North America’s population. The Arctic Ocean

The Arctic Ocean is the smallest (about 14 million km²), shallowest (average depth about 1 200 m) and coldest ocean. It lies around the North Pole, surrounded by Eurasia and North America; it joins the Pacific through the Bering Strait and the Atlantic through the Greenland and Norwegian seas. Much of its floor is continental shelf and the Lomonosov Ridge runs under the middle; the deepest point is in the Fram Strait between Greenland and Svalbard (about 5 550 m; the book gives 5 527 m). The ancient Greek traveller Pytheas (325 BC) was the first to describe it. In the 18th century the “Great Northern Expedition” (1733–1743) and later Nansen, Amundsen and others explored it. The book says Peary (1909) was first at the North Pole; his claim is disputed, and in 1926 Amundsen, Ellsworth and Nobile flew over the pole in an airship. The climate is cold: –30…–40 °C in winter, with polar night and day lasting 3–6 months. Multi-year ice is 3–5 m thick, but because of global warming the summer ice area is shrinking fast. Currents bring warm Atlantic water. On the shelf there are oil, gas and fish (cod, herring); polar bears, walruses and seals live in the polar zone. Icebreakers keep the Northern Sea Route open and the navigation season is getting longer.