Word: droughts
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...knows when the drought will end. Scientists believe this dry spell, which has plagued a broad swath of the West since 1999, is more typical of the region than its 60 million inhabitants would care to admit. As Charles Ester, chief hydrologist for Arizona's Salt River Project, a major provider of water and electricity, puts it, "What we took as a period of normal rainfall in the past century was actually a period of abundance...
...swimming pools and hot tubs, not to mention such modern necessities as dishwashers and flush toilets and the hydropower that keeps refrigerators and home computers humming. Caught off guard, political leaders and water-resource managers have been turning to scientists for help. What do researchers know about patterns of drought in North America? What do they think occurred in the mid-1990s when a big chunk of the West abruptly veered from wet to dry? And do they believe that the current shortfall of precipitation is just a temporary dry spell or an ominous realignment of the earth's climate...
This is important because in the West most precipitation falls as snow at higher elevations. Thus, a city like Reno, Nevada, gets, on average, just over 7 in. of precipitation a year, vs. some 70 in. at the top of nearby Mount Rose. During the 1950s drought, for example, a very large portion of the West, along with a big chunk of the Southeast and Great Plains, experienced long-term shortfalls of both winter snows and summer rains. "This is the kind of drought we worry about a lot," says Betancourt--and it's the kind of drought that...
...Drought is more than a precipitation deficit," observes University of Washington climatologist Philip Mote. The real problem, he says, "is that you don't have as much water as you'd like at a given point in time." And that goes for plants as well as people. For accompanying an earlier snowmelt, scientists note, is an earlier start to the growing season, which means that the demand for water by forests, marshes and grasslands--not to mention agricultural crops, lawns and putting greens--is bound to rise. In this context, a "normal" amount of precipitation may not be sufficient...
Indeed, the bark-beetle infestations that are killing trees across the West are attributed to drought (complicated by decades of fire suppression that have resulted in an overgrowth of trees). And nowhere is the beetle infestation worse than in the mountains of Southern California, whose stressed-out forests harbor hundreds of thousands of beetle-killed trees. These trees, some with rust-colored needles still hanging from their limbs, serve as standing fuel for fires, and an effort is under way to remove as many as possible along the roads inhabitants in the San Jacinto, San Bernardino and San Gabriel mountains...