Question

How does global warming affect photosynthesis

Answer 1

Global warming leads to higher temperatures which can cause plants to lose CO₂ faster and close their stomata to conserve water, impacting photosynthesis negatively. Drought conditions, increasing respiration rates, and less water for NADPH formation further compound these effects. Overall, climate change presents complex challenges to the photosynthesis process and ecosystem health.

Step-by-step explanation:

Global warming affects photosynthesis in multiple ways. With an average temperature increase of 3-5°C, as expected due to global warming, photosynthesis may be affected due to the balance of photosynthesis and respiration in plants. While initial growth enhancement is predicted due to plants acclimating to warmer temperatures, factors such as an increase in respiration rates, especially under conditions of drought and stress, may diminish this benefit.

Moreover, plants may lose CO₂ more rapidly as gases diffuse faster in higher temperatures. On hot, dry days, plants conserve water by closing their stomata, which also reduces CO₂ intake, potentially slowing the Calvin cycle and affecting the photosynthesis process negatively. Additionally, with less water available, the formation of NADPH, crucial for photosynthesis, may also be impeded.

The increased concentration of carbon dioxide due to the greenhouse effect and the reduction of forests, which plays a role in removing CO₂ from the atmosphere, also contribute to the complexity of the impact on photosynthesis in the face of global climate change. These changes in global climate carry mixed effects on plant growth and agriculture, influencing not only photosynthesis but also the overall health of ecosystems.

Answer 2

Climate change affects plants in many different ways. Increasing CO(2) concentration can increase photosynthetic rates. This is especially pronounced for C(3) plants, at high temperatures and under water-limited conditions. Increasing temperature also affects photosynthesis, but plants have a considerable ability to adapt to their growth conditions and can function even at extremely high temperatures, provided adequate water is available. Temperature optima differ between species and growth conditions, and are higher in elevated atmospheric CO(2). With increasing temperature, vapour pressure deficits of the air may increase, with a concomitant increase in the transpiration rate from plant canopies. However, if stomata close in response to increasing CO(2) concentration, or if there is a reduction in the diurnal temperature range, then transpiration rates may even decrease. Soil organic matter decomposition rates are likely to be stimulated by higher temperatures, so that nutrients can be more readily mineralised and made available to plants. This is likely to increase photosynthetic carbon gain in nutrient-limited systems. All the factors listed above interact strongly so that, for different combinations of increases in temperature and CO(2) concentration, and for systems in different climatic regions and primarily affected by water or nutrient limitations, photosynthesis must be expected to respond differently to the same climatic changes.