Photosynthesis: the Cornerstone of Life.
Let’s go back 2.7 billion years. The Earth is well
and truly uninhabitable. The atmosphere is full of carbon dioxide, methane,
ammoniac, a bit of nitrogen thank to volcanic eruptions, water vapour and no
oxygen. The sun is 20% weaker than today but with the greenhouse effect, it’s still a tad less than 40 degrees out there.
Cyanobacteria appear somewhere in the shallow ocean and kick start the Great
Oxidation Event, doing the fantastic job plants still do today: photosynthesis.
Cyanobacteria are
blue-green algae. They use visible light, water and carbon dioxide to make
carbohydrates and oxygen. The more efficient green algae appear only 2 billion
years later, followed by land plants another half billion years later.
Current plants like
trees and cabbages use bits of green stuff called chlorophyll that look very
much like the early cyanobacteria and produce exactly the same photosynthetic
reactions. The cornerstone of life, indeed. However, about 70% of the Earth
oxygen production (and carbon storage) still comes from the oceans. It is a
great idea to plant trees for thousands of reasons, but it is an even better
idea to stop polluting the oceans. It’s a matter of life or
death.
Comments
Post a Comment