Plants started to grow on the earth, plants breath in carbon dioxide (which is why it decreased so much) and they breath out oxygen. That is why the percentage of oxygen has increased so much.
Greate Oxygenation Event, This dramatically caused a new ice age because of the increase effecting the atmosphere.
iron
The amount of oxygen in the atmosphere increased because the number of photosynthetic organisms, which release oxygen, on the earth dramatically increased. This lead to the Great Oxygenation Event, or the Oxygen Crisis, 2.4 billion years ago - when this free O2 entered the Earth's atmosphere.
The atmosphere, during the Precambrian became richer in oxygen caused by a bacteria called cyanobacteria.
green vegetation are plants and of course plants give out oxygen and take our carbondioxide
21%
Greate Oxygenation Event, This dramatically caused a new ice age because of the increase effecting the atmosphere.
Oxygen, produces it.
Auroras are caused by charged solar particles colliding with atoms of oxygen and nitrogen in the ionosphere, which is the highest level of the atmosphere.
In oceans, Oxygen gets dissolved in a very small proportion from the atmosphere. This process is very gradual. Oxygen also comes from the aquatic plants present in the water bodies.
don't smoke, excercise, espessially walking.
iron
The amount of oxygen in the atmosphere increased because the number of photosynthetic organisms, which release oxygen, on the earth dramatically increased. This lead to the Great Oxygenation Event, or the Oxygen Crisis, 2.4 billion years ago - when this free O2 entered the Earth's atmosphere.
the "invention" (or development) of chlorophil by plants
The atmosphere, during the Precambrian became richer in oxygen caused by a bacteria called cyanobacteria.
Oxygen is already 20.946% by volume, So an increase of 0.054% should not make any difference
green vegetation are plants and of course plants give out oxygen and take our carbondioxide