2007-2008 AAPG Distinguished Lecture – December 7, 2007

Title: Crocodiles in Greenland and Hippos in London: A Fossil-Fueled Tour of Past and Future Climates

Speaker: Kirk Johnson, Denver Museum of Nature and Science

Date: December 7, 2007

Publication: The Outcrop, December 2007, p. 30

The earth’s climate is driven by the interaction of solar energy with land, sky, and oceans. While this has always been the case, shifting positions of continents and the ever-changing chemistry and currents of oceans and air have created a world with a complex history. Most of Earth history has occurred during greenhouse conditions when there were no polar ice caps. Less common were icehouse conditions when there were polar ice caps that waxed and waned between glacial and interglacial periods. This history is written in stone and told by fossils. Fossil plants from 50 million years ago show that the polar regions were ice free and densely forested and that tropical rainforests reached middle latitudes. The talk will take you from the Amazon Basin to the High Arctic and into Deep Time as he explains our planet’s history by visiting fossil sites on different continents and using them to reconstruct lost worlds, extinct biomes, and ancient climates. Recent advances in geochronology allow the fossil record to be dated with increasing precision, thus providing some context for understanding climate change and global warming in the present and future.