Canary

Daring to seek Earth's history contained in glaciers atop the tallest mountains in the world, Dr. Lonnie Thompson found himself on the frontlines of climate change—his life's work evolving into a salvage mission to recover these priceless historical records before they disappear forever.

This is a current release, so it is not free to download. The legal options are renting, buying or streaming it on a service you already pay for. Every link goes to the store that holds the rights.