Research Training Program

Kristopher Rhodes
Cornell College
Mount Vernon, Iowa

William DiMichele, Ph.D.
Supervising Scientist
Department of Paleobiology

"I wouldn't have guessed that
fossil plants are such wonderful
tools, recording large scale
climate trends as well as
tracking small scale
environmental changes."

The Climate of the Permian: Fossil Plants as Tools

Global climate change is one of the "hottest" problems facing society today. Computer-based climate models are an important and valuable tool for determining actual climate patterns - but, unfortunately, these models can not make predictions about the most important aspect of climate to us: plant and animal responses to climate change. Climate change similar to what we are facing today has occurred before in the history of life, millions of years ago. As such, examining the fossil record can provide insight into our current problem. During the Permian period, 250-300 million years ago, the Earth went through a transition from cool-to-warm (so-called "icehouse" to "greenhouse"). Average global temperatures rose from 12° C to 22° C. With today's average global temperature near 14.5° C and rising, potentially carrying us out of our current cool-Earth climate mode, our best record of a similar climatic event may lay in the Permian. During Permian time, the climate of what is now Texas transitioned from warm and wet to cool and dry. 280 million years ago the landscape was dominated by plants adapted to dry conditions, such as conifers, with intermittent dominance of plants adapted to wet conditions. Occasionally there were also locations where wet and dry plants seem to be mixed together. This phenomenon is poorly understood. The goal of this research was to better understand these mixed floras. Individual fossil samples were examined to determine if the wet and dry elements occurred simultaneously, or were separated by very short periods of time not captured in the scale of previous analyses. Currently, the research suggests that the wet and dry plants were discrete, occurring during very briefly separated periods of time. This implies that there were climatic pulses, analogous to recent periods of glacial and interglacial global climate change, during the Permian period some 300 million years ago, within the longer-term trend toward warming and drying.

This research was supported by a grant from the NMNH Office of the Director.

Letter of gratitude