Question

Choose the best answer to each of the following. Explain your reasoning with one or more complete sentences. If Earth were to be moved to Venus's orbit, it would probably (a) stay about the same temperature, thanks to the small amount of \(\mathrm{CO}_{2}\) in Earth's atmosphere; (b) become a tropical paradise; (c) suffer a runaway greenhouse effect and become even hotter than Venus is today.

Short answer

(c): Suffer a runaway greenhouse effect and become even hotter than Venus.

Step-by-step solution

Analyze Earth's Atmosphere

First, understand that Earth's atmosphere contains a small amount of carbon dioxide (CO_2), which plays a crucial role in its greenhouse effect, maintaining temperatures conducive to life.

Examine Venus's Orbit and Conditions

Next, recognize that Venus is closer to the Sun than Earth, receiving significantly more solar energy. Furthermore, Venus already has an extreme greenhouse effect primarily due to its dense CO_2 atmosphere, resulting in very high surface temperatures.

Relate Conditions to Earth's Potential State

If Earth were moved to Venus's orbit, it would receive more solar energy. Despite having less CO_2, solar input could heighten Earth's greenhouse effect, leading to potential atmospheric changes.

Predict Likely Outcome for Earth

Given the increased solar exposure, Earth's relatively small amount of CO_2 could lead to a scenario that's less drastic than Venus's but enough to initiate a runaway greenhouse effect. Earth's temperature could rise significantly, potentially exceeding Venus's current temperatures due to intensified climate dynamics.

Choose and Justify the Best Answer

Option (c) is the best choice: Earth would likely suffer a runaway greenhouse effect and could become even hotter than Venus is today due to increased solar energy and possible atmospheric feedback mechanisms.

Key concepts

Venus

Venus is one of the most fascinating planets in our solar system due to its extreme conditions. It is often referred to as Earth's "sister planet" because of their similar sizes, masses, and compositions. However, the two planets are drastically different when it comes to surface environment.
Venus is much closer to the Sun compared to Earth, which makes it receive almost twice the solar energy. The planet is covered by a thick atmosphere, composed mainly of carbon dioxide (CO₂), with clouds of sulfuric acid, creating a massive greenhouse effect. This effect traps heat, raising the surface temperature of Venus to around 465°C (869°F), which is hotter than Mercury, even though Venus is not the closest planet to the Sun.
Understanding Venus's atmosphere and conditions is essential for studying what happens when planets experience extreme greenhouse effects.

Earth's Atmosphere

Earth's atmosphere is a delicate mixture of gases that sustain life. It primarily contains nitrogen (78%) and oxygen (21%), with trace amounts of carbon dioxide, water vapor, and other gases. The presence of carbon dioxide is vital for the greenhouse effect, which keeps our planet warm by trapping some of the Sun's energy.
This greenhouse effect is essential for maintaining Earth's temperature at a level where life can thrive. However, the balance of greenhouse gases must be carefully maintained. Too much CO₂ leads to excessive warming, while too little can result in a cold, inhospitable environment.
Comparing with Venus, where CO₂ is dominant in its atmosphere, Earth's CO₂ volume looks minuscule but is still crucial in the framework of climate dynamics. If its position relative to the Sun changed as imagined in the exercise, it could lead to significant environmental changes.

Solar Energy

Solar energy is the fundamental driver of climate and weather systems on Earth. It refers to the radiant light and heat generated by the sun. This energy is incredibly important for all living organisms, as it powers photosynthesis, influences climate patterns, and regulates temperatures.
Earth's distance from the Sun plays a big role in the kind and amount of solar energy it receives. Currently, this distance allows Earth to maintain temperatures that are generally stable and suitable for life. If Earth were to move closer to the Sun, like the position of Venus, it would receive much more solar energy.
This increase in solar input could enhance the greenhouse effect, possibly triggering changes in the atmosphere similar to what has happened on Venus, ultimately leading to a runaway climatic situation.

Climate Dynamics

Climate dynamics is the study of how various factors impact the climate system's behavior over time. It examines patterns, cycles, and feedback mechanisms which contribute to climate change and stability.
The concept of feedback is important here. Positive feedback amplifies change, such as when warming causes ice to melt, reducing reflectivity and causing further warming. Negative feedback works in the opposite way, dampening changes and maintaining stability.
On Earth, these dynamics are delicately balanced, but any significant shifts in solar energy input or atmospheric composition can destabilize this balance. Should Earth experience changes in its orbit, or should atmospheric conditions shift significantly, it might enter into a phase of drastic warming, known as a runaway greenhouse effect—as speculated in the exercise if Earth were moved to Venus's orbit.