Useful Terms & Conceptsadaptation: the adjustment of living things to environmental conditions. Human adaptation to climate change includes altering the way we grow crops, build homes, consume energy, and manage natural resources.
carbon cycle: the constant movement of carbon through living things, rocks, the oceans, and the atmosphere
carbon dioxide (CO2): a colorless, odorless gas that is naturally present in the atmosphere
climate: the average long-term weather (commonly years) in a particular region
climate models: computer programs that enable scientists to investigate the many factors at work in Earth's climate system. By manipulating variables such as the amount of CO2 in the atmosphere, scientists try to understand how the climate will respond.
fossil fuels: coal, oil, and natural gas, which formed from the remains of organisms that lived millions of years ago
global warming: an increase in the average temperature at Earth's surface caused by the buildup of greenhouse gases in the atmosphere
greenhouse effect: the process by which an atmosphere warms a planet. This takes place when gases allow sunshine to pass through the atmosphere but absorb the heat that radiates back from the surface, keeping it warm.
greenhouse gases: gases that increase global temperatures by absorbing the radiation emitted by Earth's surface. Carbon dioxide is the most important greenhouse gas as far as climate change is concerned. Other greenhouse gases include water vapor, methane, and nitrous oxide.
methane (CH4): a colorless, odorless, flammable gas produced by a variety of natural sources, including microorganisms, cattle, and termites
nitrous oxide (N2O): a colorless gas or liquid produced by the combustion of fossil fuel
paleoclimate: the past climate, before humans started measuring and recording it
parts per million (ppm): units used to measure concentrations of trace gases. Values refer to the number of specified molecules contained in 1 million molecules of dry air.
permafrost: the permanently frozen layer of soil beneath the surface in cold regions
photosynthesis: the process by which green plants use sunlight to synthesize food from CO2 and water. Photosynthesis releases oxygen into the atmosphere.
respiration: the process within living cells that releases CO2 and water when organic compounds combine with oxygen and break down
water cycle: the cycling of water among oceans and lakes, land, living organisms, and the atmosphere
water vapor: the gaseous state of water
weather: the state of the atmosphere at a particular place and time