2000 Annual Meeting and Arctic Forum | Presentation Abstracts
Paper Abstracts | Poster Abstracts
Paper (Oral) Presentation AbstractsIn alphabetical order by first author's last name.
Decadal variability of the Greenland Ice
Sheet mass balance as a cause of the "Great Salinity
Anomalies" in the northern North
Atlantic
Igor M. Belkin, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, Phone: 401/874-6533, Fax: 401/874-6728, ibelkin@gso.uri.edu
The "Great Salinity Anomalies" (GSA) originated in the early 1970s, 1980s and 1990s, and propagated around the Subarctic Gyre (Belkin et al., 1998). The GSAs appeared as low-S/low-T anomalies (initially, ~1.0 ppt/1°C, respectively) associated with a positive anomaly of sea ice cover (GSA70: 330,000 km2, Greenland/Iceland Seas; GSA80: 410,000 km2, Labrador Sea/Baffin Bay). The GSA70 initial salt deficit was ~72 Gt; roughly the same assumed for GSA80 and 90. Thus ~2,000 km3 of fresh water would form a GSA. The GSA70 formed in the Greenland/Iceland Seas due to the enhanced Arctic freshwater/ice export via Fram Strait, whereas the GSA80 and GSA90 formed in the Labrador Sea-Baffin Bay due to wintertime atmospheric forcing, likely associated with the enhanced Arctic freshwater export via the Canadian Archipelago. The above mechanisms explain the GSAs quite well. It was noted, however (Belkin et al., 1998), that all three GSAs were associated with icebergs armadas in the NW Atlantic, whose source was the Greenland Ice Sheet (GIS), hence the GIS iceberg discharge variations might be related to the GSA formation.
Variations of the GIS icebergs discharge and meltwater runoff could produce a low-S anomaly because:
- The GIS discharge feeds the East/West Greenland Currents (EGC/WGC), then the Labrador Current (LC) exports it to the open NW Atlantic;
- The EGC looses freshwater only north of the Denmark Strait (to the East Icelandic Current), where the GIS discharge is small;
- The GIS discharge occurs mainly south of the Denmark Strait, where the EGC/WGC receive water, not loose it, so the GIS discharge remains trapped in the EGC-WGC-LC, and therefore can fully contribute to the GSA formation.
The iceberg discharge and meltwater runoff from the GIS might have been an alternative, or a complementary, mechanism accountable for the formation of the GSAs, observed in the second half of the 20th century. Under different climatic conditions, however, this mechanism might be solely responsible for the GSA origin. Such conditions had occurred in the past, leading to Heinrich events, and they might be encountered in the future.
References:
Belkin, I.M., S. Levitus, J. Antonov, and S.-A.-Malmberg. 1998. "Great Salinity Anomalies" in the North Atlantic. Progress in Oceanography 41, 1-68.
Foraging strategies of subarctic wood bison: energy maximizing or time minimizing?
Carita M. Bergman, Department of
Zoology, University of Guelph, Guelph, ON N1G 2W1
Canada, Phone: 519/824-4120 ext 6307, Fax:
519/767-1656, cbergman@uoguelph.ca
John M. Fryxell, Department of
Zoology, University of Guelph, Phone: 519/824-4120,
ext 3630, jfryxell@uoguelph.ca
C. Cormack Gates, Faculty of
Environmental Design, University of Calgary, Calgary,
AB T2N 1N4, Canada, Phone: 403/220-3027, ccgates@nucleus.com
Daniel Fortin, Department of
Zoology, University of Guelph, Phone: 519/824-4120
ext 6307, dfortin@uoguelph.ca
Many classical models of ungulate foraging are premised on energy maximization, yet limited empirical evidence and untested currency assumptions make the choice of currency a nontrivial issue. The primary constraints on forage intake of ungulates are forage quality and availability. Using a model that incorporates these dual constraints, we predicted the optimal biomass of forage patches for subarctic ungulate grazers using an energy maximizing versus a time minimizing strategy. We tested these predictions on wood bison (Bison bison athabascae) grazing naturally occurring sedge (Carex atherodes). The digestive constraint was determined by a series of ad libitum feeding trials using sedge at different stages of growth. Sedge digestibility declined with biomass. Ad libitum intake of sedge by bison declined with sedge digestibility and thus decreased with sedge biomass. On the other hand, short-term sedge intake rates of wood bison increased with biomass. Incorporation of these constraints resulted in the prediction that daily energy gain of bison should be maximized by grazing patches with a biomass of 10 g/m2, whereas a satisficing bison could minimize daily foraging time needed to fulfill its energy requirement by cropping patches with a biomass of 279 g/m2. To test these predictions, we used a staggered mowing regime to convert even-aged stands of sedge to a mosaic of patches varying in quality and quantity. Observations of bison grazing these mosaics indicated that patches of biomass below 120 g/m2 were avoided, while the patches of biomass 156 and 219 g/m2 were highly preferred, with the greatest preference for the latter. These results indicate that bison were behaving as time minimizers rather than energy maximizers. Daily cropping times of free-ranging bison from the literature corroborate our results.
Millennial-scale global events recorded in
El'gygytgyn Crater Lake, eastern Siberia back to 400
ka
Julie Brigham-Grette, University
Massachusetts, Department of Geosciences, Amherst, MA
01003, brigham-grette@geo.umass.edu
Olga Glushkova, North East
Interdisciplinary Scientific, Research Institute, 16
Portovaya, Magadan 685010, Russia, strujkov@trumpe.neisri.magadan.su
Paul Minyuk, North East
Interdisciplinary Scientific, Research Institute,
paleomagn@neisri.magadan.su
Martin Melles, Alfred Wegener
Institute for Polar and Marine Research,
Telegrafenberg A43, D-14473 Potsdam, Germany,
mmelles@awi-potsdam.de
Norbert R. Nowaczyk,
GeoForschungsZentrum, Telegrafenberg Haus C, D-14473
Potsdam, Germany, nowa@gfz-potsdam.de
A.V. Lozhkin, North East
Interdisciplinary Scientific Research Institute
P. Anderson, Quaternary Research
Center, University of Washington, Seattle, WA
98195-1360, pata@u.washington.edu
M.V. Cherepanov, Institute of
Biology and Soil Sciences, Far East Branch of the
Russian Academy of Sciences, Department of
Paleobotany, Prospect 100-Letiya 159, Vladivostok -
22 690022, Russia, evolut@ibss.marine.su
C. Cosby, University Massachusetts,
Department of Geosciences, ccosby@geo.umass.edu
Paul Layer, Department of Geology
and Geophysics, University of Alaska, Fairbanks, AK
99775, player@gi.alaska.edu
Steve L. Forman, Department of Earth
and Environmental Sciences (M/C 186), University of
Illinois at Chicago, 845 West Taylor Street, Chicago,
IL 60607-7059, slf@uic.edu
El'gygytgyn Lake, located 100 km north of the Arctic Circle in northeast Russia (67° 30' N latitude and 172° 05' E longitude), was created 3.6 million years ago (n=11 Ar/Ar ages, Layer, in press) by a meteorite impact that generated a crater roughly 20 km in diameter. An international expedition to the lake in May, 1998, successfully recovered sediment cores from the center of the 15 km wide basin, penetrating nearly 13 meters in 175 m water depth using a percussion piston corer from the lake ice surface. The sediments consist of massive to finely laminated grayish to greenish muds with discrete intervals containing authigenic vivianite and perhaps lake ice-rafted clay clasts. Sub-millimeter laminated sections vary in thickness from 10 to 40 cm and represent intervals when the lake floor became anoxic (consistent with more vivianite). Distinct fluctuations in various sedimentological (stratification, clasts), physical (susceptibility), biochemical (TOC, TN, TS, d13TOC), and paleoecological (pollen, diatoms) parameters provide firm evidence that El'gygytgyn Lake and its catchment respond to environmental change at millennial time scales.
Geochronology on the core, including the timing of pollen transitions, the occurrence of the Blake (ca. 110 ka) and Laschamp (ca. 42 ka) magnetic excursions, optical luminescence ages and new AMS 14C ages, confirms that our 13 m core extends back possibly as old as 400 ka; we are most confident to Marine Isotope Stage 6. Assuming our age model is correct, then Holocene and interglacial sedimentation rates averaged about 8ñ10 cm/1000 yrs., while rates during the Last Glacial Maximum may have been as low as 4 cm/1000 yrs. Nevertheless, magnetic susceptibility clearly records the Younger Dryas event, stronger Dansgaard/Oeschger-Henrich tandems (like D/O-b) but especially D/O interstadials 19 and 20, an inter-stage 5d event, and the "YD-like" event at the stage 5/6 transition. The striking similarity between the El'gygytgyn magnetic susceptibility record, the GISP2/GRIP d18O records from the Greenland Ice Sheet (to 110 ka, Grootes et al., 1993), and some events recorded in carbonate records from the Bermuda Rise (Adkins et al., 1997) and Bahama Outer Ridge (Keigwin et al., 1994) provides the possibility for evaluating circumarctic and global teleconnections between ice core, marine, and terrestrial archives. Our geochronology is not good enough to fully determine leads and lags. In any case the lake sediment contains the best resolved record of the last interglacial (all of isotope stage 5) and the longest terrestrial record of millennial scale climate change anywhere in the Arctic.
References:
Adkins, J.F., E.A. Boyle, L.D. Keigwin, and E. Cortijo. 1997. Variability of the North Atlantic thermohaline circulation during the last interglacial period. Nature 390, 154-156.
Grootes, P.M., M. Stuiver, J.W.C. White, S. Johnsen, and J. Jouzel. 1993 Comparison of oxygen isotope records from GISP2 and GRIP Greenland ice cores. Nature 366, 552+.
Keigwin, L.D., W.B. Curry, S.J. Lehman, and S. Johnson. 1994. The role of the deep ocean in North Atlantic climate change between 70 and 130 kyr ago. Nature 371, 323-326.
Layer, P.W. 40Ar/39Ar age of the El'gygytgyn impact event, Chukotka, Russia Meteoritics and Planetary Science (in press).
A perspective on present and future oceanographic studies in the Canadian Arctic: change and biodiversity
Eddy Carmack, Institute of Ocean Sciences, Department of Fisheries and Oceans (Canada), 9860 West Saanich Road, Sidney, BC V8L 4B2, Phone: 250/363-6585, Fax: 250/363-6746, carmacke@dfo-mpo.gc.ca
Much of the current oceanographic research conducted in Arctic Canada is focused on climate change and living resources. It is thus natural to combine the two issues and ask: What is the role of the physical environment in biodiversity? In fact, the Arctic is an ideal site to address such a question. First, climate change is accepted to be amplified at the high latitudes. Second, climate change in the Arctic can impact biota from both bottom-up (e.g., Changes in light or nutrient delivery) and top-down (e.g., By disturbing predator-prey relations) effects. The duality of bottom-up and top-down effects will be felt in both the seasonal ice zone (SIZ) and in the riverine coastal domain (RCD). The former (SIZ) affects not only light and nutrients, but also comprises an important habitat for marine fish and mammals. The latter (RCD) represents not only a supply of nutrients, but also a transport corridor for larvae and anadromous fish.
"If you got everything, it's good enough":
perspectives on successful aging in a Canadian Inuit
Community
Peter Collings, Department of Anthropology, Pennsylvania State University, State College, PA 16803; Current Address: Department of Anthropology, Indiana University of Pennsylvania, G12B McElhaney Hall, Indiana, PA 15705-1087, Phone: 724/357-2117, Fax: 724/357-7637, collings@grove.iup.edu
Structured interviews with 38 Inuit in the community of Holman were conducted to examine Inuit definitions of successful and unsuccessful aging. Qualitative analysis of the interview data suggests that 1) contrary to much of the literature about culture change in the Canadian North, there appear to be no significant differences in the ways Inuit of different age cohorts view aging and elderhood; 2) a successful old age is not one necessarily characterized by individual good health, but rather by the ability of the individual to successfully manage declining health; and 3) for Inuit, the most important determinants of a successful elderhood are not material, but ideololgical. That is, an individual's attitudes in late life, and in particular their willingness to transmit their accumulated wisdom and knowledge to their juniors, are the critical determinants of whether an elder is viewed as having a successful old age.
Magma storage and mixing conditions for the
1953ñ68 eruption of Southwest Trident volcano, Katmai
National Park, Alaska
Michelle Coombs, Department of
Geology and Geophysics, University of Alaska
Fairbanks, PO Box 755780, Fairbanks, AK 99775-5780,
Phone: 907/474-7375, Fax: 907/474-5163, ftmlc@uaf.edu
John C. Eichelberger, Department of
Geology and Geophysics, University of Alaska
Fairbanks, Phone: 907/474-5530, Fax: 907/474-7290,
eich@dino.gi.alaska.edu
Malcolm J. Rutherford, Department of
Geological Sciences, Brown University, Providence, RI
02912, Phone: 401/863-3338 ext 1927, Fax:
401/863-2058, mjr@brown.edu
Between 1953 and 1968, approximately 0.5 km3 of andesite and dacite erupted from a newly formed vent on the southwest flanks of Trident volcano in Katmai National Park, Alaska, forming an edifice now known as Southwest (New) Trident. Field, analytical, and experimental evidence shows that the eruption commenced soon after mixing of dacite and andesite magmas at shallow crustal levels. Four laval flows (58.3ñ65.5 wt % SiO2) are the dominant result of the eruption; these contain discrete andesitic enclaves (55.8ñ57.2 wt % SiO2) as well as micro- and macro-scale compositional banding. Tephra from the eruption spans the same compositional range as lava flows; however, andesite scoria (56ñ58.1 wt % SiO2) is more abundant relative to dacite tephra, and is the explosively erupted counterpart to andesite enclaves. Fe-Ti oxide pairs from andesite scoria show a limited temperature range clustered at 1000°C. Temperatures from grains found in dacite lavas possess a wider range; however, cores from large (>100 µm) magnetite and coexisting ilmenite give temperatures of ~890°C, taken to represent a pre-mixing temperature for the dacite. Water contents from dacite phenocryst melt inclusions and phase equilibia experiments on the andesite show that the two magmas last resided at a water pressure of 90 MPa, and contained ~3.5 wt % H2O, equivalent to 3 km depth. Unzoned pyroxene and sodic plagioclase in the dacite indicate that it likely underwent significant crystallization at this depth; highly resorbed anorthitic plagioclase from the andesite indicates that it originated at greater depths and underwent relatively rapid ascent until it reached 3 km, mixed with dacite, and erupted. Diffusion profiles in phenocrysts suggest that mixing preceded eruption of earliest lava by approximately one month. The lack of any compositional gap in the erupted rock suite indicates that thorough mixing of the andesite and dacite occurred quickly, probably due to low density and viscosity differences. Disaggregation of enclaves, phenocryst transfer from one magma to another, and direct mixing of compositionally distinct melt phases were the three mechanisms by which hybridization was accomplished.
Living on the edge: archaeology and coastal dynamics along the Gulf of Alaska coast
Aron L. Crowell, Arctic Studies Center, Smithsonian Institution, Alaska Regional Office, Anchorage Museum of History and Art, West 7th Avenue, Anchorage, AK 99501, Phone: 907/343-6162, Fax: 907/343-6130, aronc@muskox.alaska.edu
Alutiiq, Tlingit, and Dena'ina peoples and their ancestors have lived along the geologically dynamic coastline of the Gulf of Alaska for 10,000 years, simultaneously at the edge of the sea and on the margin of colliding tectonic plates. Earthquakes, tidal waves, volcanic eruptions, glacial advances, and sinking shorelines are common and sometimes catastrophic occurrences, remembered in Native oral history and evident in the archaeological record of the region. Oral traditions, historical documents, and archaeological data also offer insight into climate change in the region, including changes brought about by the Little Ice Age. Interdisciplinary field studies conducted in five Gulf of Alaska parks by the Smithsonian Institution and National Park Service (1993ñ1996) indicate that local Holocene glacial, climatic, tectonic, and sea level histories must be reconstructed as a first step toward regional level interpretations.
Animals as agents of landscape evolution in
the Arctic: The unquantified element
Kevin Hall, Geography Program, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9, Canada, Phone: 250/960-5864, Fax: 250/960-5538, hall@unbc.ca
The biology of Arctic animals has long been a major research topic as too have been the role of animals within the Arctic ecosystem and within the lifestyle of indigenous peoples. Animals are also recognised to play a significant role within Arctic ecotourism. What has not received attention is the actual role of the animals within the landscape, that they play a geomorphic role (potentially) comparable to other Arctic landform agents such as glaciers, rivers, mass movement, etc. At one level this is surprising. Much of the Arctic is a region of fragile flora coupled with thermally sensitive permafrost, within which occur mobile, large herds of mammals coupled with less mobile small, burrowing mammals. Present day numbers may also be far smaller than in the recent past when other mega-fauna such as mastodon and wooly rhinoceros were abundant. Any disturbance, particularly to permafrost conditions, by the action of these animals (direct erosion, compaction, trampling, overgrazing, etc.) can lead to a whole range of geomorphic responsesÑfrom thermokarst to slope failure. The impact of the animals is further exacerbated by other geomorphic processes (e.g. needle ice, slope wash, aeolian erosion, etc.). In many instances, it is the ability of these other geomorphic processes to now operate as a result of animal action that is a major factor in landscape development, and one that is overlooked in landscape evolution. An example of an Arctic landform (dells) being created by musk ox will be presented. The significance of Arctic zoogeomorphology will also be put in the context of the necessity for its understanding for sustainable development or maintenance of Arctic park areas, especially under potentially changeable climatic conditions.
CAPT Michael A. Healy: The man, his ships and
the Healy
George Harper, Blacks in Alaska History Project Inc., PO Box 143507, Anchorage, AK 99514-3507, Phone: 907/333-4719, Fax: 907/333-4238, akblkhist@gci.net
To commemorate the launching of the U.S. Coast Guard Cutter Healy, Mr. Harper collected historical photographs from the Healy family, the U.S. Coast Guard, Georgetown University, the National Archives, builders of the cutter, newspapers and museums. In this slide presentation, Mr. Harper emphasizes one man's impact on Alaska history. His talk covers the history of the Healy family, the naval career of CAPT Healy, and the ships on which he served, including the famous Revenue Cutter Bear. Mr. Harper also will discuss the events surrounding the naming of the Cutter Healy and present photographs of the vessel's launching.
The Arctic upper atmosphere as a harbinger of global change and space weather
John Kelly, Ionospheric and Space Physics Group, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, Phone: 650/859-3749, Fax: 650/322-2318, kelly@sri.com
The Arctic upper atmosphere is an extremely sensitive region that reacts measurably to small changes in chemistry, temperature, and solar inputs. Severe solar eruptions and the resulting solar wind can cause major changes to the Arctic upper atmosphere including greatly expanding the auroral oval, causing polar cap absorption, and the induction of large ionospheric electric currents. Ground-based instruments in the Arctic as well as from spacecraft instrumentation can measure these affects. The changes in ionospheric parameters resulting from the energy input carried by the solar wind is used by modelers to predict the effects of space weather on human activity. Also, the Arctic mesosphere (the coldest place on earth) is the location of polar mesospheric clouds, noctilucent clouds and metallic layers. Chemical changes and material transport, some of which results from human activity influence the existence of these clouds and layers.
Methane emissions and transport by arctic
sedges in Alaska: results of a vegetation removal
experiment
Jennifer Y. King, Department of
Earth System Science, University of California, 220
Rowland Hall 3100, Irvine, CA 92697-3100; Current
Address: Plant-Soil-Nutrient Research Unit,
USDAñAgricultural Research Service, PO Box E, Fort
Collins, CO 80522-0470, Phone: 970/490-8255, Fax:
970/490-8213, jyking@lamar.colostate.edu
William S. Reeburgh, Department of
Earth System Science, University of California,
Irvine, Phone: 949/824-2986, Fax: 949-824-3256,
reeburgn@uci.edu
Shannon K. Regli, Department of
Earth System Science, University of California,
Irvine
Methane flux and belowground methane profile studies were conducted in a wet meadow vegetation manipulation site at the Toolik Lake Long-Term Ecological Research (LTER) site during the summers of 1995 and 1996. Control plots, moss-removal plots, and sedge-removal plots were studied to determine the role of these vegetation types in wetland methane emission and to study the gas transport mechanism. Methane emission was greatest from plots with intact sedges. Depth distributions of root density collected in 1995 showed a strong inverse relationship to porewater methane concentration. Results on insertion of arrays of gas-permeable silicone rubber tubing into the soil indicate that they are reasonable analogs for the physical process of gaseous diffusion through plants. The observed differences in flux between plots with and without sedges cannot be fully explained by differences in methane production or dissolved organic carbon concentrations in our measurements.
Towards prediction of Arctic climate change
Wieslaw Maslowski, Department of Oceanography, Naval Postgraduate School, 833 Dyer Road, Monterey, CA 93943, Phone: 831/656-3162, Fax: 831/656-3162, maslowsk@ucar.edu
Analysis of atmospheric sea level pressure (SLP) fields in the Northern Hemisphere (NH) for this century indicates an increased variability since the mid-1960s. In attempt to explain the Arctic Ocean response to such changes, results are presented from a high resolution, regional, coupled ice-ocean model, forced with realistic atmospheric data derived from the European Centre for Medium-range Weather Forecasts (ECMWF) for 1979ñ1998. The model resolution is 18 km and 30 levels and its rotated numerical grid includes the Arctic Ocean, Nordic Seas, Canadian Archipelago and sub-polar North Atlantic. The model consists of an ocean general circulation model (OGCM) adapted to the Pan-Arctic region, coupled to a viscous-plastic, dynamic-thermodynamic sea ice model. The primary integration uses daily-averaged 1979 atmospheric data repeated for 20 years and then continues with interannual forcing for 1979ñ1998. Analysis of model output allows for improved understanding of the ice-ocean system response to the atmospheric circulation and its variability over the Arctic Ocean.
The cyclonic (or eastward) shift in ice and ocean circulation, distribution of fresh water and extent of Atlantic Water has been determined when comparing conditions between the early 1980s and 1990s. A new opposite trend is modeled during the late 1990s. It appears to have a tendency to reverse large-scale conditions of the ice-ocean system to its state known from the 1970s and 1980s, implying an oscillatory behavior of the system. Both sea ice and the upper ocean circulation as well as fresh water export from the Russian shelves and the intensified re-circulation of Atlantic Water within the Eurasian Basin indicate that the Arctic Ocean climate is undergoing another shift. Interannual variability of the atmospheric conditions appears to be the main and sufficient driver of modeled changes in the sea ice and ocean below during the last two decades. Additional data for the late 1990s, especially from the Eurasian Basin, is needed in order to verify the model prediction of the latest climate change in the Arctic.
More results and animations of selected model fields are presented at a poster in the Arctic Forum poster session.
Marine mammals and seabirds as indicators of environmental variability in the Arctic
Sue E. Moore, National Marine Mammal Laboratory, NOAA/NMFS/AFSC, 7600 Sand Point Way, Seattle, WA 98115, Phone: 206/526-4021, Fax: 206/526-6615, sue.moore@noaa.gov
Marine mammals and seabirds are excellent indicators of environmental variability. Multiple studies, from the poles to the tropics, attest to their correspondence with meso-scale zones of oceanic productivity. In the Arctic, many species also serve the nutritive and spiritual needs of Native communities, as a primary source of food and a cultural keystone. Thus, environmental changes that effect seabirds and marine mammals also effect the health and well being of human inhabitants of the Arctic. What then can we learn by studying how marine mammals and seabirds respond to environmental variability? In short, we can explore Arctic ecological pathways from the top down. Research to date provides a rudimentary understanding of seabird and marine mammal responses to a changing environment. For example, black guillemots and horned puffins have expanded their nesting range to Cooper Island near Barrow, Alaska, during the warming period of the last three decades. On a longer timeline, dovekies now routinely nest at high latatiudes along the coasts of Greenland and Svalbard, as compared to fossil evidence of occurrence as far south as France. Finally, the oscillating dominance of common or thick billed murres on the Pribilof Islands reflect abrupt changes in marine community structure coincident with atmospherically driven oceanic regime shifts over the last four decades.
Perhaps because they are more elusive research subjects, clear examples of marine mammal responses to environmental variability are rare. Walrus and seals (ringed, bearded, spotted) depend in part on sea ice as a platform for breeding, feeding and resting, so significant changes in ice thickness or extent have immediate ramifications. For example, foraging by Pacific walrus is compromised when, during extreme ice-minima years (e.g., 1990 and 1997), their floating haul-outs retreat from productive Chukchi shelf waters into the deep basins of the central Arctic. Changes in whales' use of habitat and migration corridors are somewhat harder to discern. Bowhead, beluga and gray whales have distinct summer and autumn habitats offshore Alaska, with autumn habitat selection seemingly influenced by sea ice cover and transport (inflow) at Bering Strait. During the autumn migration, bowheads remain further offshore, in outer shelf and slope waters (50ñ2,000 m depth) when ice conditions are heavy (> 70% surface cover), but aggregate nearshore in inner-shelf waters (< 50 m depth) during years of open-water or light ice conditions. In contrast, belugas prefer slope and basin waters (> 200 m depth), no matter the ice conditions. Transport, rather than ice cover, seems to influence gray whale habitat selection, and possibly residence time in the Arctic prior to their autumn southbound migration. In years of high in-flow at Bering Strait, gray whales are especially tenacious in their use of shallow shoal waters of the Chukchi Sea, feeding there well into October.
While each of these scenarios can theoretically be related to prey availability, they provide a comparatively static view of whale responses to a changing environment. More dramatic are insights to whale movements, relative to physical features, provided by passive acoustic detection of calling bowhead whales, and by satellite-tagged belugas. A census for bowhead whales has been conducted periodically from Point Barrow since the late 1970s, augmented by acoustic detection of calling whales since the mid-1980s. Using acoustic-based tracking, the dynamic nature of the herd structure as it passes Barrow and weaves around ice has been described, with deep-keel "old" ice acting as barriers to migration, while smooth "new" ice poses no such restriction. On a much broader scale, the dramatic movements of belugas, from both the Eastern Chukchi Sea and the Beaufort Sea stocks, has recently exhilarated researchers. Satellite-tagged whales have moved swiftly from shallow coastal waters to the deep Arctic basin, sometimes transiting over 1,000 km through very heavy ice conditions in a matter of a few days. Notably, as in sighting-based studies, belugas seemed to favor continental slope, canyon, and basin habitats. As apex predators in the Arctic, belugas are subject to comparatively high contaminant burdens through biomagnification processes, which in turn are passed on to Native consumers. This trophic position, coupled with their broad-scale movements suggest these whales, perhaps more than any other species, have the potential to integrate large-scale ecosystem variability and act as sentinels to environmental change in the Arctic.
Update on the Study of Environmental Arctic Change (SEARCH)
James Morison, Polar Science CenterÐApplied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698, Phone: 206/543-1394, Fax: 206/616-3142, morison@apl.washington.edu
The Study of Environmental Arctic Change is being developed to understand the present and future course of the changes that have occurred in the Arctic over the last 10ñ20 years. These include a change in atmospheric circulation, ice conditions, and ocean circulation. The program has been developed over the last 2ñ3 years with the support of the Arctic Program of the NSF Office of Polar Programs. However, in recent developments SEARCH has taken on an increasingly interagency character. In addition to NSF, NOAA, ONR, NASA, and DOE began developing an interagency SEARCH program. SEARCH has been made an integral part of the Interagency Arctic Policy Committee (IARPC) 5-year plan. The IARPC met recently and formed an official Interagency Working Group for SEARCH with the mandate of developing intermediate and long-range plans for an interagency SEARCH effort. Such a program will take advantage of the special strengths of each agency to develop a broad yet coherent effort. In other developments SEARCH has been adopted as a third element of the US-CLIVAR program. This gives SEARCH a connection to the international climate research effort that it needs.
Distribution of d13C in sediment organic carbon, Arctic Amerasian continental Margin
A. Sathy Naidu, Institute of Marine Science, PO Box 757220, University of Alaska Fairbanks, Fairbanks, AK 99775-7220, Phone: 907/474-7032, Fax: 907/474-5863, ffsan@uaf.edu
Recently Naidu et al. (2000) reported that there is a cross-shelf seaward increase in d13C of total organic carbon (TOC) of the continental margin sediments of the North Bering-Chukchi-East Siberian-Beaufort Sea, Arctic Amerasia. This trend is explained by a decrease in the deposition of land-derived TOC seaward from the coast. The terrestrial component of the TOC in the shelf sediments of the margin is estimated to be 35ñ70%. The above distribution pattern in d13C has a potential application in reconstructing the paleoceanography of the Amerasian margin, especially in context of changes in the relative proportions of supply and deposition of TOC from land and marine sources resulting from glacial-interglacial sea-level fluctuations. Further, it is suggested that the recycling and transport of terrestrially-derived carbon from the extensive Amerasian shelf could be a process causing the elevated total CO2 in the upper halocline of the Arctic Basin.
Reference:
Naidu, A.S., L.W. Cooper, B.P. Finney, R.W. Macdonald, C. Alexander, and I.P. Semiletov. 2000. Organic carbon isotope ratios (d13C) of Arctic Amerasian continental shelf sediments. Geologische Rundschau, Special Issue, R. Stein (ed.), In press.
Arctic Clouds at the Edge of
Space
John Olivero, Physical Sciences Department, Embry-Riddle Aeronautical University, 600 South Clyde Morris Boulevard, Daytona Beach, FL 32114-3900, Phone: 904/226-6709, Fax: 904/226-6713, oliveroj@db.erau.edu
Called Noctilicunt Clouds or Polar Mesospheric Clouds, these wispy silvery blue, light scattering layers are visible from the Earth's surface at high latitudes in mid-summer. Indirect evidence supports the hypothesis that these clouds are composed of water ice formed at the coldest point of the Earth system. Reliable observations of this phenomenon range back perhaps 120 years. There is a compelling scenario which attributes these lovely spectacles in the night sky to the long term rise of methane and carbon dioxide in the atmosphereÑhence they may have been the earliest signal of global change.
Impacts of climate change on the Arctic coastal indigenous people
Caleb Pungowiyi, Special Advisor on Native Affairs, Marine Mammal Commission, and Robert Aqqaluk Newlin Sr. Memorial Trust, PO Box 509, Kotzebue, AK 99752, Phone: 907/442-1611, Fax: 907/442-2289, caleb.pungowiyi@nana-reg.com
Abstract not available.
Why is the Arctic ice cover so thin?
Drew Rothrock, Polar Science Center - Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698, Phone: 206/685-2262, Fax: 206/616-3142, rothrock@apl.washington.edu
Abstract not available.
The summer Arctic frontal zone as seen in the
NCEP/NCAR reanalysis
Mark C. Serreze, Cooperative
Institute for Research in Environmental Sciences
(CIRES), University of Colorado, Campus Box 449,
Boulder, CO, 80309-0449, Phone: 303-492-2963, Fax:
303-492-2468, serreze@kryos.colorado.edu
Amanda H. Lynch, CIRES, Campus Box
216, Phone: 303-492-1497, manda@tok.colorado.edu
Martyn P. Clark, CIRES, Campus Box
449, Phone: 303-492-1497, clark@vorticity.colorado.edu
Calculations of a thermal front parameter (TFP) using NCEP/NCAR reanalysis data over the period 1979Ð1998 reveal a relative maximum in frontal frequencies during summer along northern Eurasia from about 60ñ70û N, best expressed over the eastern half of the continent. A similar relative maximum is found over Alaska, which although best expressed in summer is present year-round. These high-latitude features can be clearly distinguished from the polar frontal zone in the middle latitudes of the Pacific basin and collectively resemble the summertime "Arctic frontal zone" discussed in several early studies. While some separation between high and middle latitude frontal activity is observed in all seasons, the summer season is distinguished by the development of an attendant mean baroclinic zone aligned roughly along the Arctic Ocean coastline and associated wind maxima in the upper troposphere. The regions of maximum summer frontal frequency correspond to preferred areas of cyclogenesis and to where annual precipitation is dominated by summertime contributions. Cyclones generated in association with the Eurasian frontal zone often track into the central Arctic Ocean, where they may impact on the sea ice circulation.
Development of the summer Eurasian frontal zone occurs in conjunction with a seasonal change in the large-scale circulation characterized by a zonal orientation of the isotherms. Over both Eurasia and Alaska, baroclinicity appears to be enhanced by differential heating between the Arctic Ocean and snow-free land. Frontal activity also shows an association with orography, which may help to focus the baroclinicity. Several studies have argued that the location of the summer Arctic frontal zone may be in part determined by discontinuities in energy exchange along the tundra/boreal forest boundary. However, a vegetation forcing is not required in our conceptual model.
Circulation of Atlantic derived intermediate water in the Arctic Ocean
William M. Smethie, Jr.,
Lamont-Doherty Earth Observatory of Columbia
University, PO Box 1000, 61 Route 9 W, Palisades, NY
10964, Phone: 914/365-8566, Fax: 914/365-8155,
bsmeth@ldeo.columbia.edu
Peter Schlosser, Lamont-Doherty
Earth Observatory, Department of Earth and
Environmental Engineering, and Department of Earth
and Environmental Sciences, of Columbia University,
Phone: 914/365-8707, peters@ldeo.columbia.edu
Manfred Mensch, Institut für
Umweltphysik, University of Heidelberg, Im
Heuenheimer Feld 229, Heidelberg D-69120 Germany,
manfredm@ldeo.columbia.edu
Gerhard Bönisch, Lamont-Doherty
Earth Observatory of Columbia University, Palisades,
NY 10964, boenisch@bgc-jena.mpg.de
Reinhold Bayer, Institut für
Umweltphysik, University of Heidelberg, Germany,
Phone: +49/6221-546335, Fax: +49/6221-546405,
reinhold.bayer@iup.uni-heidelberg.de
Markus Frank, Institut für
Umweltphysik, University of Heidelberg, Germany
Brenda Ekwurzel, Lawrence Livermore
National Laboratory, PO Box 808 - L-231, Livermore,
CA 94551, Phone: 925/424-3009, Fax: 925/422-3160,
ekwurzel1@llnl.gov
Samar Khatiwala, Lamont-Doherty
Earth Observatory, Phone: 914/365-8756, spk@ldeo.columbia.edu
Near surface water from the Atlantic Ocean enters the Arctic Ocean through Fram Strait and the Barents Sea. The Fram Strait Branch Water (FSBW) is clearly identified as a warm, salty subsurface water mass beneath the cold halocline within a depth range of about 200ñ600 m. The Barents Sea Branch Water (BSBW) is modified by air-sea interaction and mixing with river water and sea ice melt during its transit across the Barents Shelf. This results in it being colder and fresher, and having higher CFC and tritium concentrations than FSWB. It enters the Arctic basin from the Kara Sea, but is slightly denser than FSBW. Although it mixes with FSBW as it enters the basin, it sinks to a deeper level and is generally found between about 600 and 1500 m depth. During the 1990s a large suite of hydrographic and tracer data have been collected throughout the Arctic Ocean from a combination of icebreaker and submarine cruises which allow basin scale mapping of the spreading pathways of both of these water masses using a combination of temperature, salinity, CFC and tritium data. The time scale for this spreading and the extent of mixing that occurs along the spreading pathways can be estimated using the tracer data. Both water masses circulate around the Eurasian Basin in a cyclonic direction. The flow splits at the eastern end of the Eurasian Basin with flow paths extending across the Lomonosov Ridge along the East Siberian slope and along the Lomonosov Ridge toward Fram Strait. The time for FSBW to spread from Fram Strait along the Barents, Kara, and Laptev slopes to the eastern end of the Eurasian Basin is about 6 years and about 8 years is required for it to spread back to Fram Strait along the Lomonosov Ridge. The FSBW age along the East Siberian slope is about 8 years with no increase in age in the direction of the spreading path. This is caused by the introduction of well ventilated young shelf water into the FSBW along this spreading path. Oldest ages of 16 and 26 years are found in the central Eurasian and Canadian Basins respectively. The spreading time of BSBW from its source region to the eastern end of the Eurasian Basin is 7ñ8 years and another 8 years is required for it to spread back along the Lomonosov Ridge to Fram Strait. The spreading time for the branch that crosses the Lomonosov Ridge and flows along the East Siberian margin is about 10 years between the ridge and the North Alaskan slope. This water does not mix extensively with well ventilated shelf water as does the overlying FSBW. Since these flow patterns are based on data collected during the 1990s they are representative of flow after the boundary between Atlantic and Pacific water shifted from the Lomonosov Ridge into the Canadian Basin and these flow patterns may still be evolving with time.
The Arctic Oscillation: implications for Arctic research
John Mike Wallace, Department of Atmospheric Sciences, University of Washington, Box 354235, Seattle, WA 98195-4235, Phone: 509/543-7390, Fax: 509/685-3397, wallace@atmos.washington.edu
Abstract not available.
Are recent Arctic climate variations consistent with greenhouse projections?
John Walsh, Department of Atmospheric Sciences, University of Illinois, 105 South Gregory Avenue, Urbana, IL 61801, Phone: 217/333-7521, Fax: 217/244-4393, walsh@atmos.uiuc.edu
Control runs and greenhouse simulations from a suite of nine global climate models have provided the basis for an assessment of the climate changes projected for the Arctic as trace gas concentrations increase. Common features of the most of the model projections for the late 21st century are a strong but highly seasonal warming over the Arctic Ocean, a more modest (3ñ6°C) but less seasonal warming over the subarctic land areas, and a summertime increase in subarctic terrestrial precipitation. The models also project a general decrease of sea level pressure over the Arctic and enhanced wind-forcing of ice/ocean outflow to the North Atlantic. The warming is associated with a retreat of sea ice. Observational data for the past half-century show a seasonal warming and an increase of precipitation over the subarctic land areas. However, the observed warming appears to be largest in late winter and spring, while the model-projected warming is largest in autumn and early winter (in response to the enhanced summertime heating of the Arctic Ocean as sea ice thins). A major discrepancy in the model results and observational data is that the models' ice extent decreases most strongly in winter, while the data show a larger retreat in summer than in winter. Changes in the atmospheric circulation pattern are consistent with the observed pattern of sea ice retreat.
Composite model-derived scenarios of 21st-century change will be shown for specific locations, including the Alaskan interior, the central Arctic Ocean, and the subpolar North Atlantic. Uncertainties will be addressed in terms of the scatter among the projections from the different models.
A new environmental initiative for NSF and advances in climate modeling of the Arctic
Warren M. Washington, The National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80303, Phone: 303/497-1321, Fax: 303/497-1348, wmw@ucar.edu
The National Science Board (NSB) and NSF staff have developed a new environmental initiative. After reviewing many previous reports, holding public hearings and symposia, obtaining input from professional societies, and hearing from many individuals on the web, the NSB Environmental Task Force issued an interim report. The interim report drew many additional comments and suggestions. Finally, the final report has been issued. The NSB heard that human-caused environmental changes are producing new scientific challenges and that understanding environmental systems requires more than the standard disciplinary approach. These issues are even more critical in the Polar Regions where it is expected the changes will be among the largest. For this portion of the talk, the principal findings and recommendations will be discussed. In the second part of the talk a very brief history of climate models of the Arctic will be given with a glimpse into the future when global climate models will become global environmental models. The two aspects of the talk are connected in that 21st century environmental research will become more holistic and interdisciplinary.
The socio-demography of a native Siberian village
John P. Ziker, Department of Anthropology, Indiana University of Pennsylvania, G12 McElhaney Hall, Indiana, PA 15705, Phone: 724/357-2413, Fax: 724/357-7637, ziker@grove.iup.edu
This paper will discuss the interrelationships between demographic crisis, alcohol, and the structure of poverty in a native Siberian community in post-Soviet Russia. Increasing mortality rates and decreasing fertility rates among the Dolgan and Nganasan of Ust Avam point toward the marginalized status of these indigenous native minorities in north central Siberia. Appallingly, the risk of violent death due to homicides, accidents, and traumas is greater now than before the fall of the USSR. Analysis of death records shows that the Nganasan are being impacted more than the Dolgan. The paper illustrates the social context of the post-Soviet transition in an ethnically-mixed community of native hunter-gatherers in the Taimyr Autonomous Region, Krasnoyarskii Krai, and explores the implications of this demographic situation for renewable resource use.
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