Like tiny time capsules from 20,000 years ago, the minuscule bubbles trapped within Antarctic ice core samples can tell us the composition of Earth’s ancient atmosphere. Scientists use these bubbles to measure the data over time, and, as paleoclimatologist Dr. Jeffrey Severinghaus explains:

…what we’ve learned from that is that carbon dioxide is higher now than what it’s been for at least the last million years… so it’s really quite a dramatic thing that we humans have done to the carbon dioxide.

What’s In a 20,000-Year-Old Cube of Ice? Incredible information.

Joe Hanson discusses Taylor Glacier, ice cores, clathrates, how scientists study ancient air, and why we know that climate change is caused by humans in this episode of It’s Okay to Be Smart.

Watch more videos about the atmosphere, climate change, and ice including Ice Cores – Measuring Earth’s atmosphere from 20,000 years ago, 5 Things You Didn’t Know About Icebergs, and what climate change sounds like from the Amazon to the Arctic.

Bonus: Does ‘the ozone hole’ hold the secret to fixing climate change?.