Published by the American Geophysical Union as part of the Special Publications Series.
Like most Earth scientists, we are intrigued and amazed by recent discoveries from ice-core and marine sediments that global climate and the ocean-atmosphere system can abruptly switch from glacial to near-interglacial temperatures within decades. Remarkably, this happened many times during and at the end of the last glacial episode, causing enormous disruptions in the global biosphere. Such discoveries are double-edged, however. Along with the excitement they prompt comes a grand challenge: their explanation. We, and others, have wondered what factors can possibly drive the climate so far and so fast. Where does the energy come from? Understanding such phenomena becomes paramount in a world with increasing concern about the potential role of humans on global climate change.