464 A TREATISE ON METAMORPHISM. 



increased in importance. But it is only during the last half of the 

 nineteenth century that the quantity of carbon compounds artificially 

 oxidized has become of importance. In the year 1899 the amount of coal 

 mined and oxidized amounted to 723,287,454 metric tons. At the begin- 

 ning- of the last decade of the nineteenth century, 1890, the production 

 was only 511,518,358 metric tons." This shows how rapid the increase 

 in the use of coal has been, and therefore a combustion of 1,000,000,000 

 metric tons a year is probably very conservative as the estimated average 

 for the present century. Taking 1,000,000,000 metric tons as the amount 

 of coal oxidized per annum for the future, and supposing the amount of 

 carbon in this coal to average 80 per cent, the quantity of C0 2 which 

 passes into the atmosphere would be 2,933,333,000 metric tons per annum. 

 This is 0.1233 per cent of the total amount of C0 2 at present in the 

 atmosphere. (See p. 972.) If this rate of consumption of coal were 

 continued eight hundred and twelve years the amount of C0 2 in the 

 atmosphere would be doubled. 



It therefore appears probable that within a comparatively short time 

 in the future, as compared with a single geological period, or even an 

 epoch, the amount of C0 2 in one of its great reservoirs, the atmosphere, will 

 be increased to an important extent. From this fact various geological 

 consequences are likely to follow. One of the most important of these is 

 a higher average of temperature for the globe." According to Arrhenius, "if 

 the carbon dioxide is increased 2.5 to 3 times its present value, the tem- 

 perature in the arctic regions must rise 8° to 9° C. and produce a climate 

 as mild as that of the Eocene period." According to the above com- 

 putation, the C0 2 would be increased by the oxidation of coal alone to three 

 times its present amount in one thousand six hundred and twenty-four 

 3-ears. Certain it is, if Arrhenius be correct, and the coal supplies of the 

 world are sufficient to meet the demands of man for thousands of years, that 

 a most profound change will take place in the climate of the world. 



"Parker, E. W., Mineral Resources of the United States, 1S99; Coal: Twenty-first Ann. Rept. 

 U. S. Geol. Survey, pt. 6, 1901, p. 369. 



!> Chamberlin, T. C, An attempt to frame a working hypothesis of the cause of -the Glacial 

 periods on an atmospheric basis : Jour. Geol., vol. 7, 1899, pp. 545-584. 



c Arrhenius, Svante, On the influence of carbonic acid in the air upon the temperature of the 

 ground: Philos. Mag., 5th ser., vol.41, 1896, pp. 237-276. Summary in Jour. Geol., vol. 7, pp. 

 623-625. 



