The gas responsible for the greenhouse effect is primarily carbon dioxide (CO2). While other gases such as methane (CH4) and nitrous oxide (N2O) also contribute significantly, carbon dioxide is the most abundant among the greenhouse gases produced by human activity, particularly through fossil fuel combustion, deforestation, and industrial processes. The greenhouse effect occurs when these gases trap heat in the Earth's atmosphere, leading to an increase in global temperatures. This phenomenon is crucial for maintaining life on our planet; however, excessive greenhouse gas concentrations can lead to climate change and environmental challenges.