One mystery in environmental science is the imbalance in the "carbon dioxide budget." Considering only human activities, scientists have estimated that 1.6 billion metric tons of \(\mathrm{CO}_{2}\) is added to the atmosphere every year because of deforestation (plants use \(\mathrm{CO}_{2},\) and fewer plants will leave more \(\mathrm{CO}_{2}\) in the atmosphere). Another 5.5 billion tons per year is put into the atmosphere because of burning fossil fuels. It is further estimated (again, considering only human activities) that the atmosphere actually takes up about 3.3 billion tons of this \(\mathrm{CO}_{2}\) per year, while the oceans take up 2 billion tons per year, leaving about 1.8 billion tons of \(\mathrm{CO}_{2}\) per year unaccounted for. Describe a mechanism by which \(\mathrm{CO}_{2}\) is removed from the atmosphere and ultimately ends up below the surface (Hint: What is the source of the fossil fuels?) [Sections \(18.1-18.3 ]\)

Step by step solution

01

Understand the given data

The data provided in the exercise states that human activities add: - 1.6 billion metric tons of CO2 is added to the atmosphere yearly because of deforestation - 5.5 billion metric tons of CO2 due to burning fossil fuels Additionally, the atmosphere takes up 3.3 billion metric tons of CO₂ per year, the ocean takes up about 2 billion metric tons per year, leaving 1.8 billion metric tons of CO₂ per year unaccounted for.

02

Identify the source of fossil fuels

Fossil fuels, such as coal, oil, and natural gas, are formed from the remains of ancient plants and animals that have been subjected to heat and pressure over millions of years. They are primarily composed of carbon and hydrogen, and when burned as a fuel, they release CO2 into the atmosphere.

03

Understand the carbon cycle

The carbon cycle is a natural process through which carbon atoms circulate between the Earth's surface, atmosphere, and oceans. It includes key processes such as photosynthesis, respiration, and decomposition, and plays a significant role in determining the levels of CO2 in the atmosphere.

04

Describe a mechanism by which CO2 is removed from the atmosphere

One mechanism by which CO2 is removed from the atmosphere is through photosynthesis. Plants take in CO₂ from the atmosphere and, using sunlight, convert it into glucose and oxygen. This glucose can then be used by the plants for growth and is transformed into more complex organic molecules, such as cellulose and lignin. As these plants die and are buried under layers of sediment, they can become part of the fossil fuel formation process over millions of years, ultimately ending up below the Earth's surface in the form of coal, oil, or natural gas.

05

Conclusion

The unaccounted-for CO₂ may be getting sequestered in various ways, one of which is being incorporated into the process of fossil fuel formation. Photosynthesis by plants and other photosynthetic organisms removes CO₂ from the atmosphere and converts it into organic compounds. These compounds, through a series of geological processes, can eventually become fossil fuels, storing the carbon beneath the Earth's surface. However, burning fossil fuels releases this stored carbon back into the atmosphere in the form of CO₂, contributing to the global carbon budget imbalance.

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