What gas contributes 0.03% to the composition of the atmosphere?

Carbon dioxide is indeed the gas that contributes approximately 0.03% to the composition of the atmosphere. This trace gas plays a significant role in the Earth's climate system and is essential for photosynthesis in plants. Even though it represents a small percentage of the atmosphere, carbon dioxide is vital for maintaining the greenhouse effect, which helps regulate Earth's temperature.

While nitrogen is the most abundant gas in the atmosphere, making up about 78%, and oxygen accounts for around 21%, both of these gases are present in much larger concentrations than carbon dioxide. Ozone, although crucial for protecting life on Earth by absorbing harmful ultraviolet radiation, is found in varying concentrations and is typically present in the stratosphere rather than in the overall atmospheric composition. Thus, carbon dioxide stands out as a key component of the atmosphere, especially given its environmental relevance despite its low concentration.