Climate variability and physical forcing of the food webs and the carbon budget on panarctic shelves Eddy Carmack a, * , David Barber b , Jens Christensen c , Robie Macdonald a , Bert Rudels d , Egil Sakshaug e a Department of Fisheries and Oceans, Institute of Ocean Sciences, 9860 West Saanich Road, Sidney, BC, Canada V8L 4B2 b Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2 c Danish Meteorological Institute, DK-2100, Lyngbyvej 100, Copenhagen Ø, Denmark d Finnish Institute of Marine Research, PO PL33, FI-00931 Helsinki, Finland e Trondhjem Biological Station, Norwegian University of Science and Technology, Bynesveien 46, N-7018 Trondheim, Norway Available online 17 November 2006 Abstract Brief overviews of the Arctic’s atmosphere, ice cover, circulation, primary production and sediment regime are given to provide a conceptual framework for considering panarctic shelves under scenarios of climate variability. We draw on past ‘regional’ studies to scale-up to the panarctic perspective. Within each discipline a synthesis of salient distributions and processes is given, and then functions are noted that are critically poised and/or near transition and thereby sensitive to climate variability and change. The various shelf regions are described and distinguished among three types: inflow shelves, interior shelves and outflow shelves. Emphasis is on projected climate changes that will likely have the greatest impact on shelf-basin exchange, productivity and sediment processes including (a) changes in wind fields (e.g. currents, ice drift, upwelling and downwelling); (b) changes in sea ice distribution (e.g. radiation and wind regimes, enhanced upwelling and mixing, ice transport and scour resuspension, primary production); and (c) changes in hydrology (e.g. sediment and organic carbon delivery, nutrient supplies). A discussion is given of the key rate-controlling processes, which differ for different properties and shelf types, as do the likely responses; that is, the distributions of nutrients, organic carbon, freshwater, sediments, and trace minerals will all respond differently to climate forcing. A fundamental conclusion is that the changes associated with light, nutrients, productivity and ice cover likely will be greatest at the shelf-break and margins, and that this forms a natural focus for a coordinated international effort. Recog- nizing that the real value of climate research is to prepare society for possible futures, and that such research must be based both on an understanding of the past (e.g. the palaeo-record) as well as an ability to reliably predict future scenarios (e.g. validated models), two recommendations emerge: firstly, a comprehensive survey of circumpolar shelf-break and slope sed- iments would provide long-term synchronous records of shelf-interior ocean exchange and primary production at the shelf edge; secondly, a synoptic panarctic ice and ocean survey using heavy icebreakers, aircraft, moorings and satellites would provide the validation data and knowledge required to properly model key forcing processes at the margins. Ó 2006 Elsevier Ltd. All rights reserved. 0079-6611/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.pocean.2006.10.005 * Corresponding author. Tel.: +1 250 363 6585. E-mail addresses: carmacke@dfo-mpo.gc.ca (E. Carmack), dbarber@ms.umanitoba.ca (D. Barber), jhc@dmi.dk (J. Christensen), macdonaldrob@dfo-mpo.gc.ca (R. Macdonald), bert.rudels@fimr.fi (B. Rudels), egil.sakshaug@vm.unit.no (E. Sakshaug). Progress in Oceanography 71 (2006) 145–181 Progress in Oceanography www.elsevier.com/locate/pocean