Lesson 4: Life's Effect on Earth Atmosphere

Atmospheric Equilibrium and Consequences for Life

Atmospheric equilibrium, or the balance of gases in Earth's atmosphere, plays a crucial role in sustaining life on our planet. This balance is essential for maintaining stable temperatures and the right mix of gases for living organisms. For instance, oxygen is abundant due to the equilibrium between processes like photosynthesis and respiration. Additionally, the greenhouse effect, which relies on the equilibrium of gases like CO2 and water vapour, helps trap enough heat to keep Earth warm. However, disturbances to this equilibrium, such as increased greenhouse gas emissions from human activities, can lead to consequences like global warming and climate change. Understanding and preserving atmospheric equilibrium are crucial for ensuring a habitable environment for diverse forms of life on Earth.

The infographic below shows that Earth’s atmosphere is 78% N2 and 21% O2. The rest of the atmosphere is made of a mix of other gases, including CO2 which is a greenhouse gas that humans have a direct impact on as well as Ozone (O3) which acts as a radiation shield that is crucial for life to exist on Earth. The equilibrium of these compounds greatly influences how life functions on Earth and the specific equilibrium we have is unique to our planet.

Evidently, scientists can be more specific about the composition of our atmosphere in the modern day and can also model how it would have changed over time. Below is a comparison between Earth’s prebiotic atmosphere and our modern day atmosphere.

Presently, the big discussion revolved around how humans make an impact on CO2. The following clip is a visual aid to show how the concentration of this greenhouse gas changes in the span of a year.