The population of the Earth has kept on increasing non-stop. In 1650 it is calculated that the population of the planet was 500 million, while a century later, in1750, it grew to 700 million. In 1850 it had arrived at 1.170 million, and 1900 at 5.000 million. Continuing this geometric progression, in year 2000 the Earth was already filled by 7.000 millionpersons. That is, from 170 years that were needed to duplicate the population of the planet three centuries ago has been reduced today to only 30 years. Controversy exists among those who believe thatthe science will solve the problem of the incessant growth of the population and those who affirm that the population has already surpassed he resources available. Human population trends are centrallyimportant to environmental science because they help to determine the environmental impact of human activities. Rising populations put increasing demands on natural resources such as land, water, andenergy supplies. As human communities use more resources, they generate contaminants, such as air and water pollution and greenhouse gas emissions, along with increasing quantities of waste.Population Growth
Birth and death rates are the most important determinants of population growth; in some countries, net migration is also important in this regard. To calculate population growth rates,demographers take the difference between births and deaths in a given time period, add the net number of migrants (which for the world as a whole is 0), and divide that number by the total population.For example, there are now about 136 million births and 58 million deaths worldwide annually, adding a net of 78 million new inhabitants to a global population of 6.7 billion, a growth rate of nearly1.2 percent.
Humans live on average 39.5 years in Swaziland and 81 years in Japan.The oldest confirmed recorded age for any human is 122 years. This is referred to as the...