American Association for the Advancement of Science Arctic Division

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Plenary Session Abstracts

Index

Atmospheric Connections Across Alaskan Ecosystems

Understanding the Ocean Circulation, Ice Conditions, and Communications Among Alaska's Three Seas

Biological Coupling of Water and Benthos in Arctic Seas

Terrestrial—Marine Interactions at High Latitudes

Future Arctic Ocean and Coastal Alaska Research Needs

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Atmospheric Connections Across Alaskan Ecosystems

J.E. Overland (Pacific Marine Environmental Laboratory/NOAA, 7600 Sand Point Way NE, Seattle, WA 98115; overland@pmel.noaa.gov)
N.A. Bond and M. Wang (JISAO, University of Washington, Box 351640, Seattle, WA 98195)

Alaskan ecosystems are subject to regional fluctuations in atmospheric conditions on intraseasonal to interannual time scales, as well as the impact of hemispheric teleconnections acting on multidecadal scales. The southern portion is dominated by interannual variability in the magnitude and location in the Aleutian Low sea level pressure system. A low frequency component that connects to the North Pacific Ocean, at least in the 20th century, is the pentadecadal (50-yr) Pacific Decadal Oscillation (PDO). Physical and biological parameters for the North Pacific suggest a regime-like shift in the PDO after the 1998 La Niña, similar to those in 1925, 1947 and 1976. Northern Alaska is impacted by variability associated with the strength and location of the stratospheric polar vortex, i.e., the Arctic Oscillation (AO). The AO is strongly implicated in the warming trend of the last decade and, in particular, the tendency for earlier springs in northern Alaska. A connection of the trend in the AO to increased CO₂ and ozone processes through radiative-dynamic interactions cannot be ruled out.

A conceptual model for Alaskan climate is a combination of hemispheric/decadal scale variability accompanying the PDO and AO, interannual variability, and a long-memory stochastic component representing multiple processes on interannual to interdecadal scales. The combined impacts of these three components emphasize short-lived episodic events in the physical system which can further lead to longer-term reorganizations in the ecosystem. Pollock, coccolithophores, and perhaps crab populations are examples of the influence of this episodic event structure on ecosystems of the southern Bering Sea. Salmon in the Gulf of Alaska, caribou on the north slope, and perhaps marine mammals in the Bering Sea are examples which appear to respond to the weak low frequency aspects of climate.

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Understanding the Ocean Circulation, Ice Conditions, and Communications Among Alaska's Three Seas

W. Maslowski (Department of Oceanography, Naval Postgraduate School, Monterey, CA; maslowsk@nps.navy.mil)

The circulation in the northern North Pacific and the Bering Sea has been for a long time recognized as a key element of the global ocean thermohaline circulation and global climate. At the same time, high rates of primary productivity in this region are known to support some of the largest fish stocks and a variety of marine mammals and bird populations. A combination of these two factors determines the general requirements for interdisciplinary studies of the marine environments surrounding Alaska.

Modeling of ocean and sea ice behavior and variability between the northern North Pacific and the central Arctic Ocean has been an integral part of several coordinated research programs concerned with physical and productivity aspects of these regions. Some of the main challenges in modeling the ocean extending from the Gulf of Alaska to the Beaufort Sea have to do with the complex land geometry and bathymetry of this region. Those include Bering Strait, the passages across the Aleutian Archipelago, and the wide and shallow shelves of the Bering and Chukchi Seas. A proper representation of the annual cycle of sea ice advancement and retreat over the Bering and Chukchi Sea, its interactions with the ocean circulation over the shelves and deep basins, and the effect of such physical regimes on the local biological productivity have constituted other challenges for modelers. For these and other reasons, the three Alaska's seas, i.e. the Gulf of Alaska, the Bering Sea, and the Chukchi/Beaufort Sea have not been so far realistically accounted for in a single ice-ocean circulation model.

In this talk we present a high-resolution coupled ice-ocean model of the pan-Arctic, which resolves some of the problems with realistic representation of the ocean circulation, sea ice conditions, and communications among the Alaska's seas. Time-mean and seasonally variable ice and ocean results are emphasized. Examples of interannual and mesoscale variability and their role in inter-basin mass and property transfers are discussed. Usefulness of such a model for synthesis and integration of available observations in space and time and a feasibility of model guidance of future field campaigns is also addressed.

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Biological Coupling of Water and Benthos in Arctic Seas

J.M. Grebmeier and L.W. Cooper (Department of Ecology and Evolutionary Biology, Marine Biogeochemistry and Ecology Group, 10515 Research Drive, Suite 100, Building A, The University of Tennessee, Knoxville, TN 37932; jgrebmei@utk.edu)

Benthic processes are influenced by water column production and grazing, net carbon flux to the sediments, water temperature, sediment grain size and predator-prey relationships. Pelagic-benthic coupling can be studied on various time scales with coincident measurements of sediment metabolism as an indicator of weekly-to-seasonal carbon depositional processes and benthic faunal populations as long-term integrators of these processes. The northern Bering and Chukchi Seas have some of the richest benthic infaunal populations in the Arctic, which support a variety of bottom-feeding marine seabirds and mammals, including diving sea ducks, bearded seals, gray whales and walruses. Recent environmental changes in the Arctic, including a reduction in the extent and duration of sea ice, increased seawater temperatures, and changing salinity regimes are influencing ecosystems in the northern Bering and Chukchi seas, both spatially and temporally. Changes in the timing, extent, composition and location of annual production (both primary and secondary trophic levels) may well have rapid cascading effects to higher trophic levels in Arctic regions.

Benthic fauna in these marginal Arctic shelves are longer-lived, slower growing and tend towards higher biomass than warmer water systems, so changes to the ecosystem have broad-reaching implications for long-term impacts. Polar systems tend to have shorter food chains, so changes in lower trophic levels can cascade more efficiently to higher trophic organisms. Time series studies in the Bering Strait region indicate a decline in benthic productivity and carbon production over the last two decades, resulting in reduced faunal biomass and a change in species composition. Coincident changes seen in benthic-feeding marine mammals and seabirds in the region may well be responses to the climate-induced ecosystem change. In response to changes being observed in the northern Bering and Chukchi Seas, and the Arctic in general, time series stations for water and benthic studies have been initiated in several high productivity areas in the Bering Strait region through the Bering Strait Long Term Observatory project, which is supported by the U.S. National Science Foundation. These time series stations incorporate study sites that have been occupied south of St. Lawrence Island (SLIP stations), in the northern Bering Sea (BS stations), and southern Chukchi Sea (UTN stations) over the past two decades. In particular, these studies indicate a declining trend in carbon deposition and benthic biomass in the region, supporting evidence that the regional ecosystem is undergoing some form of environmental change. This presentation will discuss these data sets from the northern Bering and Chukchi Seas and will outline key processes at work in this region connecting the Bering Sea with the Arctic Ocean.

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Terrestrial—Marine Interactions at High Latitudes

F. Stuart Chapin, III Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000; fffsc@uaf.edu)

Interactions among the land, atmosphere, and oceans play a key role in the functioning of high-latitude regional systems. These interactions are mediated by vertical and lateral transfer of energy and materials. The hydrologic cycle provides the basic skeleton that regulates these interactions. Oceans are the ultimate source of most terrestrial precipitation. However, in summer half of terrestrial precipitation derives from recycling of water between the land and the atmosphere. The Arctic Ocean is unique in the large flux of freshwater inputs relative to ocean volume. For this reason factors controlling the partitioning between evapotranspiration and runoff on land exert a stronger control over marine processes in the Arctic than in other oceans. Global warming has increased moisture transport to high-latitude terrestrial regions and to the Arctic Ocean in amounts sufficient to affect ocean circulation. Horizontal exchange of heat through the atmosphere between land and ocean exert important controls over local climate. Coastal fog strongly influences terrestrial ecosystems, and changes in heat flux from terrestrial ecosystems to the atmosphere can alter marine air temperatures. Carbon fluxes from the land to ocean are not well quantified but may be an important component of both marine and terrestrial carbon budgets.

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Future Arctic Ocean and Coastal Alaska Research Needs

G.B. Newton (U.S. Arctic Research Commission, 4350 North Fairfax Drive, Suite 630, Arlington, VA 22203; gbnewton@plansys.com)

There can be no doubt the Arctic Ocean, Bering Sea and coastal Alaska are experiencing extraordinary environmental changes. The impacts of unprecedented warming in Alaska have been observed, for example, in the thawing of permafrost, the retreat of sea ice, an increase in precipitation, and changes in the waters of the Bering Sea and surrounding North Pacific. Since the Bering Sea provides approximately 50% of all fish consumed in the U.S., and Alaska's coasts represent 50% of the U.S. total coastline, such changes demand a national commitment and focus on Arctic research which, in turn, will have a direct bearing on the Nation's security and economic well-being.

The Arctic marine and coastal research needs of the Nation are diverse, spanning a spectrum of basic and applied sciences, as well as Arctic engineering. There is an urgent requirement to develop a comprehensive, integrated observing system to detect and monitor Arctic environmental change; the Study of Arctic Environmental Change (SEARCH) is a Pan-Arctic program that will hopefully fill this key role. There are critical needs to fully map the bathymetry and discern the basic circulation of the Arctic Ocean and surrounding coastal seas, not only to more fully understand the Arctic marine environment, but to adequately prepare for emerging, high-latitude jurisdictional issues under the UN Convention on the Law of the Sea. Future changes in Arctic sea ice will have profound implications for marine transportation, resource development (including fisheries), national security, environmental protection, and coastal erosion; each of these areas will require dedicated research, improved analysis, and more effective strategic planning. Inherent also in these research plans will be requirements to address the infrastructure needs of Alaska's coastal communities. In addition, permafrost and subsea permafrost are two components of the cryosphere of critical significance to Alaska, particularly in an era of regional warming. Renewed and enhanced engineering and basic research programs on both environments are necessary to adequately address a myriad of infrastructure issues of importance to both coastal and inland Alaska.

These research needs, and many others, are the concern of the U.S. Arctic Research Commission. The Commission is committed to creating and fostering a national vision for Arctic research for the 21st century. The Commission is also concerned with providing appropriate prominence to these research efforts in an international arena so that the U.S. can fulfill its many roles as a leading Arctic nation. Long-term commitments and evolving partnerships among federal, state, private and public sectors will be key to creating and carrying out an effective strategy for research on the Arctic Ocean and coastal Alaska. One recent example is a federal-State of Alaska partnership on creating a joint research and development plan (given impetus by Alaska Senate Joint Resolution 44).

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