Earth's Primordial Atmosphere
Initially, Earth's atmosphere was hydrogen-rich, stemming from solar nebula remnants. However, it was soon replaced by volcanic outgassing, releasing water vapor, carbon dioxide, nitrogen, but virtually no oxygen.
Second Atmosphere Emergence
Approximately 4 billion years ago, Earth's second atmosphere formed. Dominated by water vapor, carbon dioxide, and ammonia, it was the result of intense volcanic activity, which shaped atmospheric composition.
Water Vapor's Critical Role
As the planet cooled, water vapor condensed into the first rain, which filled basins to form oceans. These bodies of water became crucial in atmospheric and life evolution.
Around 2.4 billion years ago, cyanobacteria evolved photosynthesis, releasing oxygen and eventually leading to the Great Oxidation Event, which transformed the atmosphere and allowed for complex life to develop.
Atmosphere's Layered Structure
Earth's atmosphere is layered, including the troposphere where we live, and the stratosphere, which houses the ozone layer protecting us from harmful ultraviolet radiation.
Human Impact on Atmosphere
Since the Industrial Revolution, human activities have significantly altered the atmosphere's composition, contributing to climate change and ozone layer depletion with long-term global impacts.
Atmospheric Protection Efforts
International agreements like the Montreal Protocol have successfully curbed substances harmful to the ozone layer, demonstrating global cooperation can mitigate human impact on the atmosphere.