the World POPClock and World Vital Events

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 July 15, 1999, at about 5:19 AM GMT (July 15 at 1:19 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 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 228 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 Appendix B of the report Global Population Profile: 2002. 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.
What can I say?The population of the world is becoming larger and larger .Everyone notices this problem now.We just hold the meeting to talk about it?No,we should deal with it.Different countries face different problems.There are main two kinds of population problems.Firstly,some developing countries face the high speed of population.They face high population with the low resources.Secondly, some developed countries face population become smaller and smaller. Their birth rates are too low.Even though some countries appear negative numbers. Such as Japan and Germany.We need balance the population of every country.