In the United States, for example, consumption dropped from 91 million to 63 million metric tons between 1980 and 1994. In the former Soviet Union, iron consumption fell from 198 million to 169 million metric tons and iron reserves decreased from 93 billion to 65 billion metric tons of iron content. 63 Less developed countries' consumption of other metals and minerals is also growing rapidly, although per capita consumption of most resources remains much higher in the industrialized countries. Per capita consumption of copper, for example, was about 17 times greater in industrialized countries than in less developed countries in the late 1980s. In addition to emitting greenhouse gases, the burning of fossil fuels releases particulates that have been associated with increased cancer risk, respiratory disease, and other health problems.
Petroleum plays a central role in world energy supplies and markets.
Estimates of petroleum reserves rose about 43 percent between 1984 and 1994, mainly because of revised estimates of reserves in the Middle East, but petroleum reserves have been declining in the former Soviet Union and the United States. They provide about three-fourths of commercial energy production in China and India. The burning of coal produces more particulates and greenhouse gases than the other forms of fossil fuels. Air pollution from coal fires blanketed London in the 19th century and currently plagues many urban areas in China and India. Natural gas, the least environmentally damaging greenhouse gas, provides about 23 percent of global commercial energy.