The Greenhouse Effect — Reading Comprehension

Earth’s atmosphere acts like a protective blanket that helps control the planet’s temperature. Without it, the average surface temperature would be about -18°C, which is far too cold for most life forms to survive. The reason Earth stays much warmer—at an average of 15°C—is due to the greenhouse effect. This process is vital for maintaining conditions that support a wide range of organisms, from tiny bacteria to humans.

How the Greenhouse Effect Works

When sunlight reaches Earth, some of its energy is absorbed by the land and oceans, warming the planet’s surface. The surface then releases this energy back into the atmosphere as infrared radiation, which is a type of heat energy. However, not all the infrared radiation escapes into space. Certain gases in the atmosphere, called greenhouse gases, trap some of this heat. The main greenhouse gases are carbon dioxide (CO₂), water vapor, methane (CH₄), and nitrous oxide (N₂O). These gases allow sunlight to enter but absorb and re-emit infrared radiation, keeping the lower atmosphere warm. In fact, the greenhouse effect makes Earth about 33°C warmer than it would be without these gases.

Interactions and Examples

The greenhouse effect works as a system involving the Sun, the surface, and the atmosphere. For example, after a clear night following a cloudy day, temperatures often drop more because clouds, which contain water vapor, act as extra insulation. Another example is how deserts, with dry air and few clouds, can be very hot during the day but cold at night, because less heat is trapped. NASA and other research agencies use satellites and ground-based measurements to study the amounts of greenhouse gases and their effects on Earth’s heat balance. These scientific observations help us understand how small changes in gas concentrations can alter the entire system.

Human Impact and Global Change

Although the greenhouse effect is natural and necessary, human activities are changing its balance. Burning fossil fuels, cutting down forests, and raising large numbers of livestock increase the levels of greenhouse gases like CO₂ and methane. Since the late 1800s, the concentration of CO₂ in the atmosphere has risen by over 40%. This increase has led to more heat being trapped, causing the average global temperature to rise—a process known as global warming. The enhanced greenhouse effect has serious consequences, including melting ice caps, rising sea levels, and more extreme weather events.

Understanding the greenhouse effect is important for making decisions about energy use, conservation, and climate action. It connects to larger scientific ideas about Earth’s systems and how living things depend on stable environments. Scientists continue to research these interactions to help predict future changes and to inform public policy.

Interesting Fact: Venus, the second planet from the Sun, has a much stronger greenhouse effect than Earth. Its atmosphere is mostly carbon dioxide, making its surface hotter than a pizza oven—over 460°C!

What is the main function of Earth's atmosphere in relation to temperature?

Which process makes Earth about 33°C warmer than it would be otherwise?

Which of the following is NOT a greenhouse gas mentioned in the passage?

What is the role of greenhouse gases in the atmosphere?

In the passage, what does 'infrared radiation' mean?

What is an example of the greenhouse effect in daily life described in the passage?

How have human activities changed the greenhouse effect, according to the passage?

Which statement best explains why deserts can be very hot during the day but cold at night?

The greenhouse effect is necessary for life on Earth. (True/False)

Global warming is caused by a decrease in greenhouse gases. (True/False)