Shift in ozone tear leaves uncertainty
PUNTA ARENAS, Chile -- The worst of the ozone hole has pulled back once more to Antarctica this southern spring, leaving behind a shadow of uncertainty for the people living at the bottom of the Americas.
In a study with implications for how North American trees might respond to a changing climate, molecular information collected by Duke University researchers refutes a widely accepted theory that many of the continent's tree species migrated rapidly from the deep South as glaciers retreated at the end of the last Ice Age.