What term is used for the release of harmful gases such as CO2 into the atmosphere?

The term specifically associated with the release of harmful gases such as carbon dioxide (CO2) into the atmosphere is greenhouse gas emissions. This term captures the essence of gases that contribute to the greenhouse effect, where they trap heat in the Earth's atmosphere, leading to climate change and global warming. Essentially, greenhouse gases include CO2, methane, and nitrous oxide, among others, and their emissions are a significant factor in environmental concerns today.

While pollution is a broader category that includes various contaminants released into air, water, or soil, greenhouse gas emissions focus explicitly on gases that have warming effects. Ozone depletion relates to the degradation of the ozone layer due to substances like chlorofluorocarbons (CFCs) and does not directly equate to the emission of greenhouse gases. Waste refers to any unwanted materials, but it doesn't specifically denote the atmospheric release of gases. Thus, greenhouse gas emissions is the most precise term for the situation described in the question.