Ideas The natural — and unnatural — history of air on Earth
Sep 25, 2025
Gabriel Walker, a climate scientist and author, dives into the transformative history of Earth’s atmosphere, discussing how air shapes life. Sam Keane, a renowned science writer, adds depth by exploring the stages of atmospheric evolution and the rare occurrence of oxygen. The conversation highlights the dramatic impacts of human activity on air quality and climate, from greenhouse gas effects to past mass extinctions. They consider future adaptations, from carbon removal strategies to innovative geoengineering solutions, revealing a pressing need to rethink our relationship with air.
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We Live In An Ocean Of Air
- Air is a tangible, heavy substance that surrounds us like an ocean we live inside.
- Understanding air as a physical medium reveals unseen currents and processes above us.
Four Ages Of Earth's Atmosphere
- Earth has undergone four distinct atmospheres driven by geology and life.
- Oxygen rose last via photosynthesis and transformed the planet dramatically.
Oxygen: Life's Fuel And Threat
- Oxygen is highly reactive and once nearly exterminated early life.
- Its reactivity also enabled large, multicellular animals by powering efficient metabolism.
