What are the effects of increased carbon dioxide levels in a diver?

Increased carbon dioxide levels in a diver primarily lead to headaches and impaired motor functions due to a condition known as hypercapnia, which is the buildup of carbon dioxide in the bloodstream. As carbon dioxide levels rise, it disrupts the body's acid-base balance, leading to a decrease in pH levels (acidosis). This physiological change can cause symptoms such as confusion, dizziness, and headaches. Moreover, high levels of carbon dioxide can directly affect the central nervous system and impair motor functions, increasing the risk of accidents while diving.

The other options do not accurately reflect the physiological effects of elevated carbon dioxide. Enhanced visibility is not a consequence of high CO2 levels; in fact, increased CO2 can impair cognitive function and awareness. Increased buoyancy is influenced by the diver's physique, gear, and aquatic environment, not CO2 levels, and improved breathing is counterintuitive since elevated CO2 typically leads to respiratory distress rather than improvement. Enhanced oxygen levels in the blood are also not linked to increased carbon dioxide; rather, they can occur with supplemental oxygen, but elevated CO2 can actually reduce the efficiency of oxygen utilization in the body.