fossil fuels as used in the passage includes

  If present trends continue, the world would face major crises by end of the century: insufficient cheap convenient energy. For without such energy, industrial production will fall, agricultural output will drop, transport will be restricted and standard of living in developed countries will plummet. At present, almost all our energy comes from fossil fuels. The earth’s reserves of fossil fuels have been formed from organic matter subjected to enormous heat and pressure of millions of years. But such reserves are finite. Because power demand is increasing very rapidly, fossil fuels will be exhausted within a relatively short time. We can estimate the amount of recoverable fuel under the surface of the earth and we know the rate at which it is being extracted. Fairly simple calculation can therefore determine its remaining life. If present trends continue, gas and oil reserves will be exhausted by the middle of the 21st century-about 70 years from now. Similar estimates for coal and wood reserves suggest a projected supply of 250-300 years. Of course long before fossil fuels are exhausted, demand will greatly exceed supply.

  For too many years, the world has consumed fossil fuels with little thought for the future. In fact, world energy consumption increased almost 600% between 1900 and 1965 and it is projected to increase by another 450% between 1965 and the year 2000. Crude oil has been pumped out of the ground for about 100 years, but over half of it is been consumed in the past 18 years. Coal has been mined for over 800 years, but over a half of it has been extracted in the past 37 years. In sum, most of the world’s consumption of energy from fossil fuels throughout history has taken place within living memory.