Question

there are roughly 720 billion metric tons of carbon in the atmosphere. an even bigger carbon sink is found in the oceans, which contain about 40 trillion metric tons. human activities increase the amount of carbon stored in these reservoirs. the primary source of this increase is the combustion of fossil fuels, which generates about 6 billion metric tons of carbon per year. deforestation adds an additional 2 billion metric tons annually. whereas 25% of this flux ends up being absorbed by the oceans and another 25% is absorbed by plants, 50% stays in the atmosphere for the duration of its residence time. how much carbon will human activities add to the atmosphere over the course of five years? 40 billion metric tons 8 billion metric tons 20 billion metric tons 10 billion metric tons

Explanation:

Step1: Calculate annual carbon added to atmosphere

Total annual carbon from human activities: \(6 + 2=8\) billion metric tons.
Portion staying in atmosphere: \(8\times50\% = 8\times0.5 = 4\) billion metric tons per year.

Step2: Calculate carbon added over five years

Multiply annual amount by 5: \(4\times5 = 20\) billion metric tons.

Answer:

20 billion metric tons