Polar Bear. Credit: Stanford.

Much of what we know about the precise nature of “natural climate variability” comes from the study of geological and cryospheric archives of past climate. Cores from large coral colonies reveal sub-monthly changes in ocean conditions extending back several centuries while sediment cores from Antarctic waters tell us about past rapid changes in the Antarctic ice sheet. I’ll provide an update on what is new in the world of past climate analysis and its relevance to the global warming debate.