Researchers Just Sampled 1.4-Billion-Year-Old Air—and It’s Not What They Expected
Gizmodo | 7/1/26 | Margherita Bassi

Researchers have retrieved samples of 1.4 billion-year-old air from ancient crystals …

The next time I’m in a fancy bar, I’m going to order that author’s name, and see what I get.

— The bartender will be too proud to admit he doesn’t know what I am talking about — proving that we have something in common.

Over a billion years ago, a lake in modern-day Ontario evaporated. During the evaporation, some of the resulting brine was captured within halite crystals along with air bubbles—precise records of our early atmosphere’s makeup. Extracting accurate readings from these fluid inclusions, which have both air and brine (salt water), is difficult, however—some gases, including oxygen and carbon dioxide, act differently based on whether they exist in water or air. As such, it’s been challenging to precisely measure the gases in their original state.

The team solved the problem using a method previously developed by Park, uncovering that around 1.4 billion years ago, during the Mesoproterozoic era (1.6 to 1.0 billion years ago), Earth’s atmosphere contained ten times more carbon dioxide than today.…the Mesoproterozoic climate was more mild than researchers theorized.

The atmosphere also had 3.7% of today’s oxygen levels.