| Term | Definition | | Ozone | Ozone, the triatomic form of oxygen (O3), is a gaseous atmospheric constituent. In the troposphere, it is created by photochemical reactions involving gases resulting both from natural sources and from human activities (photochemical smog). In high concentrations, tropospheric ozone can be harmful to a wide range of living organisms. Tropospheric ozone acts as a greenhouse gas. In the stratosphere, ozone is created by the interaction between solar ultraviolet radiation and molecular oxygen (O2). |
| Ozone Layer | The layer of ozone that begins approximately 15 km above Earth and thins to an almost negligible amount at about 50 km, shields the Earth from harmful ultraviolet radiation from the sun. |
| Pandemic | A pandemic cuts across international boundaries, as opposed to regional epidemics. This wide geographical reach is what makes pandemics lead to large-scale social disruption, economic loss, and general hardship. |
| Parameter | A factor we measure. A climate parameter can be the amount of rainfall, maximum or average temperature, length of drought periods, and so on. |
| Passive Immunity | Protection against disease through antibodies produced by another human being or animal. Passive immunity is effective, but protection is generally limited and diminishes over time (usually a few weeks or months). For example, maternal antibodies are passed to the infant prior to birth and protect the baby for the first 4-6 months of life. |
| Pathogen Derived Resistance | A technique used to protect plants from viruses or infection. The process introduces a plant to a mild strain of a virus to protect the plant from a more severe strain of that same or very closely related pathogen. Eventually, the plant may build resistance to the virus. This technique is similar in nature to a human vaccination, which aims to build an individual's immunity to a virus or pathogen. |
| Pathogens | Organisms (such as bacteria, viruses, parasites and fungi) that cause disease in human beings. |
| Percentile | Given a set of numbers, the value below which a given percentage of observations fall. For example, if we had the following set of numbers {4, 7, 3, 9, 3}, the 60th percentile would be 4, because 3/5 x 100% = 60% of the set are equal to or less than 4. |
| Petrostates | Nations whose economies depend on fossil fuels have long invested in campaigns to undermine climate science, obstruct international agreements, and frame environmental action as a threat to national sovereignty. Their influence extends into global energy markets, diplomacy, and media ecosystems, ensuring that scientific warnings about planetary risk are met with political inertia. |
| Phenology | The timing of natural events, such as flower blooms and animal migration, which is influenced by changes in climate. Phenology is the study of such important seasonal events. Phenological events are influenced by a combination of climate factors, including light, temperature, rainfall, and humidity. |
