Since the start of the industrial revolution, the acidity of the ocean's surface water has:

Correct option is D

Since the industrial revolution, the acidity of the ocean’s surface water has increased by approximately 30%. This is a direct result of rising levels of atmospheric carbon dioxide (CO₂) due to human activities. When CO₂ dissolves in seawater, it forms carbonic acid, which lowers the ocean’s pH, a process known as ocean acidification. This increased acidity negatively affects marine life, particularly organisms that rely on calcium carbonate for their shells and skeletons, such as corals and shellfish.
Information Booster: 1. Oceans absorb about 30% of the CO₂ emitted by human activities.
2. The pH of surface seawater has dropped from approximately 8.2 to 8.1 since the industrial revolution, representing a 30% increase in acidity.
3. Ocean acidification reduces the availability of carbonate ions, which are crucial for shell-building marine organisms.
4. Coral reefs, a key marine ecosystem, are particularly vulnerable to acidification.
5. Acidification also affects marine food webs, fisheries, and biodiversity.
6. Ocean acidification is considered one of the most pressing issues related to climate change and its impacts on marine ecosystems.
7. CO₂ absorbed by the ocean reacts with water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions, increasing acidity.
8. The 30% increase in acidity does not mean the ocean is "acidic" in the traditional sense (the pH is still above 7), but even small changes can have significant ecological effects.
9. Calcium carbonate-dependent organisms, like corals and mollusks, are particularly vulnerable because acidification reduces the availability of the ions they need to build their shells and skeletons.