Supplementary material to “Past, Present, and Future: A Science Program for the Arctic Ocean Linking Ancient and Contemporary Observations of Change Through Modeling”

Bernard Coakley, Geophysical Institute, University of Alaska Fairbanks; Henrietta N. Edmonds, University of Texas at Austin; Karen Frey, Graduate School of Geography, Clark University, Worcester, Mass.; Jean-Claude Gascard, University Pierre et Marie Curie, Paris; Jacqueline M. Grebmeier, Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville; Heidemarie Kassens, Leibniz-Institut fuer Meereswissenschaften, Kiel, Germany; Jörn Thiede, Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany; Carolyn Wegner, Leibniz-Institut fuer Meereswissenschaften, Kiel, Germany

Citation:
Coakley, B., H. N. Edmonds, K. Frey, J.-C. Gascard, J. M. Grebmeier, H. Kassens, J. Thiede, and C. Wegner (2007), Past, present, and future: A science program for the Arctic Ocean linking ancient and contemporary observations of change through modeling, Eos Trans. AGU, 88(28), 287. [Full Article (pdf)]

The 2nd International Conference on Arctic Research Planning (ICARP II) was a process that led to the development of science and action plans by 12 working groups (WG) that spanned the full range of arctic studies of culture, society, atmosphere, land, ice and water. The reports from these varied working groups and documents developed at the meeting, which was held in Copenhagen, Denmark from 19 to 23 November, 2005, are available at http://www.icarp.dk/.

To build on the ICARP II effort, chairs and young scientists from the working groups, representatives of the sponsoring agencies and members of the steering group met recently in Potsdam, Germany from November 19–21, 2006 to use the rationale laid out in the working group reports to focus future science activity in the post International Polar Year environment.

The original marine working groups were, unavoidably, somewhat arbitrarily divided into shelf, margin/gateways and deep basin regions (Figure 1). The membership of each group reflected differences in scientific disciplines currently focused on the different regions. The connectivity and overlapping concerns of the sub-regions were reflected in redundancies between the WG reports. At the same time, gaps appeared in the WG reports where coverage lay between groups and was addressed by neither. In Potsdam, these three groups, the Deep Basin (WG 4), Margins and Gateways (WG 5) and Shelves (WG 6), met together to come up with a unified science plan derived from their reports.

The Arctic Climate Impact Assessment (ACIA, 2005) provided the representatives in Potsdam with a partial basis and cause for urgency in developing joint, cross-disciplinary studies. The rapid rate of change in the Arctic Ocean, the lack of baseline data to characterize change and the unknown history of the basin all combine to make the magnitude of future changes and the social and ecological consequences of these changes impossible to predict.

A consensus was obtained between WGs based on shared priorities, such as transport and exchange at interfaces—coast-ocean, shelf-slope, deep-sea, ocean-atmosphere—that extend across the artificial boundaries imposed by the divisions in their subject matter. This consensus forms the basis for a coordinated science program to monitor the Arctic Ocean and reconstruct its history. Our unified science plan for the next ten years advocates extensive, autonomous monitoring of the ocean, supported and augmented by deep historical studies based on scientific ocean drilling.

Improved monitoring of the Arctic Ocean through autonomous data acquisition and time-series studies is the first component of our proposed program. Understanding of the active processes in the Arctic Ocean is being built on monitoring at sea and on land at strategic sites. Synoptic observations collected by satellites, buoys, gliders, moorings and through cabled seafloor observatories will make it possible to understand the active processes on Arctic Ocean margins. These data will document change at seasonal, annual and, eventually, decadal scales. Ultimately it will be possible, through the accumulation of synchronized observations, to understand exchange through the gateways, across the shelf-basin interface and throughout the basin.

The second focus is on scientific drilling to reconstruct the tectonic history of the Arctic Ocean and recover the paleoceanographic records. The tectonic history of the Arctic Ocean is critical to setting the physical boundary conditions that restrict and enable oceanographic processes, through the opening and closing of the various gateways that shape ocean circulation. The paleoceanographic record in the basin, gateways and slope regions preserves the transition from the warm high CO2 environment of the Paleocene to the ice-dominated ocean we know today. These records are critical to understanding the consequences of high atmospheric CO2 and calibrating predictions of the future consequences of accumulating greenhouse gases.

Both of these objectives will require a sequence of activities, building through successive cruises and studies, to acquire the information necessary to bring these programs to fruition. Site surveys will be necessary to identify critical locations for monitoring and for seafloor sampling by drill. Technological development is required to make the most of limited ship time and spatially restricted monitoring of the ocean, seafloor and ice. While these common elements link the recommendations of the WGs, there are independent recommendations from each.

Working Group 4—The Deep Basin of the Arctic Ocean

WG 4 had as it charge to consider the science necessary to understanding the deep central Arctic Ocean and its contained ridges. While the basin form is fairly well known today, exploration of the Arctic Ocean is ongoing. Our view of the basin is focused by the bathymetry, gravity and seismic reflection data that have been collected and released by the US Navy over the last decade, but our understanding of the basin’s sub-seafloor structure and history is incomplete. Acquiring more multi-channel seismic reflection data will be necessary to map the structures and select sites for scientific drilling. Drilling is the only way to date events and structures in the basin and collect the records of ancient climates preserved beneath the seafloor.

The initial focus for drilling should be the condensed sections on the basin highs to obtain complete, long-term records of the basin history, including the Mesozoic history of the Amerasian Basin, which is almost completely unknown. In the short term, these objectives may best be served by drilling on the Chukchi Plateau.

Arctic science depends on access. Despite rapidly declining sea ice extent observed over the last two decades (Figure 2), there are regions that are not accessible by icebreakers in any season. Other areas are seasonally accessible. Study of the complex, heterogeneous, variable processes in this basin requires continuous access to the water column, the ice surface and the seabed. Autonomous data acquisition is the only way to acquire data of sufficient density in the critical regions.

Working Group 5—Arctic Margins and Gateways

Arctic gateways regulate many aspects of the Arctic Ocean and the global climate system. The margins are the active transformation sites along oceanic boundary pathways and the source of water, carbon and sediment transferred from the shelves to the deep basins. A fundamental objective of WG5 is to understand how Arctic margins and gateways regulate the physical and biogeochemical processes in the Arctic that are linked to sea-ice dynamics, air-sea interactions, the freshwater balance, and associated ecosystem dynamics. The shelf-break is a focal zone for evaluating system responses in terms of changing sea-ice cover, boundary current dynamics, and shelf-basin exchange. This information is necessary to understand how ecosystems are adjusting to change.

The WG5 science plan proposes a coordinated, international research strategy to include contemporary oceanographic and biological studies along select section lines across the slope as well as mooring emplacements in key Arctic regional areas (Figure 1). Longer-term paleoceanographic studies should also be collected at select sites, including geophysical aspects to establish the detailed tectonic, geodynamic, sedimentary and paleo-topographic histories of the margins and gateways. These field campaigns require coordination with high-resolution process and large scale modeling studies to optimize observations and enable synthesis of data to understand Arctic Ocean variability across broad time scales. Time-series data collections (autonomous and ship-based) will enable us to evaluate the role of gateways and slope regions in climate change and the associated ecosystem response. This proposed framework would also leverage ongoing and planned field operations for emplacement of a long-term observatory network to track processes at the margins and gateways that are both influencing and responding to Arctic environmental change.

Working Group 6—Arctic Shelf Seas

WG 6 aims to understand the Arctic shelf environments in terms of a changing Arctic. Over the past decade, evidence has accumulated that the Arctic is undergoing sweeping change. Most of these changes have already directly manifested on shelf environments. If they continue, as implied by climate models, they will have major implications for circum-Arctic ecology and for human activities. Although the mechanisms amplifying or damping the potential changes are not well understood, effective modeling of the entire system across disciplines over the next five decades requires a deeper understanding to project their influence over the global climate. With respect to increasing levels of shipping, resource exploitation, and traditional subsistence activities in arctic shelf seas a close coordination of multidisciplinary circum-arctic activities is essential and strongly required to predict changes and improve future assessments.

Virtually unexplored territories are subsea permafrost regions beneath the arctic shelf seas. Increasing air and water temperatures over most of the arctic shelves are likely to accelerate thawing of coastal and subsea permafrost along the Siberian shelf seas in particular. A considerable amount of organic carbon is stored in the upper layer of permafrost and gas hydrates are expected within and beneath the subsea permafrost. Thawing of permafrost could release large quantities of greenhouse gases into the atmosphere, further increasing global warming.

The scientific approach for the study of the Arctic shelf seas is driven and defined by the overarching hypothesis that past and predicted future changes in the Arctic shelf regimes will result in an increase of transport across the shelves in the broadest sense (i.e., fluxes of energy, matter, biota and species, goods and natural resources etc.). This enhanced cross-and along-shelf transport (Figure 3) will tie the Arctic system closer to lower latitudes through oceanic and atmospheric processes, but also through political, societal and economic linkages. A multidisciplinary synchronous circum-Arctic approach in cooperation with WG 4 and 5 (transects from the coast across the shelf into the deep Arctic Basin) is required. Optimally, expeditions should be carried out during all seasons and augmented by process studies via time-series measurements by one-year or multi-year seafloor observatories. Technological development is needed for autonomous and event-driven sampling methods in the highly variable Arctic shelf system and for biogeochemical sensors which can be implemented into the long-term mooring stations.

A Science Program for the Arctic Ocean

While the members of the three marine working groups spanned the full range of disciplines working in the Arctic Ocean today, there was a surprising consensus on the highest priority science objectives. Understanding contemporary processes and variations at the days to decades scale at dispersed sites across the Arctic Ocean margins and basin is the highest priority for the oceanography, biology and sea ice communities. Consistently monitoring key locales and circulation chokepoints (e.g., gateways) with autonomous instruments is the only hope of establishing how climate change is advancing through various systems in the Arctic.

While a well-structured monitoring program could expose the synoptic changes in processes, study of the Arctic Ocean at long time scales is hampered by short historical records and substantial uncertainties about Mesozoic and Cenozoic paleoceanography and basin history. Study of the basin at time scales of hundreds to tens of millions of years can only be accomplished through a systematic program of scientific drilling. These records would also span the time of the last high pCO2 environment, which would provide a critical analog for the present anthropogenically driven climate changes.

The objective of ICARP II was to define a science plan for the Arctic for the next ten years. The two programs highlighted here will require substantial technological development and site preparation over this time. We anticipate that these projects will build on existing programs (eg. SEARCH), expeditions (eg. ACEX drilling, SBI, CASES, NABOS), planning efforts for scientific drilling (eg. NAD, IODP and the dedicated drill ship, the Aurora Borealis), and existing monitoring projects (NPEO, DAMOCLES, BGO, BSEO) advancing through workshops, working groups, independent proposals and international expeditions as well as the concentrated activities of the International Polar Year.

The Arctic Ocean is the missing piece for any global model. Records of processes at both long and short time scales will be necessary to predict the future evolution of the Arctic Ocean through what appears to be a period of rapid climate change. Ocean monitoring is impoverished without the long time scale records available from paleoceanography and the boundary conditions that can be obtained from marine geology and geophysics. The past and the present are the key to our ability to predict the future.

Figure 1. Distribution of regional areas considered by the marine working in the ICARP II science plans. Bathymetric image obtained from IBCAO website (Jakobsson et al. 2000).

Figure 2. Changing ice limits.

Figure 3: Dirty sea ice in the Arctic Ocean. An efficient transport mechanism for sediments, nutrients, and contaminants linking coasts, shelves, and slopes with the deep basins.

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