Uploaded November 2016 | Updated September 2026, 42 minutes ago

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California's historic drought has killed more than 100 million trees since 2011. While some species are more vulnerable than others, even the world's largest trees, the giant sequoias, are under threat. UC Berkeley forest ecologist Anthony Ambrose describes the research he and his colleagues are conducting at the tops of these icons of the Sierra Nevada, all in an effort to protect the trees from a changing climate. Full story: bit.ly/2ge6w2u

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