In "Oxygen: the molecule that made the world"[1], Nick Lane also mentions the theory that these cyanobacteria are the reason we have liquid water on earth, whil

In "Oxygen: the molecule that made the world"[1], Nick Lane also mentions the theory that these cyanobacteria are the reason we have liquid water on earth, while mars (for example) doesn't. It goes like this: early earth was subjected to solar radiations which hit our liquid water, splitting H2O into separate oxygen and hydrogen elements. The very light hydrogen atoms (as ions, or maybe H2?) were escaping into space while the oxygen was trapped by oxydizing rocks. With the rise of cyanobacteria produced O2, the rocks became fully oxydized and O2 started to build up in the air: the split hydrogen would be more likely to recombine with atmospheric O2, keeping them on earth, and the ozone (O3) layer started to shield the water from these radiations in the first place, thus stopping the process and safeguarding our oceans. [1] https://www.amazon.com/dp/0198607830 https://www.amazon.com/dp/0198607830 (very cool read mixing early earth history, the rise of life, geology, biochemistry and phylogenetics + Dr Lane is an excellent writer. Published in 2002, he has many more good updated articles about it.)