Which environmental issue is primarily associated with carbon dioxide?

• A. Climate Change / Global Warming
• B. Acid Rain
• C. Smog
• D. Ozone Depletion

Answer: (A)

Carbon dioxide acts as a greenhouse gas that traps heat in the atmosphere, boosting the greenhouse effect and warming the planet. Increasing CO2 from burning fossil fuels raises the amount of heat retained in the lower atmosphere and surface, which leads to climate change or global warming. This is the environmental issue most directly linked to CO2 levels.

Acid rain, for example, comes mainly from sulfur dioxide and nitrogen oxides forming acidic rain, not from CO2. Smog is caused by pollutants like nitrogen oxides and volatile organic compounds reacting in sunlight to form ground-level ozone. Ozone depletion involves chlorine- and bromine-containing compounds from CFCs that break down stratospheric ozone. While these are important air-quality issues, CO2 is not the primary driver of them.