The main cause of the increase in the amount of CO₂ in Earth’s atmosphere over the past 170 years is


A. increased worldwide primary production.
B. increased worldwide fertilizer production.
C. increased infrared radiation absorption by the atmosphere.
D. the burning of fossil fuels and deforestation.

Verified step by step guidance

1. Identify the main sources of carbon dioxide (CO2) emissions. These include natural processes and human activities.
2. Consider the impact of primary production (option A) on CO2 levels. Primary production involves photosynthesis, which generally consumes CO2, rather than increasing it.
3. Evaluate the role of fertilizer production (option B) in CO2 emissions. While the production of fertilizers involves emissions, compare its scale and direct impact on atmospheric CO2 levels to other sources.
4. Analyze the effect of increased infrared radiation absorption (option C). Understand that this is a result of higher CO2 levels, not a cause of CO2 increases.
5. Examine how the burning of fossil fuels and deforestation (option D) contribute to CO2 emissions. Burning fossil fuels releases stored carbon, and deforestation reduces the number of trees available to absorb CO2 through photosynthesis.

Key Concepts

Carbon Dioxide Emissions

Carbon dioxide (CO2) is a greenhouse gas that traps heat in the atmosphere. Its levels have significantly increased due to human activities, particularly the burning of fossil fuels like coal, oil, and natural gas, which release CO2 as a byproduct. Understanding the sources of CO2 emissions is crucial for addressing climate change and its impacts.

Deforestation

Deforestation refers to the large-scale removal of trees from forested areas, which reduces the number of trees available to absorb CO2 from the atmosphere. This process not only contributes to increased CO2 levels but also disrupts ecosystems and biodiversity. The loss of forests exacerbates climate change by diminishing a natural carbon sink.

Greenhouse Effect

The greenhouse effect is a natural process where certain gases in the Earth's atmosphere trap heat, keeping the planet warm enough to support life. However, human activities have intensified this effect by increasing the concentration of greenhouse gases, such as CO2, leading to global warming and climate change. Understanding this concept is essential for evaluating the impact of increased CO2 levels.