Contact: Media contact: Nick Houtman, Dept. of Public Affairs, 207-581-3777
ORONO, Maine — University of Maine scientists will give presentations about the sun’s influence on global climate, thinning of the Earth’s crust and volcanic dust in Antarctic ice at one of the world’s largest annual gatherings of geophysicists this month. Researchers from the UMaine Climate Change Institute and the Department of Earth Sciences will participate in the fall meeting of the American Geophysical Union, December 8-12 in San Francisco, California.
Among the topics they will discuss is evidence from Antarctica, Greenland and elsewhere for the global distribution, timing and forcing of Holocene age (the past 11,500 years) abrupt climate change events. Growing scientific evidence supports the idea that significant climate shifts within a decade or less have affected civilizations around the globe and could occur again.
Among UMaine speakers participating in the 2003 AGU fall meeting are the following:
2,500-YEAR CLIMATE BEAT
Kirk Maasch et al. will summarize results from a global synthesis of 50 well dated, well resolved Holocene length paleoclimate records that demonstrate the near-synchronous timing of quasi-2,500 year spaced abrupt climate change events. While significantly subdued relative to their glacial age counterparts, these events are still of significant magnitude and rapid onset and decay to be of significance to humans and ecosystems.
LITTLE ICE AGE
Eric Meyerson et al. will present evidence from two of the most accurately dated polar ice cores (GISP2 in central Greenland and Siple Dome in West Antarctica) to demonstrate that both regions have experienced similar timing for major abrupt climate change events during the Holocene. Examination of the most accurately dated portion of both records, the last 1,500 years (dating error +/-2 years), demonstrates that the most recent abrupt climate change event (nominally the Little Ice Age) was the most dramatic of the last 7,000 years. Utilizing a unique mixture of geographic location and boundary conditions available through the Siple Dome record, researchers have shown that this most recent abrupt climate change event propagated from the Antarctic toward the middle latitudes. The work suggests that the polar regions may be the initial receptor for abrupt climate change events on the order of the Little Ice Age.
Paul Mayewski et al. will present evidence demonstrating that instrumentally calibrated proxies (indirect records) for major features of high latitude circulation developed from ice cores across Antarctica and Greenland reveal strong associations with proxies for solar variability from ice cores. These ice core proxies also offer insight into the potential changes in atmospheric chemistry that link changes in solar output to climate change.
GLASS FROM AFAR
Andrei Kurbatov, et al. will present an analysis of volcanic material, or tephra, from the Law Dome ice core in Antarctica. Focusing on 15 different ice layers holding volcanic glass shards from the past 700 years, Kurbatov and his colleagues have begun to link volcanic eruptions with past atmospheric circulation patterns. Shard composition does not match material from Antarctica, and potential sources include volcanoes in New Zealand and South America. Greg Zielinski, Maine State Climatologist and research professor in the Climate Change Institute, is principal investigator of a National Science Foundation grant for this project.
Alan Wanamaker, et al, will present an ongoing project designed to use the composition of sea shells as a way to understand events related to climate change, such as glacial retreat and ocean temperatures shifts. Oxygen isotopes in sea shells vary according to the temperature and salinity of seawater in which they grow. The abundance of the mussel, Mytilus edulis, makes it a useful species for this purpose. In July, scientists collected 4,800 juvenile mussels from Salt Bay near Damariscotta for use in an experiment that will correlate oxygen isotope ratios in the shells with known water temperatures and salinities. The resulting scientific model will be applied to shells collected in coastal Maine to test hypotheses linking glacial dynamics and climate variability 13,000 to 15,000 years ago, as determined by carbon 14 analysis, with the climate pattern known as the North Atlantic Oscillation.
MAGMA ON THE MOVE
In two separate sessions, Scott Johnson et al will discuss the fundamental chemical and physical processes affecting mineral growth, deformation of the Earth’s crust and magmitic arcs, areas where magma has moved underground into surrounding rock. In presenting the latter, Johnson will use the North Island of New Zealand as a modern analog for understanding the construction of such areas over millions of years.
Peter Koons et al will present evidence in support of a “tectonic aneurysm” model from the northwest Himalayas. Geologists have long known that as mountains rise, erosion can redistribute large amounts of rock and other material. Only recently have the consequences of this process for the Earth’s crust been appreciated. Observations at Nanga Parbat along the Indus River Valley show that erosion has changed the heat profile of the crust leading to further crustal thinning, changes in material flow and locally dramatic deformation. Understanding the dynamics of this process lead the authors to predict where else on the globe this process might be occurring, such as the St. Elias Range in southeast Alaska.
Other UMaine speakers will include: Blue Spikes, snow accumulation rate distribution in Antarctica; Leigh Stearns, ice dynamics of Byrd Glacier, Antarctica; Phaedra Upton, tectonics of Taiwan; Dan Sandweiss, geoarcheological evidence of climate change; Shichang Kang, snow chemistry on Mt Everest; Gordon Hamilton, satellite calibration studies, and scientific outreach.
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