Q. Which of the following statements best describes "carbon fertilization"?
Answer: Increased plant growth due to increased concentration of carbon dioxide in the atmosphere
Notes: The correct answer is [A] Increased plant growth due to increased concentration of carbon dioxide in the atmosphere. Carbon fertilization, also known as the "CO2 fertilization effect," describes the process where higher levels of atmospheric carbon dioxide enhance the rate of photosynthesis in plants.

• Mechanism (Statement A – Correct): Plants use CO2, water, and sunlight to produce sugars through photosynthesis. When CO2 concentrations rise, many plants (especially C3 plants like wheat and rice) can increase their rate of carbon fixation, leading to faster growth, increased biomass, and improved water-use efficiency.
• Greenhouse Effect (Statement B – Incorrect): While increased CO2 does lead to higher global temperatures, this phenomenon is specifically termed the "Greenhouse Effect" or "Global Warming," not carbon fertilization.
• Ocean Acidification (Statement C – Incorrect): When the ocean absorbs excess CO2, it reacts with seawater to form carbonic acid, lowering the pH. This process is known as "Ocean Acidification," which can harm marine calcifiers like corals.
• Climate Adaptation (Statement D – Incorrect): This describes a broad biological and socio-economic response to climate change, rather than a specific physiological response of plants to carbon enrichment.

Recent satellite data and studies indicate that carbon fertilization has contributed significantly to the "greening" of the Earth over the past few decades, though the effect can be limited by the availability of other nutrients like nitrogen and phosphorus