Gorrell, J. R.

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CLIMATIC CHANGES.BY DR. J. R. GORRELL.IS our climate becoming milder, and are our winters less severe?If so, what is the cause? There exists a concensus of opinionamong close observers of meteorological conditions that there hasbeen a perceptible change during the last fifty years. We may—they say—be unable to discover any difference from winter to win-ter, but a comparison of our late winters with the winters of 10, 20,30, 40 and 50 years ago, appears to justify the belief that a gradualchange is occurring in our climate.There are those who believe that the artificial groves through-out Iowa and adjoining states, have contributed materially to raisingthe temperature during the winter months. It is no doubt true thatthe rigor of the winds has been lessened thereby, but as the absolutetemperature is unaffected even by blizzards, it appears improbablethat the groves have any effect on the climate. There are otherswho attribute our milder winters to thermal regions in space throughwhich our solar system as a whole is passing. The solar system con-sisting of the sun, the planets—Mercury, Venus, Earth, Mars,Jupiter, Saturn, Uranus, Neptune—their Satellites, the Asteroidsbetween the orbits of Mars and Jupiter, and all meteoric matter andcomets that belong to our system, is rushing through space with avelocity of 39,600 miles an hour, and the direction is so near astraight line that it will require many millions of years to completeone revolution. It is therefore not impossible that the regions inspace through which we have been passing during the last two, three,four or five decades, has had a higher temperature than that throughwhich we passed before, because we may have approached nearerto some other sun in the sidereal system to which our solar systembelongs. The grove theory is unsatisfactory, and the effect of ourmovement through space is naught else than speculation.The heat of the surface of the earth and the atmosphere isCLIMATIC CHANGES. 413derived almost wholly from the sun. If the earth is a molten masswithin, the heat from that source, in hot springs, geysers and vol-canoes—if any of these have any connection with the central heat,which is improbable—is so small that it need not be considered in adiscussion of climatic conditions and causes.Some substances are transparent to light and heat that areopaque to heat without light. For example, if a pane of glass isheld between the face and the sun, the heat passes through the glassand the face is burned. If the same pane is held between the faceand an intensely hot cannon ball that is not incandescent, the glassacts as a perfect screen and no heat whatever is felt because the glassis opaque to dark heat.John Tyndall was the first to call the attention of scientists tothe fact that carbonic acid—carbon dioxide CO2—was partiallyopaque to dark heat, and to suggest its potency in producing a milderclimate. The proportion of carbon dioxide now in the atmosphereis only about one-thirtieth per cent, but being opaque to dark heatit absorbs the heat of the earth that otherwise would be radiatedinto space, and thus acts as a blanket to keep the earth warm. Thegreater the amount of carbon dioxide in the atmosphere the thickerbecomes the blanket, and the more heat it absorbs. The other con-stituents of the atmosphere—oxygen and nitrogen—are transparentto dark heat, and would therefore permit the radiation of the heatof the earth into space, and the result would be a cold and lifelessplanet.Prior to the Carboniferous era all the carbon dioxide nowstored in the coal measures of the earth (w^hich consist of 200,000square miles in China and Japan ; 194,000 in the United States;35,000 in India; 27,000 in Russia; 9000 in Great Britain; 3600in Germany ; 1800 in France ; 1400 in Belgium, Spain and othercountries, making a total of 471,800 square miles) was free in theatmosphere, and in consequence thereof there existed a tropicalclimate extending to the poles, as is indicated by the presence ojilyof tropical plants in coal-measures. It is estimated that the amountof carbon dioxide in the atmosphere during that period was fromfifty to one hundred thousand times greater than the amount nowin the atmosphere, and as a result of the warm moist climate thereflourished during that geological era the most luxuriant growth ofvegetation the earth has ever known, and the succeeding glacialperiod was the logical sequence of the withdrawal of the carbondioxide from the atmosphere.Prof. Joseph LeConte, in his Elements of Geology, says (page414 THE OPEN COURT.617) : "On account of its heat-absorbing properties, the carbondioxide is vastly the most important element affecting the climate.It now only forms about one thousandth part of the atmosphere.With its thermal potency it will be seen that comparatively slightvariation in the amount would produce great climatic effects. Phys-icists have long recognized this fact. It is believed that doublingthe present small amount of carbon dioxide, would produce a mildclimate to the poles, and that halving the present amount wouldbring on another glacial period."The rapid increase in the consumption of coal, and the inevitableincrease in the amount of carbon dioxide thrust into the atmospherebecomes apparent from the following facts : The consumption of coalin the United States in the year 1845, was four and one-half milliontons ; in the year 1864, twenty-two million tons ; in the year 1874,fifty million tons ; in the year 1884, one hundred and six milliontons ; in 1894, one hundred and fifty million tons ; in 1899, two hun-dred and forty-three million tons. In Great Britain in the year 1845,there was consumed thirty-one million tons ; in the year 1864, ninetymillion tons ; in the year 1874, one hundred and twenty-five milliontons ; in 1884, one hundred and sixty million tons ; in 1894, onehundred and sixty-four million tons ; and in 1899, two hundred andninety-five million tons. And the rate of increase in other countries—China and Japan, India, Russia, Germany, France, Spain, Belgiumand Austria-Hungary—is approximately the same. There is atpresent a concurrence of opinion among the highest authorities thatthe world's supply of coal would probably last two or three cen-turies, but the rapidly increasing rate of consumption is becomingominous. "The statements of former years that the supply of coalwas inexhaustible were not only false and foolish, but pernicious."The processes of combustion and respiration consume oxygenand liberate carbon dioxide and aqueous vapor. The incalculablecombustion of coal and oil is gradually restoring to the atmospherethe hitherto confined carbon dioxide which when free produced amild climate the world over, and will probably again create thesame meteorological conditions of heat and moisture that existedduring the Tertiary period—a tropical climate from pole to pole.

Climatic Changes.

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Climatic Changes.

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