Predicting the global environmental changes that will occur because of human-directed activities in the future and how these changes might affect human health is difficult at best. Looking forward is necessary, however, because doing so enables one to anticipate where future health problems might arise. Future energy demand in China and India provides an apt example. The magnitude of air pollutants and greenhouse gases emitted by these countries will depend largely on how energy demand is met, with attendant consequences for human and indeed for planetary health. To understand these three trends, one must first understand the context in which they are occurring.
Population growth is a fundamental force underlying all others.
On a positive note, recent estimates suggest that population growth rates are slowing faster than demographers had projected. The global economy is burgeoning. This growth is expected to continue well into the middle of the next century. Liberalization has also greatly increased the flow of private capital into developing countries. Yet, this generally positive picture is still colored by regional differences and growing disparities between rich and poor.