Chapter 1 reviewed Malthusian concepts of the impact of demographic change. In 1650 the world's population was approximately 500 million, the number having doubled approximately every 1500 years since 8000 BC. In the next two centuries the world's population doubled again reaching 1 billion in 1850. Medical advances and improvements in sanitation and medicine in the developed world, resulting in a dramatic decline in deaths from disease, particularly among children, then saw the population double again in only 80 years. Then, as scientific advances extended across Asia and Africa, the population doubled again in only 40 years until, in 1990, the Earth's population was estimated at 5.3 billion (or 10% of the entire human population ever to have lived on Earth). It reached 6 billion in October 1999 and it is anticipated to be 9 billion by 2030 (Figure 12.1). Of the predicted population increase in the early twenty-first century, 95% will occur in the Third World, where resources of much needed water and agricultural land are most
limited. Life expectancy will continue to rise, resulting in a 'greying' of the global population, with all the implications that this will have for our welfare and the quality of life. Larger populations will put increased pressure on agricultural and industrial resources both at the local and global level. For example, increased population growth requires increased power generation, which in turn will exploit the Earth's reserves of fossil fuels at an even faster rate. If we look at the world's two most populous countries, China and India, one can gauge the impact that they might have as a major driving force in the world's population growth rate. In 1991, India's population was 846.3 million. At that time the population of China and India together constituted over 40% of the global population. In 1992 the annual growth rates for China and India were 1.5 and 2% respectively so that by 1999 India's population had risen to 989 million and it is clear that within the next 30 years India's population will overtake China's.