All seminars are held Thursday afternoons in 108 Clark Hall at 4:00 PM. Reception at 3:30 PM in foyer in front of Clark 108.

27 Jan TH
Charles Groat (USGS)Host:Jay Zieman
C A N C E L L E D!

03 Feb TH
Grant Goodell (University of Virginia) Host: Howie Epstein
Bolide Impacts: Facts and Fantasies
Brief abstract:
A debate over the role of catastrophic natural geophysical events in shaping earth history has raged for more than two centuries. Could massive floods, super volcanic eruptions, devastating earthquakes and bolide impacts have periodically caused sudden and devastating environmental changes which result in widespread and almost total extinction of the biosphere? The effects of two bolide impacts will be assessed: the Chesapeake Bolide (Upper Eocene) has been cited as instrumental in the formation of the Bay; the Chicxulube Bolide, on the northern margin of the Yucatan Peninsula, has been blamed for the extinction of the dinosaurs at the end of Cretaceous. But were they? The Chesapeake Crater, the seventh largest presently recognized, resulted in no mass extinctions, was buried by the beginning of Pliocene and the Bay did not form until Pleistocene. The Chicxulube structure is known only in the subsurface from geophysical data. It was first drilled by Pemex in 1966 and, based on extensive coring, was established as an Upper Cretaceous (Campanian) volcanic crater. Following the discovery of the iridium anomaly at the K/T boundary at Gubbio, Italy a global search for a K/T crater was organized. Chicxulube reemerged as a bolide crater, the third largest now known, largely based on its subsurface morphology. However, the crater has now been dated by several methods at 300,000 years before the end of Cretaceous. It's origins are still debated. No mass extinctions or iridium anomalies are recognized at 64.7 mybp And there is growing evidence that there were no mass extinctions at the end of Cretaceous.

10 Feb TH
Jim Smith (Princeton University) Host: Todd Scanlon
Catastrophic rainfall and flooding in the central Appalachians

Brief abstract:
The central Appalachian region has experienced some of the largest rainfall accumulations in the world at time intervals less than 6 hours, including the 18 July 1942 Smethport, Pennsylvania storm (780 mm in 4.5 hours) and the 18 July 1889 storm in Rockport, West Virginia (484 mm in 2 hours, 10 minutes). On 18-19 July 1996, Redbank Creek, which like Smethport, Pennsylvania and Rockport, West Virginia, is located on the western margin of the Appalachian Mountains, experienced record flooding. The 18-19 July 1996 Redbank Creek storm, which consisted of a series of rapidly moving multicell thunderstorms, is examined as a model system for orographic thunderstorms that produce extreme floods along the western margin of the central Appalachians. The Redbank Creek storm is compared with other orographic thunderstorm systems in the central Appalachians that produced catastrophic flooding. The 27 June 1995 Rapidan storm is examined as a model for ``terrain-locked" thunderstorm systems that produce catastrophic flooding along the eastern margin of the central Appalachians. The scale-dependent flood response of the central Appalachians, in particular the role of orographic thunderstorm systems, is examined in the context of the ``Three Floods" paradigm of Miller. New approaches for the experimental study of catastrophic rain storms and their impacts on rivers, hillslopes and ecosystems are discussed.

17 Feb TH
Jordan Barr (University of Virginia) Host: Jose Fuentes

24 Feb TH
Dave Bowling (University of Utah) Host: Jose Fuentes
Stable isotopes and carbon exchange between terrestrial ecosystems and the atmosphere

03 Mar TH
Igor Krupnik (Smithsonian) Host: Carleton Ray
"The Year of the Walrus": A Story of Three Storytellers (Wildlife Biology, Indigenous Knowledge, Cultural Anthropology)

Brief abstract:
There is growing evidence that recent changes in ocean and atmospheric circulation, sea ice distribution, and other physical parameters may soon trigger dramatic restructuring of the Bering Sea ecosystems. The Pacific walrus, one of the key species in the Bering Sea biota, could be an excellent indicator of those changes, because of its close association with the sea ice. It is also crucial to human subsistence, due to its extensive use by local hunters in two dozen indigenous communities in Alaska and Russian Chukchi Peninsula. Native people have thrived in this region by hunting walruses and other marine mammals for over two thousand years. They have developed successful technologies for pursuing, processing, and storing marine mammals to support sustainable consumption. Concerns have been already expressed about prospective negative impact of recent climate change on the Pacific walrus population and Native communities across the northern Bering Sea-Bering Strait region.
The speaker will address different perspectives on the changing walrus-ice-human relationships coming from marine biology, indigenous knowledge, and cultural anthropology. The annual walrus-ice-human cycle, 'the year of the walrus,' will be used as an example, or a case study. Remarkably, those three visions have critical similarities but also some significant gaps and important distinctions. The author (who is cultural and ecological anthropologist) had ample opportunities to see where marine biologists and Native hunters agree or disagree, during some 30 years of his research and fieldwork in local communities in both Alaska and Russian Chukotka, including many years of close partnership with walrus and other sea mammal specialists. The presentation will address the possibility of bridging, or 'integrating' those types of data and knowledge. The author argues that the differences could be somehow rectified through more active knowledge sharing, enhanced documentation of indigenous observations and records, and new methodological approaches. Interdisciplinary scientific partnership is, therefore, vital to further advance, as no single vision could grasp the complexity of the processes and the positions of the key actors involved.

10 Mar TH
NO SEMINAR - SPRING BREAK

17 Mar TH
Kilaparti Ramakrisna (Woods Hole Research) Center Host: Jim Galloway
Policy Approaches for Addressing Global Change

Brief abstract:
The world community successfully tried new approaches in addressing global climate change. These include the systems in place to understand complex scientific issues and incorporate them in policy making processes. A review of the lasting significance of these measures will be discussed.

24 Mar TH
Bill Dennison (University of Maryland) Host: Karen McGlathery
Chesapeake Bay Restoration in Perspective: Ecological Forecasting, Ecosystem Health Assessment and Global Lessons

Brief abstract:
A large scale restoration effort is being undertaken for Chesapeake Bay and its watershed. This effort has been held up as a world model for environmental management, yet recent analyses have put into question the efficacy of Chesapeake Bay restoration. Part of the concern has been the confusion of modeling vs. monitoring results. Recently, a revision of the monitoring approach has been initiated. An ecological forecast will be produced in late spring 2005 for summer hypoxia conditions, harmful Microcystis blooms in the Potomac River and the trends of bay grasses in low, mid and high salinity regimes. These ecological forecasts will be based on winter/spring river flow and weather predictions. In the autumn, an evaluation of the summer forecasts and any other noteworthy events will be publicized. In winter, an assessment of Chesapeake Bay ecosystem health will be made by combining water quality, living resource and habitat indicators. The Chesapeake Bay ecosystem assessment will be geographically explicit and quantitative, and modeled after other effective programs. This combination of annual forecasts, evaluations and assessments will improve the communication of Chesapeake Bay ecosystem health and associated restoration activities to stakeholders and the interested public. Global lessons of ecosystem restoration efforts will be applied to the Chesapeake restoration effort so that it can indeed be considered a world model for environmental management.

31 Mar TH
MOORE LECTURE: Lonnie Thompson (Ohio State) Host: Steve Macko
Rapid Climate Change in the Earth System: Present, Past, and Future

Brief abstract:
THINGS WE KNOW WITH CERTAINTY The clearest evidence for major climate warming underway today comes from the tropical glaciers, recorded in both the ice core records and in the drastic and accelerating retreats of both total area and total ice volume. The rapid retreat of these glaciers causes grave concern for three reasons. First, these glaciers are the world's "water towers", and their loss threatens water resources necessary for hydroelectric production, crop irrigation, and municipal water supplies for many nations of the world. The ice fields constitute a "bank account" that is drawn upon during dry times to feed and energize populations downstream. The current melting is cashing in on that bank account that was built up over thousands of years, but is not currently being replenished. Second, these ice fields contain paleoclimate histories that are unattainable elsewhere and, as the ice fields melt, the records preserved therein are lost forever. The records are needed to discern how climate has changed in the past in these sensitive regions and to assist in predicting future change. Finally, one of the important aspects of glacier retreat on a global scale is the potential contribution that it makes to sea-level rise.

THINGS THAT, ON THE EVIDENCE, SEEM PROBABLE Most likely the tropical glaciers are "the canaries in the coal mine" for the global climate system. They integrate many variables in the climate system i.e., temperature, precipitation, cloudiness, radiation....but the key is they integrate the climate as a whole and response to it. The fact that all tropical glaciers are retreating should concern us all as it is occurring in a region of the world noted for its climatic uniformity. A composite of the decadally-averaged oxygen isotopic records from three Andean and three Tibetan ice cores over the last two millennia shows a 20th century isotopic enrichment that suggests a large scale warming is underway at low latitudes. In concert with this apparent warming, in situ observations reveal that tropical glaciers are currently disappearing. For example, the Qori Kalis Glacier in Peru now retreats 205 meters per year more that 40 times faster than it did in 1978. Similarly, the ice on Mount Kilimanjaro, Africa, covered ~12.1 square kilometers in 1912, but less than 2.6 square kilometers remains today. If the current rate of retreat continues, the perennial ice on Kilimanjaro will disappear within the next 15 to 20 years, the first time in the past 11,700 years that Kilimanjaro will be devoid of ice. Thus within the next two decades many of the tropical glaciers will likely disappear along with the archive of past climate that they contain.

THINGS THAT SEEM LIKELY BUT WILL REQUIRE FURTHER EVIDENCE The rate and the scale of retreat of mountain glaciers both north and south of the equator is truly amazing at the end of the 20th Century and beginning of the 21st Century, however to provide the time perspective needed to evaluate the significance of these changes we must develop and extend our time perspective through both the archive preserved in the mountain glaciers as well as from dating what is being released by the ice as it retreats. Abrupt climate change now underway in the Peruvian Andes is placed within a longer time perspective using additional tropical ice core records and 14 C AMS dated plant material exposed in 2002 by retreating ice. The ~5200 year old plant, growing above its current altitudinal range, indicates warmer Early Holocene conditions, consistent with stable isotopic records from tropical ice cores. Multiple lines of evidence from Africa, the Middle East, Europe and South America indicated an abrupt mid-Holocene climate event in the low latitude. We need to understand the nature and cause of abrupt climate events in the tropics where 50% of the surface of the planet lies and where some 70% of the global population lives. Glaciers likely represent threshold systems, such that as the 0ºC isotherm rises to ever higher elevations the mass loss process changes abruptly from that dominated by sublimation to that dominated by the much more energy efficient melting process. Evidence for this transition occurring as recently as 1991 for the lower 5,670 meter elevation Quelccaya ice cap and 2003 for the higher 5895 meter elevation ice fields of Kilimanjaro are presented. The discovery of over 50,000 years old plants at the retreating margin of the Quelccaya Ice Cap in 2004 argues that the current warming in the Andes of Peru is unprecedented in over 50,000 years.

06 Apr W
John Lamoreaux (University of Virginia) Host: Hank Shugart
What Do Global Distribution Patterns of Terrestrial Vertebrates Tell Us About How to Slow the Extinction Crisis?

07 Apr TH
Deborah Clark (University of Missouri - St. Louis) Host: Deb Lawrence

14 Apr TH
Pei-Jen Lee (University of Virginia) Host: Steve Macko

20 Apr W
Deborah Stein (University of Virginia) Host: Steve Macko
Long Range Transport Trends and Mechanisms for Trace Gases and Aerosols over Southern Africa During a La Nina Year

21 Apr TH
Bill Gilhooly (University of Virginia) Host: Steve Macko

27 Apr W
Kevin Levey (University of Virginia) Host:Bob Davis
Bridging the gap between cause and effect: Rain-bearing systems responsible for high rain days over northeastern South Africa

28 Apr TH
Drew Shindell (NASA GISS, Columbia University) Host: Mike Mann
Continental-scale climate response to external forcings

Brief abstract:
While climate models can do a good job of reproducing past global annual average surface temperature changes, capturing the spatial pattern is much more challenging. In many ways, however, this presents a much more rigorous test of climate models. We report on simulations of climate during the past several centuries using the Goddard Institute for Space Studies climate model investigating the response to a variety of external forcings. These include changes in greenhouse gases, volcanic aerosols, solar irradiance, ozone and tropospheric aerosols. Though difficulties remain in capturing observed changes at regional scales, models are improving. We highlight the role of stratospheric perturbations in affecting large-scale climate variability patterns. In historical times, we argue that the spatial pattern and annual cycle of temperature changes provide better tests of models than the overall temperature change. We also show that atmospheric chemistry contributes strongly to the response to solar variability. For the 20th century, chemistry and emission distributions determined the spatially inhomogeneous forcings from tropospheric ozone and aerosols, which we show have contributed to geographical variations in climate trends.

05 MayTH
Court Strong (University of Virginia)Host: Bob Davis
Upper tropospheric flow over the Northern Hemisphere: 1948-2004

Environmental Sciences Department 291 McCormick Rd Charlottesville, Virginia (434) 924-7761