How are human activities disturbing carbon dioxide (CO\(_2\)) levels and affecting marine life?

• A. By increasing CO\(_2\) emissions, leading to ocean acidification that harms organisms with calcium carbonate shells.
• B. By decreasing CO\(_2\) emissions, causing oceans to become more alkaline and supporting coral growth.
• C. By reducing nutrient runoff, which decreases algal blooms and benefits marine biodiversity.
• D. By increasing oxygen levels in the atmosphere, resulting in higher rates of photosynthesis in marine plants.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the role of carbon dioxide (CO\(_2\)) in the environment. CO\(_2\) is a greenhouse gas that is naturally present in the atmosphere and is also absorbed by oceans. Human activities, such as burning fossil fuels and deforestation, increase CO\(_2\) emissions, which can disrupt natural processes.
2. Step 2: Explore the concept of ocean acidification. When excess CO\(_2\) is absorbed by seawater, it reacts with water to form carbonic acid (H\(_2\)CO\(_3\)). This process lowers the pH of the ocean, making it more acidic. Acidification can harm marine organisms, especially those with calcium carbonate (CaCO\(_3\)) shells or skeletons, such as corals, mollusks, and certain plankton species.
3. Step 3: Examine the impact of ocean acidification on marine life. Acidic conditions dissolve calcium carbonate structures, making it difficult for organisms to build and maintain their shells or skeletons. This can lead to population declines and disrupt marine ecosystems.
4. Step 4: Consider alternative scenarios presented in the problem. For example, decreasing CO\(_2\) emissions would reduce ocean acidification, potentially benefiting marine life. However, the problem specifically highlights the negative effects of increased CO\(_2\) emissions on marine organisms.
5. Step 5: Evaluate the correct answer based on the information provided. The correct answer is: 'By increasing CO\(_2\) emissions, leading to ocean acidification that harms organisms with calcium carbonate shells.' This aligns with the scientific understanding of how human activities impact CO\(_2\) levels and marine ecosystems.