This is part of the Arctic Climate Impact Assessment Lead Author: Gordon McBean. Contributing Authors: Genrikh Alekseev Deliang Chen Eirik Førland John Fyfe Pavel Y. Groisman Roger King Humfrey Melling Russell Vose Paul H.Whitfield

2.3.1. Geography

The Arctic Ocean forms the core of the marine Arctic. Its two principal basins the Eurasian and Canada are more than 4000 m deep and almost completely landlocked (Fig. 2.4).Traditionally the open boundary of the Arctic Ocean has been drawn along the Barents Shelf edge from Norway to Svalbard across Fram Strait down the western margin of the Canadian Archipelago and across Bering Strait[2]. Including the Canadian polar continental shelf (Canadian Archipelago) the total ocean area is 11.5 million km2 of which 60% is continental shelf. The shelf ranges in width from about 100 km in the Beaufort Sea (Alaska) to more than 1000 km in the Barents Sea and the Canadian Archipelago. Representative shelf depths off the coasts of Alaska and Siberia are 50 to 100 m whereas those in the Barents Sea East Greenland and northern Canada are 200 to 500 m. A break in the shelf at Fram Strait provides the only deep (2600 m) connection to the global ocean.

Alternate routes to the Atlantic via the Canadian Archipelago and the Barents Sea block flow at depths below 220 m while the connection to the Pacific Ocean via Bering Strait is 45 m deep. About 70% of the Arctic Ocean is ice-covered throughout the year. Like most oceans the Arctic is stratified with deep waters that are denser than surface waters. In a stratified ocean energy must be provided in order to mix surface and deep waters or to force deep-water flow over obstacles. For this reason seabed topography is an important influence on ocean processes. Sections 6.3 and 9.2.2 contain detailed discussions of the Arctic Ocean and sea ice.

The term “marine Arctic” is used here to denote an area that includes Baffin Hudson and James Bays; the Labrador Greenland Iceland Norwegian and Bering Seas; and the Arctic Ocean.This area encompasses 3.5 million km2 of cold low-salinity surface water and seasonal sea ice that are linked oceanographically to the Arctic Ocean and areas of the North Atlantic and North Pacific Oceans that interact with them. In this region the increase in density with depth is dominated by an increase in salinity as opposed to a decrease in temperature. The isolated areas of the northern marine cryosphere namely the Okhotsk and Baltic Seas and the Gulf of St. Lawrence are not included in this chapter’s definition of “marine Arctic”.