Global climate change: trends and variations in earth"s climate, involving temperature, precipitation, and storm frequency and intensity. Global warming: an increase in earth"s average surface temperature. Sun supplies energy atmosphere, clouds, land, ice, and water absorb 70% of insolation, reflecting 30% Surface materials increase in temperature and emit infrared radiation (radiation with longer wavelengths than visible light) Greenhouse gases (ghgs)/radiatively active gases: water vapour, ozone (o3), carbon dioxide (co2), nitrious oxide (n2o), methane (ch4) and halocarbons absorb infrared radiation. Some is lost to space, some returns warming the troposphere/surface (greenhouse effect) Human activities (anthropogenic) increased concentrations of ghgs over 250-300 years. Global warming potential: the relative ability of one molecule of a given greenhouse gas to contribute to warming. Carbon dioxide is most abundant, most potent ghg. Carbon is sequestered in the lithosphere deposition, partial decay, and compression of organic matter. Burned fossil fuels faster than can be replenished, cleared/burned forests.