Stalagmites from a Missouri cave have yielded a clear picture of climate and vegetation change in the mid-continental region during the millennia leading up to the last ice age (75,000 to 25,000 years ago), a time period for which such data have been sketchy. The records show that average temperature fluctuations of four degrees C were associated with profound changes in vegetation, including a sharp shift from prairie to forest 55,000 years ago, when temperatures fell and ice sheets began to grow. The study, to be published Friday (Dec. 4) in the journal Science, reveals the value of stalagmites in reconstructing past climate, said lead author Jeffrey Dorale, a graduate student in geology at the University of Minnesota.
"It hasn't been clear how climate and vegetation changed between 120,000 years ago, when conditions were similar to today, and 20,000 years ago, when the last Ice Age was at its peak," said Dorale. "Much of the data comes from the oceans, and while that's good in determining global patterns it's less helpful in figuring out local and regional climate histories."
