Carbon dioxide functions as a greenhouse gas by ________.
a. Interfering with water's ability to absorb heat.
b. Increasing the random molecular motions of oxygen.
c. Allowing radiation from the sun to reach Earth and absorbing the re-radiated heat.
d. Splitting into carbon and oxygen and increasing the rate of cellular respiration.

Verified step by step guidance

1. Step 1: Understand the role of greenhouse gases. Greenhouse gases, such as carbon dioxide (CO₂), trap heat in Earth's atmosphere by absorbing and re-emitting infrared radiation. This process is essential for maintaining Earth's temperature but can lead to global warming if excessive amounts of greenhouse gases are present.
2. Step 2: Analyze the options provided. Each option describes a potential mechanism for how carbon dioxide might function as a greenhouse gas. Carefully evaluate each one based on your understanding of greenhouse gas behavior.
3. Step 3: Eliminate incorrect options. For example, (a) 'interfering with water's ability to absorb heat' is incorrect because water vapor and carbon dioxide both contribute to the greenhouse effect but do not interfere with each other. Similarly, (b) 'increasing the random molecular motions of oxygen' is unrelated to the greenhouse effect, and (d) 'splitting into carbon and oxygen and increasing the rate of cellular respiration' is a chemical process that does not occur in the atmosphere under normal conditions.
4. Step 4: Focus on the correct mechanism. Carbon dioxide allows solar radiation to pass through the atmosphere and reach Earth's surface. However, it absorbs the infrared radiation (heat) that is re-radiated from Earth's surface, trapping heat in the atmosphere. This aligns with option (c).
5. Step 5: Conclude that the correct answer is (c) 'allowing radiation from the sun to reach Earth and absorbing the re-radiated heat,' as this describes the primary mechanism by which carbon dioxide functions as a greenhouse gas.

Key Concepts

Greenhouse Effect

The greenhouse effect is a natural process where certain gases in Earth's atmosphere trap heat, preventing it from escaping back into space. This process is essential for maintaining the planet's temperature, allowing it to support life. Greenhouse gases, such as carbon dioxide, absorb and re-radiate infrared radiation, contributing to this warming effect.

Role of Carbon Dioxide

Carbon dioxide (CO2) is a significant greenhouse gas that plays a crucial role in the greenhouse effect. It allows sunlight to enter the atmosphere but absorbs and re-emits infrared radiation, which warms the atmosphere. Increased levels of CO2 from human activities enhance this effect, leading to global warming and climate change.

Radiative Forcing

Radiative forcing refers to the change in energy balance in the Earth's atmosphere due to factors like greenhouse gas concentrations. Positive radiative forcing, caused by increased greenhouse gases, leads to warming, while negative forcing can lead to cooling. Understanding radiative forcing is essential for assessing the impact of human activities on climate change.