What is the residence time of carbon in the reservoir that leads to photosynthesis?

The residence time of carbon in the reservoir that leads to photosynthesis, primarily in the atmosphere and oceans, is typically around 4 to 5 years. This timeframe reflects the duration carbon dioxide remains in the atmosphere before being absorbed by plants during photosynthesis. In contrast, carbon in terrestrial ecosystems, such as forests and soils, can have much longer residence times, ranging from years to centuries. Overall, the dynamic cycling of carbon between various reservoirs plays a crucial role in regulating the Earth's climate and supporting life.