Climate Change Glossary
Word Definitions Related to
Climate Change and Global Warming
Temporal scale
See spatial and termporal scales
Thermal
Ther·mal ['th&r-m&l]. Thermal properties are dependent on temperature; they are related to, or caused by, heat.
Thermal expansion
In connection with sea level, this refers to the increase in volume (and decrease in density) that results from warming water. A warming of the ocean leads to an expansion of the ocean volume and hence an increase in sea level.
Thermohaline Circulation
Large-scale density-driven circulation in the ocean, caused by differences in temperature and salinity. In the North Atlantic the thermohaline circulation consists of warm surface water flowing northward and cold deep water flowing southward, resulting in a net poleward transport of heat. The surface water sinks in highly restricted sinking regions located in high latitudes.
Threshold
Any level of a property of a natural socioeconomic system beyond which a defined or marked change occurs. Gradual climate change may force a system beyond such a threshold. (see critical threshold)
Tide gauge
A device at a coastal location (and some deep sea locations) which continuously measures the level of the sea with respect to the adjacent land. Time-averaging of the sea level so recorded gives the observed Relative Sea Level Secular Changes.
Topography
To·po·gra·phy [t&-'pä-gr&-fE]. The configuration of a surface including its relief and the position of its natural and man-made features. The shape of a surface.
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.
Transient climate response
The globally averaged surface air temperature increase, averaged over a 20 year period, centred at the time of CO2 doubling, i.e., at year 70 in a 1% per year compound CO2 increase experiment with a global coupled climate model.
Troposphere
The lowest part of the atmosphere from the surface to about 10 km in altitude in mid-latitudes (ranging from 9 km in high latitudes to 16 km in the tropics on average) where clouds and "weather" phenomena occur. In the troposphere temperatures generally decrease with height. See ozone precursors, stratosphere, atmosphere.
Tropospheric Ozone (O3)
See ozone.
Tropospheric Ozone Precursors
See ozone precursors.
Turnover time
See: Lifetime.
