Developing cold environments

Alaska is a state of the USA in the far north-west of North America, bought from Russia in 1867. The north, beyond the Brooks Range of mountains, is tundra, with permafrost; the centre and south are forest, mountains and coast.

Alaska is huge but has few people, many of them living around Anchorage and Fairbanks. Indigenous peoples, such as the Iñupiat and Yup'ik, have lived there for thousands of years.

Alaska's resources give real opportunities, but its climate and size bring challenges.

Energy: in 1968, oil was found at Prudhoe Bay on the north coast: the largest oil field in North America. Oil has paid for much of Alaska's government, and part of the money goes into a fund that pays a dividend to every resident.

Mineral extraction: Alaska has gold, zinc, lead, copper and coal. Large mines include the Fort Knox gold mine near Fairbanks and the Red Dog zinc mine in the north-west.

The problem was getting the oil out: the sea at Prudhoe Bay is frozen for much of the year.

The Trans-Alaska Pipeline carries oil about 800 miles (1,290 km) south from Prudhoe Bay to the ice-free port of Valdez. It was finished in 1977.

It was designed for the cold environment:

• Over half of it is raised on supports above the ground, so the warm oil doesn't thaw the permafrost.
• Heat pipes in the supports carry heat out of the ground, to keep it frozen.
• It runs in a zigzag, so it can expand, contract and move sideways in earthquakes. In 2002, a magnitude 7.9 earthquake moved it over 2 m sideways at the Denali Fault, and no oil was spilled.
• Gaps under raised parts let caribou cross.

Fishing: the cold seas around Alaska are rich in fish. Alaska lands about 60% of all the seafood caught in the USA by weight, including salmon, pollock, halibut and crab. Dutch Harbor, in the Aleutian Islands, lands more fish by weight than any other US port.

Tourism: visitors come for the wilderness:

• cruise ships along the south coast, past glaciers;
• Denali National Park, with North America's highest mountain;
• wildlife, such as bears and whales, and the northern lights.

Tourism and fishing bring jobs, but many are seasonal, in the summer.

• Extreme temperatures: winters are long, dark and far below freezing. Machines and vehicles need special oils and heating, and outdoor workers risk frostbite, so costs are high.
• Inaccessibility: much of Alaska has no roads. Many villages are reached only by plane or boat. The Dalton Highway, the road to Prudhoe Bay, was built for the pipeline.
• Buildings and infrastructure: a heated building thaws the permafrost beneath it, and the ground subsides. So buildings stand on piles or gravel pads, with air flowing underneath, and water and sewage pipes are insulated so they don't freeze.

• Oil has made Alaska wealthy, but output from Prudhoe Bay has fallen since the 1980s, and an oil economy depends on world prices.
• Fishing and tourism use the wilderness without destroying it, as long as they are managed, but much of the work is seasonal.
• Technology, such as the pipeline's design and buildings on piles, has overcome many challenges, but at great cost.

Judgement: the opportunities have been developed, but only with expensive engineering. As the climate warms and permafrost thaws, the challenges are growing.