Decouple Carbon Dioxide: Earth's Thermostat
Sep 22, 2025
Join award-winning science writer Peter Brannen, who specializes in deep-time geoscience, as he explains the 4.5 billion-year saga of carbon dioxide. Discover how CO2 shaped early life and the planet's evolution through events like Snowball Earth and the Permian extinction. Hear about the role of fossil fuels in creating an oxygen-rich atmosphere and how climate shifts influenced human evolution. Brannen also dives into the significance of small CO2 changes and early human impacts on today's climate.
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CO2 As Earth's Central Thermostat
- CO2 is central to Earth's habitability because it powers photosynthesis and regulates temperature through the carbon cycle.
- The carbon cycle balances volcanic outgassing, biological uptake, and rock burial to keep Earth habitable over geologic time.
Geology May Have Seeded Metabolism
- Life reduces CO2 into energetic organic matter using sunlight or geochemical gradients at vents.
- Alkaline hydrothermal vents likely provided natural electrochemistry that helped origin-of-life chemistry resemble modern metabolism.
Oxygen Built By Burial, Not Just Photosynthesis
- Earth's oxygenation occurred in stages and stayed low for a long time despite photosynthesis existing early on.
- Oxygen only accumulated when organic carbon was buried in the crust, preventing its reoxidation.
