What are greenhouse gases?

Greenhouse gases are defined as gases that trap heat in the atmosphere, which is the fundamental reason for their significance in discussions regarding climate change and global warming. When these gases, such as carbon dioxide, methane, nitrous oxide, and water vapor, are present in the atmosphere, they allow sunlight to enter but impede the escape of heat back into space. This heat-trapping effect is crucial for maintaining the Earth’s temperature, enabling a hospitable environment for life. However, an excess of these gases enhances this natural greenhouse effect, leading to rising global temperatures and climate-related issues.

The other options describe different phenomena or environmental issues. Gases that deplete the ozone layer, for example, primarily include substances like chlorofluorocarbons (CFCs), which are not classified as greenhouse gases despite their environmental impact. Improving air quality generally pertains to reducing pollutants rather than trapping heat, and gases that contribute to acid rain involve sulfur dioxide and nitrogen oxides, which are also different from greenhouse gases. Understanding the specific roles and classifications of these gases is vital for effective environmental management and policy-making.