Given that the only place we can get climate data is in (1) the present and (2) the past, and given that the present isn't moving very quickly ("this petty pace" it was once memorably called), it's crucial for climate science to find archives of climatic information in the past. The best of these yield data for exact years. That's what my new article, "High-Precision Climate Proxies," is about. You may have heard about tree rings and the annual layers in glacial ice cores. But have you heard of varves? sclerosponges? coralline algae? The article is an up-to-date look at nine different methods. Some are tried-and-true, others are just on the bleeding edge, but all of them are pretty amazing ways of retrieving annals of the climate from times and places that humans never witnessed.
Photo courtesy Geoffrey Gilmour-Taylor via CC BY-NC-SA 2.0