Glossary - Environmental Science - page 326

hazardous waste Waste that is flammable, corrosive, toxic, or reactive.
herbivores Plant-eating organisms.
herbivory A species interaction in which plants are consumed by animals.
HIPPCO The acronym used by biologists to summarize the important causes of the premature extinction of
organisms. Initially the acronym was HIPPO, but it was recently changed to HIPPCO. H stands for habitat de-
struction and fragmentation, I stands for invasive species, P stands for population growth, P stands for pollu-
tion, C stands for climate change, and O stands for overharvesting.
host An organism being invaded by a parasite.
hot spots Locations where magma emerges from the Earth, usually at the inner part of a tectonic plate.
hybrid electric vehicles Vehicles with electric motors, which are supplemented as needed by small gasoline
engines.
hydrochlorofluorocarbons (HCFCs) A group of manmade compounds that contain hydrogen, chlorine, fluor-
ine and carbon and have the potential to react with stratospheric ozone. Because they have shorter atmospheric
lifetimes than chlorofluorocarbons, they tend to break down in the troposphere before delivering reactive
chlorine to the stratosphere.
hydroelectric power Power that is produced by dammed water that is allowed to flow over turbines in a con-
trolled fashion, turning the turbines to produce electricity.
hydrofluorocarbons (HFCs) A group of manmade compounds containing carbon, hydrogen, and fluorine.
HFCs contain no chlorine and do not directly affect stratospheric ozone. Viewed as an acceptable long-term al-
ternative to CFCs and HCFCs, HFCs may still contribute to global warming.
hydrogen fuel cells Cells that use hydrogen and oxygen in a chemical reaction to produce energy and water.
hypoxic Describes an aquatic environment lacking in oxygen.
ice age A geological period of long-term reduction in the Earth's surface and atmospheric temperature, result-
ing in the presence or expansion of ice sheets and glaciers.
ice core A sample of ice that is typically drilled and removed from an ice sheet, usually the polar ice caps of
Antarctica or Greenland. Layers of the ice core are analyzed for trapped gas and deposits, which give an accur-
ate representation of historical climate and can be used to develop a climate record over a long period of time.
ice sheet A mass of ice that covers an area greater than 50,000 square kilometers (20,000 square miles). Ice
sheets also may be referred to as continental glaciers and are now found only in Greenland and Antarctica.
ice-minus strawberries Genetically modified, frost-resistant strawberries.
igneous rock Rock formed from cooling magma or other volcanic action.
Industrial Revolution The period of urbanization starting in the 1700s during which sanitation and medical
care improved, and manufacturing started to supplant agriculture as the primary human livelihood.
industrial smog Formed when anthropogenic sulfur dioxide (SO 2 ) absorbs ultraviolet radiation in the atmo-
sphere.