The Strange Reason This Glacier Bleeds Red | NOVA PBS

A glacier in Antarctica's Dry Valleys oozes a rust-red liquid that looks like blood, and hosts Caitlin Saks and Arlo Pérez travel out to find out why. The answer involves ancient trapped seawater, iron oxidation, and microbes that survive with almost no oxygen or light.

Why it's free: Free on NOVA PBS's own channel; GBH first ran it on PBS Terra and NOVA republished it here.