Carrying Capacity: the maximum population of a species that a particular habitat can sustain with being degraded

Climate: The long term average weather for an area: Months, years, centuries.

Ecological footprint: the amount of biologically productive land/sea area needed to support the lifestyle of humans

Exponential Growth: The rate of growth for a population if it has a constant birth rate over time and is never limited by other factors

Ecosystem: the physical factors (i.e. water, soil, air) and biological entities (plants, animals) that interact within a habitat

Geothermal energy: the utilization of high temperatures within the earth to heat water to either heat buildings or generate electricity

Linear Growth: “when something grows the same exact amount in each time frame” (Retrieved from:

Natural Capital: The natural resources and services that keep life on Earth alive and support our economy.

Natural resources: materials and energy found in nature that we use: examples include solar energy, coal, oil, soil, water, air, trees, fish, copper, aluminum, etc.

Nitrogen Fixation: As N2, Nitrogen is inert, and most organisms can’t use it to build proteins.  The N2 has to be converted into usable molecules by separating the two Nitrogen atoms and adding Hydrogen to them in varying amounts to create ammonia and other Nitrogen compounds. 
Biodiversity: variety of the species on the Earth

Nonrenewable resources: resources that are not replaced as fast as they are used. Examples: coal, oil, fish, copper, aluminum, etc.

Population Growth Rate: is the increase in a country’s population during a period of time, usually one year, expressed as a percentage of the population at the start of that period. (Retrieved from:

Population momentum: Reaching replacement level fertility rate does not immediately stop population growth, because the current children will grow up and also give birth to 2.1 children, putting off the stop in population growth by a generation.   This delay in leveling of the population is called population momentum.

Renewable resources: resources that are replaced at a rate equal to or greater than the rate at which they are used. Examples: solar, soil, water, air, trees

Sustainability: “meet the needs of the present without compromising the ability of future generations to meet their own needs” -from the United Nations General Assembly (1987) Report of the World Commission on Environment and Development: Our Common Future.

Total fertility rate: Average number of children born to women during their reproductive years.
Replacement level fertility rate:  The number of children a couple must give birth to replace themselves

Weather:  the state of atmospheric conditions over a short period of time:  Hours or days.