Earthâ€™s climate has passed from times characterized by huge ice caps to times when there was almost no ice at all and both Greenland and Antarctica were covered by forests. Kirk Johnson, Vice President of Research & Collections and Chief Curator, Denver Museum of Nature and Science, studies fossil leaves to refine geologic time, reconstruct ancient landscapes, track climate change, and document the evolution and extinction of species and ecosystems. For 30 years he has been chasing the 50â€“100 million year-old-forests of the last great global greenhouse period. Join him as he takes you on a journey to an entirely different Planet Earthâ€”an environment that may help us to better understand changes occurring in our own time. This Arnold Arboretum lecture will take place Monday, February 6, from 7 – 8:30 in the Hunnewell Building, as part of the Director’s Lecture Series. The event is free but registration is required. Call 617-384-5277, or visit www.arboretum.harvard.edu to place your name on the list.Â Painting below by Peter Trusler.