Question

carbon dioxide is naturally present in the atmosphere as part of the earths carbon cycle. human activities are altering the carbon cycle, by adding more co₂ to the atmosphere and by influencing the ability of natural sinks, like forests, to remove co₂ from the atmosphere. while co₂ emissions come from a variety of natural sources, human - related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution. consider the graph above. notice the trend in atmospheric carbon dioxide as recorded at recording stations over antarctica. hypothesize how the schematic of the carbon cycle might change if urbanization and deforestation continues unchecked. a both the carbon dioxide sinks and the carbon dioxide outputs will increase so the numbers should reach equilibrium. b the photosynthesis carbon sink will decrease in gigatons; the carbon dioxide output due to combustion will increase. c all of the carbon dioxide sinks will decrease in gigaton amounts; the carbon dioxide output due to combustion will increase. d carbon dioxide outputs due to combustion of fossil fuels continues to increase; the rate of photosynthesis will also continue to increase to accommodate this.

Explanation:

1. Analyze urbanization and deforestation: Urbanization leads to more fossil fuel combustion (increasing CO₂ output). Deforestation reduces forests, which are carbon sinks (via photosynthesis, etc.), so photosynthesis (a sink) decreases.
2. Evaluate options:

• Option A: Sinks and outputs reaching equilibrium is incorrect. Urbanization/deforestation increase output and decrease sinks, not balance.
• Option B: Photosynthesis sink (from forests) decreases with deforestation, and combustion output (from urbanization) increases. This matches.
• Option C: "All sinks" decreasing is extreme. Some sinks (like ocean) may not decrease, so incorrect.
• Option D: Photosynthesis rate won't increase with deforestation (less trees), so incorrect.

Answer:

B. The photosynthesis carbon sink will decrease in gigatons; the carbon dioxide output due to combustion will increase.