The observed seasonal changes in atmospheric carbon dioxide concentrations in the Northern Hemisphere can be largely attributed to the activity of photosynthesis during the growing season. In spring, as leaves emerge, they increase the surface area available for photosynthesis, leading to a higher uptake of carbon dioxide from the atmosphere. This results in a decrease in atmospheric CO2 levels, reaching their lowest point in October, just before the leaves fall. In contrast, during winter, when photosynthesis slows down significantly due to the absence of foliage, carbon dioxide levels rise again, as there are fewer plants to uptake CO2. Thus, the annual cycle of leaf growth and senescence directly influences atmospheric carbon dioxide levels through the processes of photosynthesis and respiration.
Climate scientists have observed seasonal changes in atmospheric carbon dioxide concentration. In the Northern Hemisphere, they have measured the highest levels of carbon dioxide in the month of May. They have also measured the lowest levels of atmospheric carbon dioxide in the month of October. Hypothesize how photosynthesis can affect these changes. Consider the process of photosynthesis and its inputs and outputs. Explain your answer in three to five sentences.
Things to keep in mind as you develop your hypothesis:
In the Northern Hemisphere, leaves appear on trees in the spring and fall from trees in the autumn.
Leaves are where photosynthesis occurs.
How does photosynthesis effect carbon dioxide?
1 answer