San Francisco Chronicle: Trees are dying faster than ever in the old-growth forests of California and the mountains of the West, a phenomenon scientists say is linked to rising regional temperatures and the destructive forces of early snowmelt, drought, forest fires and deadly insect infestations brought on by global warming. Over the past 17 years in some regions – and 25 to 37 years in others – the death rates of mature trees have doubled, the scientists said, raising concerns that the problem goes well …