The
populations displayed on the clock are not intended to imply that the population
of the world is known to the last person. Rather, the clock is our estimate of
the world population size and an indication of how fast it is growing.
According to the current estimates, the world population reached 6 billion on
May 16, 1999, at about 10:23 AM GMT (May 16, 1999 at 5:23 AM EDT). Because of
the uncertainties of the estimates, and the fact that we are constantly
updating our estimates, the estimate of when 6 billion was hit will
change. The United Nations, whose population estimates differ somewhat from our
figures, celebrated the "Day
of 6 Billion"
on
October 12, 1999. The Census Bureau's new projections indicate that the 7
billion marker will be reached in July of 2012.
The world population estimates
and projections used to produce these figures were developed by the International Programs Center based on analysis of
available data on population, fertility, mortality, and migration. The analysis
was performed separately for the countries or areas of the world with a
population of 5,000 or more. Population estimates and projections analyses are
based on census, survey, and administrative information. For most countries,
and especially less developed countries, adjustment of the data is necessary to
correct for errors, omissions, and inconsistencies in the data. Since the most
recent data for each country are often at least 2 years old (and for most
countries they are older), the population figures used for the clock are
projections from those estimates based on assumed trends in fertility,
mortality, and migration. As new data become available, all data are
reevaluated and past conclusions may change. For general information about how
these estimates and projections are made, see the "Population Estimates and Projections
Methodology". These estimates and projections are contained in the International Data Base.
The World midyear population and
vital event estimates result from an aggregation of the figures for the
individual countries and areas. The intermediate population estimates are based
on a linear interpolation between successive midyear population figures. World
vital events for different units of time are computed based on the number of
months, days, hours, minutes, or seconds in the given year.
Figures may not add to totals due
to rounding.
