Timeline of Oxygen in the Atmosphere
|
| |
|
Major Events |
Air / Climate |
Life |
More |
| A |
 |
- oceans in the air
- no life yet |
- 80% H2O
- 10% CO2
- 5-7% H2S
- Very Hot (Lava) |
- no life yet |
- tumultuous lava flows steam off any water |
B |
 |
- early life
- oxygen can't accumulate yet |
Intermittant Oxidation
- Snowball Earth |
- microscopic life, including algae |
- except during Ice Ages, surface metals are oxidized and absorb all available oxygen |
| C |
 |
- multicellular life |
- O2 up
- CO2 up
- Warm and Humid |
- strange plants and animals different from modern life |
- surface metals fully oxidized, so oxygen can now accumulate in atmosphere |
| D |
 |
- plants spread on land |
- O2 stable
- CO2 stable
- Warm, Wet and Mild |
- Trilobites, Snails, Fish
- Moss and Early Plants on land |
- plants and animals reach equilibrium, plants oxygen output is consumed by animal life |
| E |
 |
- early trees and ferns |
- O2 up
- CO2 down
- Arid to Warm Temperate |
- Trees and Ferns
- Insects, Amphibians |
- plants colonize land, increase oxygen and deposit carbon |
| F |
 |
- plants evolve bark
- much oxygen produced |
- O2 up a lot
- CO2 down a lot
- Cool and Wet |
- Plants evolve bark (8 bark to 1 wood!), nothing can eat it yet
- Giant Insects + Amphibians |
- plants evolve lignin (lotsa bark), thus temporary plant supremacy, even more oxygen, more carbon deposit
- industrial age coal comes from here |
| G |
 |
- (pangea) single continent
- hostile climate |
- O2 drops a lot
- CO2 low
- (Pangea) Single Continent
- Cool,
Very Dry
- Seasonal Rain |
- Conifers
- Cockroaches, Reptiles |
- desert too dry for many plants, so oxygen drops, carbon gap (very little deposit) |
| H |
 |
- dinosaurs |
- O2 up
- CO2 up
- Warm and Humid |
- Cycads and Ferns
- Dinosaurs |
- warm humid climate favorable to plants, so oxygen rises again |
| I |
 |
- no polar ice caps
- hothouse climate lets plants produce more oxygen |
- O2 up
- CO2 down
- Max Oceans (2/3 as much land)
- Hot and Wet
- even at the poles |
- Grass and flowers evolve
- Dinosaurs
- early Birds and Mammals |
- no polar ice caps
- hothouse climate lets plants make more oxygen, deposit more carbon
- shelled plankton deposit chalk on ocean bottom, reducing CO2 |
| J |
 |
- birds and mammals
- a few ice ages |
- O2 down
- CO2 down
- Cooling
- some Ice Ages |
- Savannah
- Mammals and Birds |
- ice caps return, and several ice ages
- lower oceans
- grasses dominate
- fewer plants, so oxygen goes down |
| K |
 |
- humans
- terraforming |
- CO2 up
- methane up a lot
- most stable climate ever, suitable for agriculture |
- Humans! |
- Humans dig up and burn fossil fuels, depleting atmospheric oxygen and increasing CO2 |
