Dr. Francis Macdonald, Dr. Mark Schmitz and Dr. James Crowley are co-authors on a research paper published March 5 in Science, the academic journal of the American Association for the Advancement of Science. Called “Calibrating the Cryogenian,” the article’s underlying study of dramatic changes in Earth’s climate more than 700 million years ago was generated by lead author Francis Macdonald, an assistant professor in the Department of Earth and Planetary Science at Harvard University. Macdonald was a visiting scientist in early 2009 in Boise State’s Isotope Geology Laboratory. The study was sponsored by the Polar Continental Shelf Project and NSF Geobiology and Environmental Geochemistry Program grant EAR 0417422.