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Term Term description
Taiga forests

The coniferous or evergreen forest biomes of subarctic lands, covering vast areas of Russia, northern North America and Eurasia.


Philosophical, ethical, political and religious tradition of Chinese origin that emphasizes living in harmony with the Tao, meaning "way", "path" or "principle".


A term in Islam attributing Oneness to Allah and describing Him as being One and Unique, with no partner or peer in His Essence and Attributes.

tectonic plates

The Earth’s crust is composed of massive plates of irregularly shaped solid rock, both continental and oceanic lithosphere. Plate size can vary greatly, from a few hundred to thousands of kilometers across. These plates float on and travel independently over the mantle. Much of the Earth's seismic activity occurs at the boundaries of these plates.


The moral virtue of moderation.

Temperate region

Regions or horizontal bands of the earth that occur between 35 and 50 degrees N and S latitude, and have a climate intermediate between tropical and polar; moderate or mild in temperature.


A unit of power equal to one trillion watts (1012) watts, abbreviated as TW.


Of or living on land (as distinct from air or water).

terrestrial biomes

Any biome that occurs on land and is not aquatic. For example, the tropical rain forest, temperate deciduous forest, desert and grassland biomes are all terrestrial.

tertiary consumer

An organism that feeds on secondary consumers in a food chain.

The Pontifical Council for Justice and Peace

A dicastery (department) of the Roman Curia dedicated to "action-oriented studies' for the international promotion of justice, peace, and human rights from the perspective of the Roman Catholic Church.


In science, a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.

thermal expansion

The tendency of matter to increase in volume in response to an increase in temperature. For example, when water heats up, it expands. About half of the past century's rise in sea level is attributable to warmer oceans simply occupying more space.


The ability of some animals to maintain a constant internal body temperature independent of the external temperature.


Any of a class of organic chemical compounds containing an aromatic ring containing one sulfur atom, one nitrogen atom, and four carbon atoms. Thiazines are often used in making dyes, drugs, and insecticides.

Thwaites Glacier

Thwaites Glacier is West Antarctica's largest unstable glacier. Recent research has shown that global warming has accelerated calving of the Thwaites glacier. The new study by scientists at the University of Texas at Austin suggests that the glacier isn't just being eroded by warm oceans, but also by volcanic activity.


A saclike membrane in the chloroplasts of plant cells that is often arranged in stacks called grana and that is the site of the light reactions of photosynthesis.

time lapse photography

A technique whereby the frequency at which film frames are captured (the frame rate) is much slower than that used to view the sequence. When the frames are played at normal speed, time appears to be moving faster and thus lapsing. Processes that would normally appear subtle to the human eye, e.g. the melting of glaciers over a few decades become very pronounced when viewed over a period of minutes.


A metric ton.


The upper, outermost layer of soil, usually the top 2 inches (5.1 cm) to 8 inches (20 cm). It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.


In Judaism, the law of God as revealed to Moses and recorded in the first five books of the Ancient Hebrew scriptures.

trace nutrients

Essential food factors required in only small quantities by the body; for example, vitamins, trace minerals.

traditional ecological knowledge (TEK)

The evolving knowledge acquired by indigenous and local peoples over hundreds or thousands of years through direct contact with the environment. This knowledge is specific to a location and includes the relationships between plants, animals, natural phenomena, landscapes and timing of events that are used for lifeways, including but not limited to hunting, fishing, trapping, agriculture, and forestry. Also known as Indigenous Knowledge or Native Science.

traditional food systems
Traditional food systems involve farmers and fishers using mainly simple, unmechanized techniques with human or animal based power, little to no synthetic chemical applications or mechanized irrigation, and selling produce at local markets, unprocessed. Productivity is relatively low compared with modern systems, and production and trade are small-scale and localized. This type of agriculture is typically environmental and socially sustainable.
tragedy of the commons

A phrase used by ecologist Garret Hardin to denote a situation where individuals acting independently and rationally according their self-interest behave contrary to the best interests of the whole group by depleting some common resource.


Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. A specialized form of evaporation.


A method of fishing that involves pulling a fishing net through the water behind one or more boats.

Triple Bottom Line Accounting

A method of evaluating corporate performance by measuring the impact of the business operation on not only monetary profit, but also environmental sustainability and social responsibility.


Relating to the feeding habits of different organisms in a food chain or web.

trophic efficiency

The ratio of production at one trophic level to production at the next lower trophic level.

trophic levels

The position that an organism occupies in a food chain - what it eats, and what eats it. Each layer of this system relates to the one below it by absorbing a fraction of the energy it consumed.

trophic levels

The sequential positions in a food chain, occupied by primary producers at the bottom and in turn by primary, secondary, and tertiary consumers. Decomposers (detritivores) are sometimes considered to occupy their own trophic level.

trophic pyramid

The basic structure of interaction in all biological communities characterized by the manner in which food energy is passed from one trophic level to the next along the food chain. The base of the pyramid is composed of species called autotrophs, the primary producers of the ecosystem. All other organisms in the ecosystem are consumers called heterotrophs, which either directly or indirectly depend on the primary producers for food energy.

trophic structure

The pattern of movement of energy and matter through an ecosystem.

trophic transfer

Energy transfer (typically in the form of food calories) from one trophic level to the next within a  natural food web.


A regional band around the Earth's equator extending 23.5 degrees north and south of the equator, where the sun is directly overhead when it reaches its most northerly or southerly point in the sky. The tropics typically do not have warm and cold seasons, but rather are always warm and may experience wet and dry seasons.

tropospheric ozone

Ozone that is located closer to the ground or at ground levels where it can come into contact with people or objects. Tropospheric ozone should not be confused with ozone found in the stratosphere, which is the result of natural photochemical processes in the atmosphere.

Tu B'shvat

A ceremony within some sects of the Jewish religion, held on the 15th day of the Jewish month of Shevat and honoring the fruits of the earth.


Tundra is the coldest of all the biomes, occurring below the north pole and above the treeline in some large mountain ranges. A layer of permanently frozen subsoil called permafrost exists, consisting mostly of peat and gravel. The harsh living conditions and short growing season account for its low biodiversity. Warming in the tundra enhances decomposition of the peat under anoxic and water logged conditions, producing methane, a very potent greenhouse gas.

A violent tropical storm or cyclone occurring in the Western Pacific Ocean, Indian Ocean and China Sea.
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