1. THE EARTH IS A LIVING PLANET – IT BREATHES
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Aug 7, 2017
Changes in the Composition of the Atmosphere

2. The Earth is the way it is because of the living things on it…

3. Earth History
4.5 million to present
(1/1000th of earth history)
bya: Oxygen
1.8 bya: first eukaryote
0.9 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
0.065 bya:Cenozoic
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

4. The Effects of Life over Earth’s History: 2.2 bya
How do we know that oxygen wasn’t always present in the Earth’s atmosphere? Maybe Earth is just different from Venus and Mars…
Banded iron formations are first seen 2.5 billion years ago, showing that oxygen must have been present in the ocean to precipitate iron out of solution as iron oxides in sedimentary strata. There absence in older strata means that oxygen was not present in appreciable amounts.

5. The Effects of Life over Earth’s History: 350 mya
Terrestrial plants were radiating, sucking up CO2 and producing O2.
Huge expanses of swamp forests dominated the equatorial zone. Photosynthetic rates were high, but the trees were preserved under sediments when they died and fell…. Creating our coal deposits. Photosynthesis produced lots of O2, but with less decay, it stayed in the air instead of being breathed in and used by decomposing bacteria.

6. The Effects of Life over Earth’s History: 350 mya
The Carboniferous “Pulse”

7. The Effects of Life over Earth’s History: 65 mya

8. The K-T Extinction affected atmospheric oxygen levels as plants went extinct and terrestrial photosynthetic activity declined.

9. Thousands of Genera Millions of Years Ago
All genera
“well described” genera
The “big five” Mass Extinction Events
Thousands of Genera
Millions of Years Ago

10. The Effects of Life over Earth’s History: now

11. BIODIVERSITY NOW

12. ?

13. Millenium Ecosystem Assessment (2006)

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15. Insect Diversity

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24. Herbivores, Predators, Detritivores, Pollinators
Herbivores, Predators, Detritivores, Pollinators

25. Most vertebrate species are fishes

26. But do we NEED all these species??

27. There’s a lot of redundancy in nature…

28. Are all species equally important? If not, which ones are critical?

29. with
without

30. What does biodiversity do??