Levels of other greenhouse gases have also increased because of human activities. Higher concentrations of greenhouse gases in the earth's atmosphere will lead to increased trapping of infrared radiation. The lower atmosphere is likely to warm, changing weather and climate. The changes will add to the natural greenhouse effect, producing an enhanced greenhouse effect. Possible impacts of the enhanced greenhouse effect on global and regional climate have been of increasing concern to scientists, the community and policy makers in recent years.
Greenhouse gases differ in their contributions to global warming.
For example, molecule for molecule, nitrous oxide and methane are more potent greenhouse gases than carbon dioxide. Most of the increase in carbon dioxide comes from burning of fossil fuels such as oil, coal and natural gas, and from deforestation. By 1994, the concentration was approximately 358 ppm. Australian annual carbon dioxide production per person is about 14 tonnes. The average Australian car, for example, releases over 4 tonnes of carbon dioxide each year.