Present Climate of Alaska

Figure 9.10: Mean annual temperature for Alaska.

Alaska’s climate, like that of other parts of the West, is influenced by its mountain ranges and its proximity to the ocean. Statewide averages range from a low of -20°C (-4°F) in January to a high of 11°C (52°F) in July (Figure 9.10). North of the Brooks Range, Alaska has a cold, dry, polar climate with frequent winter blizzards. Temperatures on the coast are moderated somewhat by the Arctic Ocean. Central Alaska has a dry continental climate, with a large variation between summer and winter temperatures. For example, the town of Takotna in Alaska’s interior has an average low temperature of -27°C (-17°F) in January and an average high of 22°C (72°F) in July.

Figure 9.11: Mean annual precipitation for Alaska.

A third climate area exists in the Alaskan southeast, south coast, and southwestern islands, and in west-central Alaska in the summer. These areas have moderate temperatures—an average annual temperature of about 7°C (45°F)—and high precipitation. Some areas are home to lush rainforests and receive around 500 centimeters (200 inches) of rain a year (Figure 9.11). The climate in west-central Alaska is influenced by a phenomenon that is unique in the United States: the seasonal presence of sea ice. In the winter when sea ice covers the Bering Sea, this area loses the moderating effect of open water and has a continental climate. When the sea ice melts in summer, the climate returns to a warmer, more humid maritime state.

Figure 9.12: Melting permafrost has caused a house in Shishmaref, Alaska to topple; on the Alaska Highway, permafrost subsidence caused the road to collapse under the weight of a pickup truck.

The lives of the West’s residents are tied to climate in critical ways. People in Southern California’s coastal area and Central Valley enjoy a pleasant climate, but they depend on water from elsewhere—mostly from snowmelt—for their everyday needs and for agricultural irrigation. At the time of this writing in 2014, California is in the midst of an extreme drought, and 10% of the state is in exceptional drought, the most severe possible. In Alaska, infrastructure such as roads, buildings, and oil pipelines built on permafrost is vulnerable to a warming climate, since the land surface develops bumps and pits when permafrost melts (Figure 9.12). Climate is also linked to energy resources—in the Pacific Northwest, the combination of topographical variation and abundant precipitation creates an ideal environment for hydropower.