What is the greenhouse effect and why is it a concern for the environment?

What is the greenhouse effect and why is it a concern for the environment?

• A. Greenhouse gases trap heat in the lower atmosphere, causing warming and climate change; human activities increase these gases.
• B. Greenhouse effect shields Earth from solar radiation; increases in gases cool the planet.
• C. Greenhouse effect relates to plant greenhouses only and has no environmental impact.
• D. Greenhouse gases leave Earth’s atmosphere directly; they have no warming effect.

Answer: (A)

Heat is trapped by greenhouse gases in the Earth's atmosphere, which warms the surface. These gases—like carbon dioxide, methane, nitrous oxide, and water vapor—absorb infrared heat that would otherwise escape back to space and radiate some of it back toward the surface. This keeps the lower atmosphere warmer than it would be otherwise, which is the greenhouse effect. The concern comes from human activities increasing the amount of these gases, especially CO2 from burning fossil fuels and methane from agriculture and waste. More of these gases means more heat is trapped, enhancing warming and driving climate changes such as more extreme weather, melting ice, and rising sea levels. Why the other ideas don’t fit: the greenhouse effect does not shield Earth from solar radiation or cool the planet; it’s not limited to plant greenhouses and it isn’t true that greenhouse gases simply leave the atmosphere with no warming impact.

Heat is trapped by greenhouse gases in the Earth's atmosphere, which warms the surface. These gases—like carbon dioxide, methane, nitrous oxide, and water vapor—absorb infrared heat that would otherwise escape back to space and radiate some of it back toward the surface. This keeps the lower atmosphere warmer than it would be otherwise, which is the greenhouse effect.

The concern comes from human activities increasing the amount of these gases, especially CO2 from burning fossil fuels and methane from agriculture and waste. More of these gases means more heat is trapped, enhancing warming and driving climate changes such as more extreme weather, melting ice, and rising sea levels.

Why the other ideas don’t fit: the greenhouse effect does not shield Earth from solar radiation or cool the planet; it’s not limited to plant greenhouses and it isn’t true that greenhouse gases simply leave the atmosphere with no warming impact.