While some climatologists study tree rings to decode the history
of climatic change, others are scrutinizing a different kind of
tree record: century-old forest photographs. By comparing
contemporary photos with shots from a century ago, "you can
literally see that trees are leafing out and the plants are
flowering earlier now," says [Richard] Primack, of Boston
University. [DISCOVER Magazine] In a study published in the
American Journal of Botany, Primack and his colleague, Abraham
Miller-Rushing, discovered something interesting after analyzing
286 century-old photographs of Concord, Massachusetts, and
Boston's Arnold Arboretum: The leaves are coming out 10 days
earlier on average than they did a century ago. "These kinds of
changes are already being seen in Boston, and they will be seen
in the rest of the United States in the next 100 years," he
says. "We're going to see enormous changes in the distribution
of plants and animals, agricultural patterns, and patterns of
rainfall." Some plants may even begin