Demography (from prefix demo- from Ancient Greek δῆμος dēmos meaning "the people", and -graphy from γράφω graphō, implies "writing, description or measurement") is the statistical study of populations, especially human beings. As a very general science, it can analyze any kind of dynamic living population, i.e., one that changes over time or space (see population dynamics). Demography encompasses the study of the size, structure, and distribution of these populations, and spatial or temporal changes in them in response to birth, migration, aging, and death. Based on the demographic research of the earth, earth's population up to the year 2050 and 2100 can be estimated by demographers. Demographics are quantifiable characteristics of a given population.
In biology, a population is all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding. The area that is used to define a sexual population is defined as the area where inter-breeding is potentially possible between any pair within the area, and where the probability of interbreeding is greater than the probability of cross-breeding with individuals from other areas.
The blunt truth about the politics of climate change is that no country will want to sacrifice its economy in order to meet this challenge.
Tony Blair, address to the 2005 G8 climate change summit in London, as reported by David Adam, "Blair signals shift over climate change", The Guardian, 1 November 2005.