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.