8. The Pacific Region

Because it borders the Pacific Ocean, coastal California southward of approximately 40°N latitude experiences a mild and very pleasant Mediterranean climate. In fact, many people believe the Mediterranean to be the world’s most pleasant environment. This is one reason why “sunny Southern California” has been a primary magnet for migration for many decades. Summer temperatures rarely reach into the 80s°F (mid-20s°C), and freezing temperatures are unknown in many locations. Severe storms are uncommon. Despite the summer drought and lack of storms, much of the region receives 30 to 50 inches (75 to 125 centimeters) of rainfall annually. Mediterranean weather is unique in one major respect—it is the only climate that experiences summer drought. Weeks can pass during the summer months without a cloud appearing in the sky. Natural vegetation is chaparral scrub and grassland, with many eucalyptus species that were introduced from Australia during the mid-1800s. Native wildlife has largely succumbed to human population growth and destruction of natural habitat.

Coastal northern California and the Alaskan panhandle have a soggy West Coast marine climate that is moist and temperate. Compared to locations at comparable latitudes, the region’s summer temperatures are considerably cooler and winter temperatures much warmer. Some locations may go years without experiencing snowfall, something unheard of east of the Cas­cades. The area that lies west of the mountains is the wettest portion of the continental United States. Warm moisture-bearing winds that blow in from the Pacific are forced aloft over moun­tains soon after they reach the coast. Rising air cools, condenses, and is ripe for precipitation. Cities such as Seattle, Washington, can go weeks at a time without sunshine. Because of the constant high humidity and frequent drizzle, it is often jokingly said that residents of the region do not die, they just rust away! The wettest spot in the continental United States is in northwestern Washington’s Olympic Peninsula, where up to 150 inches (380 centimeters) of moisture falls each year. Several locations in the Cascades and Sierra Nevada receive several hundred inches of snowfall each winter. The snowfall record belongs to Washington’s Mount Baker Ski Area. During the winter of 1998–1999, it was buried beneath an incredible 1,140 inches, or 95 feet (2,896 centimeters, or 29 meters), of snow!

This region is home to some of North America’s most remarkable forests. Reliable moisture and high relative humidity, including frequent fog, are ideal for tree growth and fire suppression. Until recent years, when the harvest was sharply reduced as a result of environmental issues, the largely needle-leaf evergreen forests of the Pacific Northwest provided most of the country’s high-quality lumber. California alone can boast of three enviable world records held by trees growing there. The world’s tallest tree is a redwood in an undisclosed (for protection) location in northern California’s Redwood National Park. The towering giant, named Hyperion, reaches a height of 379 feet (115.5 meters). The state also lays claim to the world’s largest tree by mass. The General Sherman Tree in Sequoia National Park has a volume of 52,500 cubic feet (1,486.6 cubic meters) and a base diameter of 36.5 feet (11.1 meters). “Methuselah,” a nearly 4,800-year-old bristlecone pine located in California’s White Mountains, is not only the world’s oldest tree, it is believed to be Earth’s oldest living thing.

Despite its largely humid tropical climate, Hawaii has an amazing diversity of microclimatic conditions and resulting ecosystems. For a small island, Maui almost certainly holds some kind of environmental record. One can stand in a beautiful Mediterranean-type landscape on the slope of 10,000-foot (3,050-meter) Mount Pu’u’ Ula’ula and be within roughly 6 miles (10 kilometers) of nearly all of Earth’s ecosystems—from steaming tropical rain forest to water-starved desert and subpolar conditions. Only a polar ice cap condition is missing! An equally amazing extreme exists on the island of Kaua’i. There, one can stand in a desert environment with scant vegetation dominated by grasses, scrub plants, cacti, and irrigated agriculture. Only several miles away, rain falls almost constantly over Mount Waialeale, making it the world’s wettest spot with an average 460 inches (168.5 centimeters) of rainfall each year! This anomaly is created by the orographic effect (rain) and rain shadow (aridity).

Much of Alaska experiences short, cool summers and long, often severe winters. Only along the southern coast are temperatures moderate. The capital, Juneau, and largest city, Anchorage, are considerably warmer during the winter months than are many cities in the northern “Lower 48” (as Alaskans refer to the region). Inland, temperatures can plummet to -78°F (-61°C), but also soar to 100°F (40°C). Moisture is adequate throughout the year, although much of it comes in the form of snow that can fall during any month in some locations. Much of the state supports a taiga (or boreal) forest composed of dense stands of larch, pine, spruce, and aspen. Only in the far north does woodland give way to the tundra. Here, shallow soils and a very short growing season support a stunted ecosystem dominated by mosses, lichens, clump grasses, and hardy flowering plants. Moose, bears (black, brown, including the huge Kodiak and grizzly, and polar), deer, and caribou thrive here. Marine life includes whales, seals, walrus, and much of the seafood (fish and crab) enjoyed by Americans.