Arizona Republic: Piñon pine trees, a foundation of ecosystems in the Southwest, will die faster and in greater numbers as rising temperatures from global warming intensify the effects of even short droughts. Working in the famed Biosphere 2 lab, University of Arizona researchers for the first time isolated heat as a factor in tree deaths. They found that an increase of only about 7-degrees Fahrenheit could trigger piñon die-offs five times more frequently than under existing conditions. Many climate …