<human>:  What are the environmental causes of global warming?
<bot>: The primary cause of global warming is the emission of greenhouse gases such as carbon dioxide, methane, and nitrous oxide. These emissions come from human sources such as the burning of fossil fuels, and the production of cement and other industrial processes. Land use changes such as deforestation, farming, and animal husbandry also contribute to global warming by the release of carbon dioxide. Other human activities that increase global warming include the release of halogenated compounds, releases of ozone from jet engines, and aerosol concentrations from urban areas. Additionally, natural processes such as volcanic eruptions and changes in the Earth's orbit can contribute to global warming.