Research in UCLA’s Department of Atmospheric and Oceanic Sciences has supported the overwhelming scientific consensus that the Earth’s climate is changing and that habitability is declining by many measures; that much of this climate change and habitat degradation is due to human activities such as land use change and the emission of absorbing aerosols and greenhouse gases; and that climate change produces a variety of mostly harmful impacts on society and the biosphere. For further information on these issues, see statements by the American Geophysical Union, the American Meteorological Society, and a joint statement by the National Academies of Sciences of 13 large countries