Saturday, December 29, 2007

In California, climate change will transform the land, lifestyles

Summit Daily News, via AP: …As the global climate warms, California’s one-of-kind geography and the lifestyle it has made famous will not escape the consequences.…Many of the scientific predictions are gloomy. Some already are coming true.

Among the earliest and most noticeable casualties is expected to be California’s ski season. The snow is likely to continue but is expected to fall for a shorter period of time and melt more quickly. That could shorten the ski season by a month even in wetter areas and perhaps end it in others.

...Because California is a coastal state with myriad microclimates, predicting exactly what will happen across a land mass a third larger than that of Italy by the end of the century is a challenge. But through a series of interviews with scientists who are studying the phenomenon, a general description of the state’s future emerges.

By the end of the century, temperatures are predicted to increase from 3 degrees to as much as 10 degrees Fahrenheit statewide. That could translate into even less rainfall across the southern half of the state, which already is under pressure from the increased frequency of wildfires and relentless population growth.

…Farther north, where wet, cold winters are crucial for the entire state, warmer temperatures will lead to more rain than snow in the Sierra Nevada and faster melting in the spring. Because 35 percent of the state’s water supply is stored annually in the Sierra snowpack, changes to that hydrologic system will lead to far-reaching consequences for California and its ever-growing population.

Some transformations already are apparent, stretching from the Sierra high country to the great valleys that have made California the nation’s top agricultural state. The snowline, as it is in many other alpine regions around the world, is receding. Throughout the 400-mile-long Sierra, trees are under stress, leading scientists to speculate that the mix of flora could change significantly as the century grows hotter.

The death rate of fir and pine trees has accelerated over the past two decades. In the central and southern Sierra, the giant sequoias that are among the most massive living things on earth might be imperiled. “I suspect as things get warmer, we’ll start seeing sequoias just die on their feet where their foliage turns brown,” said Nate Stephenson, a U.S. Geological Survey ecologist who is studying the effects of climate change in the Sierra Nevada. “Even if they don’t die of drought stress, just think of the wildfires. If you dry out that vegetation, they’re going to be so much more flammable.”

Because the Sierra snowpack accounts for so much of California’s water supply, the changes could lead to expensive water disputes between cities and farmers. Without consistent water from rivers draining the snowmelt, farmers in the Central and Salinas valleys could lose as much as a quarter of their water supply.

What will happen along California’s famed coastline will affect the rest of the state, yet is among the biggest unknowns. …Changing seas will present trouble for much of the state’s land-dwelling population, too. A sea level rise of three to six feet will be enough to inundate the airports in San Francisco and Oakland. Many of the state’s beaches are expected to shrink as sea levels rise and winter storms carry away sand. “If you raise sea level by a foot, you push a cliff back 100 feet,” said Jeff Severinghaus, professor of geosciences at the Scripps Institution of Oceanography in San Diego. “There will be a lot of houses that will fall into the ocean.”

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