Which gas is primarily responsible for trapping heat in the atmosphere?

Carbon dioxide is primarily responsible for trapping heat in the atmosphere due to its properties as a greenhouse gas. Greenhouse gases, including carbon dioxide, absorb and re-radiate infrared radiation emitted from the Earth's surface. This process helps to maintain the planet's temperature, creating what is often referred to as the greenhouse effect.

Human activities, such as burning fossil fuels and deforestation, have significantly increased the concentration of carbon dioxide in the atmosphere, amplifying its heat-trapping effects and contributing to climate change. In contrast, gases like oxygen and nitrogen make up the bulk of the atmosphere's composition but do not have the molecular structure necessary to effectively trap heat. Argon, while present in the atmosphere, is also inert and does not influence heating processes significantly. This makes carbon dioxide's role in regulating the Earth's temperature crucial for understanding climate dynamics.