California Climate Change Glossary

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Letter H

Halocarbons. Chemicals consisting of carbon, sometimes hydrogen, and either chlorine, fluorine bromine or iodine. (EPA)

Halons. These man-made substances (also known as bromofluorocarbons) are chlorofluorocarbons that contain bromine. See also Chlorofluorocarbons and Related Compounds. (EPA)

Hydrocarbons. Substances containing only hydrogen and carbon. Fossil fuels are made up of hydrocarbons. Some hydrocarbon compounds are major air pollutants. (EPA)

Hydrofluorocarbons (HFCs). These chemicals (along with perfluorocarbons) were introduced as alternatives to ozone depleting substances in serving many industrial, commercial, and personal needs. HFCs are emitted as by-products of industrial processes and are also used in manufacturing. They do not significantly deplete the stratospheric ozone layer, but they are powerful greenhouse gases with global warming potentials ranging from 140 (HFC-152a) to 12,100 (HFC-23). (EPA)

Hydrosphere. The part of the Earth composed of water including clouds, oceans, seas, ice caps, glaciers, lakes, rivers, underground water supplies, and atmospheric water vapor. (EPA)