This page is part of the Earth Journalism Toolkit’s glossary.

Ocean acidification: reduction in pH of ocean water that is caused by its uptake of carbon dioxide from the atmosphere.

Old growth forest: an area of forest that has attained great age and is dominated by mature trees with little evidence of any disturbance such as logging.

Omnivore: an animal species that eats both plants and animals as its primary food source.

Open-pit mining (opencast mining, open-cut mining): a method of extracting rock or minerals from the earth by their removal from an open pit.

Organ: a fully differentiated structural and functional unit in an animal that is specialized for some particular function.

Organic agriculture: a farming system that avoids the use of synthetic fertilisers, pesticides and genetically modified organisms, minimises pollution of air, soil and water, and optimises the health and productivity of interdependent communities of plants, animals and people.

Organic: derived from a living organism.

Organochlorines: organic synthetic derivative of chlorine and mainly used as an insecticide or fungicide.

Pandemic: an epidemic over a wide geographical area

Pathogen: any disease-producing agent (especially a virus or bacterium or other microorganism)

Persistence: The quality of remaining for a long period of time (such as in the environment or the body). Persistent chemicals (such as DDT and PCBs) are not easily broken down.

Pest: Any unwanted and destructive insect or other animal that attacks food,  crops, livestock, buildings, etc.

Pesticide: Any substance or mixture of substance intended for preventing, destroying, repelling or mitigating any pest.

pH: A measure of the acidity or alkalinity of a solution, (where 7 is neutral and greater than 7 is more alkaline and less than 7 is more acidic).

Photovoltaic: refers to solar power technology that directly converts light into electricity

Plankton: mostly microscopic animal and plant life (phytoplankton) that lives in water and is a valuable food source for animals.

Polluter Pays Principle: the principle that producers of pollution should in some way compensate others for the effects of their pollution.

Polyethylene terephthalate (PET): a clear, tough, light and shatterproof type of plastic, used to make products such as soft drink bottles, film packaging and fabrics.

Polypropylene (PP): a member of the polyelofin family of plastics. PP is light, rigid and glossy and is used to make products such as washing machine agitators, clear film packaging, carpet fibres and housewares.

Polystyrene (PS): a member of the styrene family of plastics. PS is easy to mould and is used to make refrigerator and washing machine components. It can be foamed to make single use packaging, such as cups, meat and produce trays.

Polyvinyl chloride (PVC): a member of the vinyl family of plastics. PVC can be clear, flexible or rigid and is used to make products such as fruit juice bottles, credit cards, pipes and hoses.

Postconsumer waste: material or product that has served its intended purpose and has been discarded for disposal or recovery.

Potable: safe to drink

Precautionary Principle: where there are threats of serious irreversible environmental damage, lack of full scientific certainty should not be used as a reason for introducing measures to prevent that degradation (Rio Declaration).

Precipitation: (weather) any liquid or solid water particles that fall from the atmosphere to the Earth’s surface; includes drizzle, rain, snow, snow pellets, ice crystals, ice pellets and hail.
Pre-industrial: this generally means before 1750.

Prior Informed Consent: an ethical requirement that people have sufficient information about something (such as an experiment, drug treatment or a business deal) to enable them to make an informed judgment about whether or not to participate.