Last week’s episode of NOVA Extreme Cave Diving was an interesting foray into “blue holes,” and the evidence they offer of paleo-climate. If you missed it, check the website to view it online. Similar, though less-breath taking evidence is offered in a recent paper from Yale.

This week’s Extreme Ice, provides a stunning and more in-depth review of the photographic documentation of glacial melting by James Balog, which we have mentioned before.