Past geological events show that CO₂ levels can drastically alter the planet; humans are now changing the atmosphere rapidly, with consequences we must address.
Pangaea (meaning "all lands").
: Earth’s mantle is kept in a molten state by heat left over from the planet's formation and the decay of radioactive elements . Human Evolution & Climate cosmos a spacetime odyssey episode 9 worksheet answer key
Need answer keys for other Cosmos episodes? Search for “Cosmos Episode [Number] Worksheet Answer Key” on this site, or check the companion archive. Past geological events show that CO₂ levels can