Which human activity is most directly linked to increasing atmospheric CO2 concentrations?

Which human activity is most directly linked to increasing atmospheric CO2 concentrations?

• A. Deforestation.
• B. Industrial solvent use.
• C. Burning fossil fuels.
• D. Agricultural irrigation.

Answer: (C)

Burning fossil fuels is the most direct way human activity raises atmospheric CO2. When coal, oil, or natural gas are burned for energy, the carbon stored in those fuels combines with oxygen to form carbon dioxide, which enters the atmosphere. This releases a lot of CO2 quickly and adds to atmospheric concentrations because the carbon in fossil fuels has been locked away for millions of years and isn’t being recycled locally by plants at the same scale. Deforestation also increases CO2, but mainly by reducing the forest’s ability to remove CO2 from the air and by releasing stored carbon when trees are cleared or burned. It’s an important contributing factor, but its effect is more about reducing sinks and releasing stored carbon rather than the immediate, large-scale emission from combustion. Industrial solvent use can contribute some CO2, but it’s small compared to fossil-fuel combustion. Agricultural irrigation doesn’t add CO2 directly in a meaningful way.

Burning fossil fuels is the most direct way human activity raises atmospheric CO2. When coal, oil, or natural gas are burned for energy, the carbon stored in those fuels combines with oxygen to form carbon dioxide, which enters the atmosphere. This releases a lot of CO2 quickly and adds to atmospheric concentrations because the carbon in fossil fuels has been locked away for millions of years and isn’t being recycled locally by plants at the same scale.

Deforestation also increases CO2, but mainly by reducing the forest’s ability to remove CO2 from the air and by releasing stored carbon when trees are cleared or burned. It’s an important contributing factor, but its effect is more about reducing sinks and releasing stored carbon rather than the immediate, large-scale emission from combustion. Industrial solvent use can contribute some CO2, but it’s small compared to fossil-fuel combustion. Agricultural irrigation doesn’t add CO2 directly in a meaningful way.