 2). Two major studies are underway using the AMIGOS data and both remote sensing records and oceanographic measurements. One is a study of the evolution of the remaining area of the Larsen B Ice Shelf, the Scar Inlet Ice Shelf. The shelf has undergone significant changes since 2002 and is now very unstable. The other will look at the earliest records of ice strucure in satellite images, and at sea ice trends for the ocean east of the ice shelves. The hypothesis is that reduced sea ice cover in spring-summer led to increased wind traction on the ocean surface, changing circulation on the both the surface waters and deeper layers. This may have drawn cold but above-freezing water into the Larsen B sub-shelf area in the 1980s and early 1990s, initiating the weakening of the shelf that facilitated disintegration by surface melting.
