What is the greenhouse effect?

The greenhouse effect refers to the process by which certain gases in the Earth's atmosphere trap heat, preventing it from escaping into space. This natural phenomenon is crucial for maintaining the Earth's temperature and supporting life. Solar radiation from the sun reaches the Earth's surface, where it is absorbed and then re-radiated as infrared energy. Greenhouse gases, such as carbon dioxide, methane, and water vapor, absorb and re-emit this infrared radiation, effectively keeping the atmosphere warmer than it would be without these gases.

This effect is fundamental to understanding climate change, as human activities have significantly increased the concentrations of greenhouse gases, leading to an enhanced greenhouse effect and global warming. The other choices presented do not correctly describe the greenhouse effect; they address different environmental concepts, such as emission reduction, the water cycle, and issues related to ozone depletion, which are distinct from the heat-trapping process that characterizes the greenhouse effect.