Friday, December 01, 2017 10:00 am - 12:30 pm
David Helfand / Columbia University
For few issues is the public debate conducted with so much misinformation and irrational exuberance. So now for something completely different: a dispassionate analysis of what we actually know and what we don’t yet know about climate change. In this class, Professor David Helfand carefully distinguishes facts from fiction, and physics certainties from feedback uncertainties.
Every planet’s temperature is controlled by a simple balance between the energy it receives and the energy it radiates back into space. We will examine each of the main factors affecting this balance. He will begin by exploring the astronomical phenomena that have driven climate change in the past: solar variability, changes in the Earth’s orbit and other factors over which we have absolutely no control. He will then go on to show how the composition of the Earth’s atmosphere has changed in the past and is changing today using measurements of prehistoric climate derived from tree rings and ice cores. Examining the current energy balance and what we can expect over the next few decades, we will conclude by exploding a few myths and providing a rational basis for decisions about our future.
David Helfand has been a Professor of Astronomy at Columbia University for 42 years where he served as chair of the Department for nearly half that time. He is also the former President of the American Astronomical Society and of Quest University Canada, and currently serves as Chair of the American Institute of Physics. He has received the Columbia Presidential Teaching Award and the Great Teacher Award from the Society of Columbia Graduates. He is the author of the new book, “A Survival Guide to the Misinformation Age.”