California Climate Change Glossary

Letter T

Temporal Scale. Climate may vary on a large range of temporal scales. Temporal scales may be seasonal to even geological, which goes up to hundreds of millions of years. (Lenn)

Terrestrial Biosphere. A collective term for all living organisms on land. (IPCC)

Thermal Expansion. An decrease in water density of oceans that results from global warming. This leads to an expansion of the ocean volume and hence an increase in sea level. (Lenn)

Thermocline. The region of the world's ocean, typically at a depth of lkm, where temperature decreases rapidly with depth and which marks the boundary between the surface and Deep Ocean. (IPCC).

Thermohaline Circulation. Large-scale density-driven circulation I the oceans, driven by differences in temperature and salinity. (IPCC)

Tide Guage. Device at a coastal location or deep-sea location for continuous measurement of the sea level with respect to the adjacent land. (Lenn)

Trace Gas. Any one of the less common gases found in the Earth's atmosphere. Nitrogen, oxygen, and argon make up more than 99 percent of the Earth's atmosphere. Other gases, such as carbon dioxide, water vapor, methane, oxides of nitrogen, ozone, and ammonia, are considered trace gases. Although relatively unimportant in terms of their absolute volume, they have significant effects on the Earth's weather and climate. (EPA)

Transient Climate Response. The tirne-dependent response of the climate system or model to a tirne-varying change of forcing. (IPCC)

Tropopause. The boundary between the troposphere (q.v.) and the stratosphere (q.v.) (IPCC)

Troposphere. The lowest layer of the atmosphere. The troposphere extends from the Earth's surface up to about 10-15 km. See also Atmosphere.

Tropospheric Ozone (O3). Ozone that is located in the troposphere and plays a significant role in the greenhouse gas effect and urban smog. See Ozone for more details. (EPA)

Tropospheric Ozone Precursor. Gases that influence the rate at which ozone is created and destroyed in the atmosphere. Such gases include: carbon monoxide (CO), nitrogen oxides (NOx), and nonmethane volatile organic compounds (NMVOCs). (EPA)

Turn-over time. The ratio between the mass of a reservoir (e.g. mass of N₂0 in the atmosphere) and the rate of removal from the reservoir (e.g. for N₂0, the rate of destruction by sunlight in the stratosphere (q.v.). (IPCC)