Green plants use carbon dioxide (CO2) in the process of photosynthesis. This gas is absorbed from the atmosphere through small openings in the leaves called stomata. During photosynthesis, plants convert carbon dioxide, along with water and sunlight, into glucose and oxygen. This process is vital for producing the energy necessary for plant growth and survival, while also contributing to oxygen levels in the atmosphere, which is essential for most life forms on Earth. Therefore, carbon dioxide is crucial for not only the sustenance of plants but also for the overall health of our environment.