Global Warming Glossary *
Habitat - The locality or natural home in which a particular plant, animal, or group of closely associated organisms lives.
Hadley Circulation - A direct, thermally driven overturning cell in the atmosphere consisting of poleward flow in the upper troposphere, subsiding air into the subtropical anticyclones, return flow as part of the trade winds near the surface, and with rising air near the equator in the so-called Inter-Tropical Convergence Zone.
Halocarbons - A collective term for the group of partially halogenated organic species, including the chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), halons, methyl chloride, methyl bromide, etc. Many of the halocarbons have large Global Warming Potentials. The chlorine and bromine-containing halocarbons are also involved in the depletion of the ozone layer.
Hantavirus - A virus in the family Bunyaviridae that causes a type of haemorrhagic fever. It is thought that humans catch the disease mainly from infected rodents, either through direct contact with the animals or by inhaling or ingesting dust that contains aerosolized viral particles from their dried urine and other secretions.
Heat island - An urban area characterized by ambient temperatures higher than those of the surrounding non-urban area. The cause is a higher absorption of solar energy by materials of the urban fabric such as asphalt.
Herbaceous - Flowering, non-woody.
Heterotrophic respiration - The conversion of organic matter to carbon dioxide by organisms other than plants.
Holocene - The Holocene geological epoch is the latter of two Quaternary epochs, extending from about 11.6 ka to and including the present.
Hybrid vehicle - Any vehicle that employs two sources of propulsion, especially a vehicle that combines an internal combustion engine with an electric motor.
Hydrofluorocarbons (HFCs) - One of the six groups of gases to be curbed under the Kyoto Protocol. They are produced commercially as a substitute for chlorofluorocarbons. HFCs are largely used in refrigeration and semiconductor manufacturing. Their Global Warming Potentials range from 1,300 to 11,700.
Hydrographic events - Events that alter the state or current of waters in oceans, rivers or lakes.
Hydrological systems - The systems involved in movement, distribution, and quality of water throughout the Earth, including both the hydrologic cycle and water resources.
Hydrosphere - The component of the climate system comprising liquid surface and subterranean water, such as oceans, seas, rivers, fresh water lakes, underground water (groundwater), etc.
Hypolimnetic - Referring to the part of a lake below the thermocline made up of water that is stagnant and of essentially uniform temperature except during the period of overturn.
Hypoxic events - Events that lead to a deficiency of oxygen.
Glossaries of the contributions of Working Groups I, II and III to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report 2007.
Nakićenović, N., J. Alcamo, G. Davis, B. de Vries, J. Fenhann, S. Gaffin, K. Gregory, A. Grübler, T.Y. Jung, T. Kram, E.L. La Rovere, L. Michaelis, S. Mori, T. Morita, W. Pepper, H. Pitcher, L. Price, K. Raihi, A. Roehrl, H.-H. Rogner, A. Sankovski, M. Schlesinger, P. Shukla, S. Smith, R. Swart, S. van Rooijen, N. Victor and Z. Dadi, 2000: Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, and New York, 599 pp.