San Jose Mercury News: Trees in old-growth forests of the western United States are dying at twice the usual rate, and scientists say climate change may be to blame. In one of the largest-ever surveys of U.S. forests, ecologists analyzed data on nearly 60,000 trees in 76 old-growth forests. Set to be published todayin the journal Science, the study reported a startling increase in the past few decades: regardless of type, size or elevation, twice as many trees are dying each year. And while death …