How did the increase in oxygen impact life on Earth?

The increase in oxygen significantly impacted life on Earth by enabling the evolution of complex, multicellular organisms.

The rise in atmospheric oxygen, known as the Great Oxygenation Event, occurred around 2.4 billion years ago. This was a pivotal moment in Earth's history, as it set the stage for the evolution of complex life. Prior to this event, Earth's atmosphere was largely devoid of oxygen, and life was dominated by simple, single-celled organisms known as prokaryotes. These organisms were anaerobic, meaning they did not require oxygen for survival.

However, the emergence of cyanobacteria, which could perform photosynthesis, changed everything. These organisms used sunlight to convert water and carbon dioxide into glucose, a process that released oxygen as a by-product. Over time, the oxygen produced by cyanobacteria began to accumulate in the atmosphere, leading to a significant increase in atmospheric oxygen levels.

This increase in oxygen had profound effects on life on Earth. Firstly, it led to the extinction of many anaerobic organisms, which could not survive in an oxygen-rich environment. However, it also paved the way for the evolution of aerobic organisms, which use oxygen to produce energy through a process known as cellular respiration. This process is much more efficient than the anaerobic methods of energy production used by earlier organisms, allowing aerobic organisms to grow larger and more complex.

The rise in oxygen also led to the formation of the ozone layer, which protects life on Earth from harmful ultraviolet radiation. Without this protective layer, life as we know it would not be possible.

In summary, the increase in oxygen was a key factor in the evolution of complex, multicellular life on Earth. It led to the extinction of many anaerobic organisms, but also enabled the emergence of aerobic organisms and the formation of the ozone layer.