Part 70 (1/2)
[1406] George Adam Smith, Historical Geography of the Holy Land, pp.
259-261. New York, 1897.
[1407] Isabella Bird Bishop, Korea and Her Neighbors, pp. 21, 134-135, 140, 142. New York, 1897.
[1408] Article Waldenses, Encyclopaedia Britannica.
CHAPTER XVII
THE INFLUENCE OF CLIMATE
[Sidenote: Importance of climatic influences.]
Climate enters fundamentally into all consideration of geographic influences, either by implication or explicitly. It is a factor in most physiological and psychological effects of environment. It underlies the whole significance of zonal location, continental and insular. Large territorial areas are favorable to improved variation in men and animals partly because they comprise a diversity of natural conditions, of which a wide range of climates forms one. This is also one advantage of a varied relief, especially in the Tropics, where all the zones may be compressed into a small area on the slopes of high mountains like the Andes and Kilimanjaro. Climate fixes the boundaries of human habitation in Arctic lat.i.tudes and high alt.i.tudes by drawing the dead-line to all organic life. It dominates life in steppes and torrid deserts as in sub-polar wastes. It encourages intimacy with the sea in tropical Malays and Polynesians, and like a slave-driver, scourges on the fur-clad Eskimo to reap the harvest of the deep. It is always present in that intricate balance of geographic factors which produces a given historical result, throwing its weight now into one side of the scales, now into the other. It underlies the production, distribution and exchange of commodities derived from the vegetable and animal kingdoms, influences methods of agriculture, and the efficiency of human labor in various industries.[1409] Hence it is a potent factor in the beginning and in the evolution of civilization, so far as this goes hand in hand with economic development.
[Sidenote: Climate in the interplay of geographic factors.]
The foregoing chapters have therefore been indirectly concerned with climate to no small degree, but they have endeavored to treat the subject a.n.a.lytically, showing climate as working with or against or in some combination with other geographic factors. This course was necessary, because climatic influences are so conspicuous and so important that by the older geographers like Montesquieu[1410] and others, they have been erected into a blanket theory, and made to explain a wide range of social and historical phenomena which were properly the effect of other geographic factors.
[Sidenote: Direct and indirect effects of climate.]
For a clear understanding of climatic influences, it is necessary to adhere to the chief characteristics of the atmosphere, such as heat and cold, moisture and aridity, and to consider the effect of zonal location, winds and relief in the production and distribution of these; also to distinguish between direct and indirect results of climate, temporary and permanent, physiological and psychological ones, because the confusion of these various effects breeds far-fetched conclusions.
The direct modification of man by climate is partly an _a priori_ a.s.sumption, because the incontestable evidences of such modification are not very numerous, however strong the probability may be. The effect of climate upon plant and animal life is obvious, and immediately raises the a.s.sumption that man has been similarly influenced. But there is this difference: in contrast to the helpless dependence upon environment of stationary plants and animals, whose range of movement is strictly determined by conditions of food and temperature, the great mobility of man, combined with his inventiveness, enables him to flee or seek almost any climatic condition, and to emanc.i.p.ate himself from the full tyranny of climatic control by subst.i.tuting an indirect economic effect for a direct physical effect.
The direct results of climate are various, though some are open to the charge of imperfect proof. Even the relation of nigrescence to tropical heat, which seems to be established by the geographical distribution of negroid races in the Old World, fails to find support from the facts of pigmentation among the American Indians from Alaska to Tierra del Fuego.
Nevertheless climate undoubtedly modifies many physiological processes in individuals and peoples,[1411] affects their immunity from certain cla.s.ses of diseases and their susceptibility to others, influences their temperament, their energy, their capacity for sustained or for merely intermittent effort, and therefore helps determine their efficiency as economic and political agents.
While producing these direct effects, climate also influences man indirectly by controlling the wide range of his life conditions dependent upon the plant and animal life about him. It dictates what crops he may raise, and has it in its power to affect radically the size of his harvest. It decides which flocks and herds are best suited to his environment, and therefore directs his pastoral activities, whether he keeps reindeer, camels, llamas, horses or horned cattle. By interdicting both agriculture and stock-raising, as in Greenland whose ice cap leaves little surface free even for reindeer moss, it condemns the inhabitants forever to the uncertain subsistence of the hunter. Where it encourages the growth of large forests which harbor abundant game and yield abundant fruits, as in the hot, moist equatorial belt and on rainy mountain slopes, it prolongs the hunter stage of development, r.e.t.a.r.ds the advance to agriculture. Climate thus helps to influence the rate and the limit of cultural development. It determines in part the local supply of raw material with which man has to work, and hence the majority of his secondary activities, except where these are expended on mineral resources. It decides the character of his food, clothing, and dwelling, and ultimately of his civilization.
[Sidenote: Effect of climate upon relief.]
The very ground under man's feet, moreover, feels the molding hand of climate. In one region a former age of excessive cold has glaciated the surface and scoured off the fertile loam down to the underlying rock, or left the land coated with barren glacial drift or more productive clays.
In another, the cold still persists and caps the land with ice and snow, or, as in the tundra, underlays it with a stratum of frozen earth, which keeps the surface wet and chilled even in the height of summer. In yet other regions, abundant moisture combined with heat covers the ground with a pad of fertile humus, while some hundred miles away drying trade winds parch and crack the steppe vegetation, convert most of its organic substance into gases, and leave only a small residue to enrich the soil.
Rain itself modifies the relief of the land, and therefore often decides in a slow, cosmic way what shall be the ultimate destination of its precious store of water. A heavy precipitation on the windward side of a mountain range, by increasing the mechanical force of its drainage streams, makes them bite their way back into the heart of the system and decapitate the rivers on the leeward side, thus diminis.h.i.+ng the volume of water left to irrigate the rainless slope. Thus the hydra-headed Amazon has been spreading and multiplying its sources among the Andean valleys, to the detriment of agriculture on the dry Pacific slope; thus the torrents of the Western Ghats, gorged by the monsoon rains from the Indian Ocean, are slowly nipping off the streams of the ill-watered Deccan, [See map page 484.] All these direct and indirect effects of climate may combine to produce ultimate politico-geographical results which manifest themselves in the expansion, power and permanence of states.
[Sidenote: Climate limits the habitable area.]
Climatic conditions limit the habitable area of the earth. This is their most important anthropo-geographic effect. At either pole lurks an invincible foe, with whom expanding humanity must always reckon, and who brooks little encroachment upon his territory. His weapon is the restriction of organic life, without which man cannot exist. The geographical boundaries of organic life, however, are wider than those of human life. The consequence of this climatic control, therefore, is not only a narrowed distribution of the human race, but a concentration which intensifies the struggle for existence, forces the utilization of all the available area, and thereby in every locality stimulates adaptation to environment.
[Sidenote: Adaptability of man to climatic extremes.]
Man ranks among the most adaptable organic beings on the earth. No climate is absolutely intolerable to him. Only the absence of food supply or of all marketable commodities will exclude him from the most inhospitable region. His dwellings are found from sea level up to an alt.i.tude of 5000 meters or more, where the air pressure is little over one half that on the coast.[1412] Seventeen per cent. of the towns and cities of Bolivia are located at an elevation above 13,000 feet (4000 meters), while Aullagas occupies a site 15,700 feet or nearly 5000 meters above the sea.[1413] Mineral wealth explains these high Bolivian settlements, just as it draws the Mexican sulphur miners to temporary residence in the crater of Popocatepetl at an alt.i.tude of 17,787 feet (5420 meters), from their permanent dwellings a thousand meters below.[1414] The laborers employed in the construction of the Oroya railroad in Peru became rapidly accustomed to work in the rarefied air at an elevation of 4000 to 4800 meters. The trade routes over the Andes and Himalayan ranges often cross pa.s.ses at similar alt.i.tudes; the Karakorum road mounts to 18,548 feet (5,650 meters). Yet these great elevations do not prevent men going their way and doing the day's work, although the unacclimated tenderfoot is liable to attacks of mountain sickness in consequence of the rarefied air.[1415]
Man makes himself at home in any zone. The cold pole of the earth, so far as recorded temperatures show, is the town of Verkhoyansk in northeastern Siberia, whose mean January temperature is 54 F. below zero (-48 Centigrade). Ma.s.sawa, one of the hottest spots in the furnace of Africa is the capital of the Italian colony of Eritrea. However, extremes both of heat and cold reduce the density of population, the scale and efficiency of economic enterprises. The greatest events of universal history and especially the greatest historical developments belong to the North Temperate Zone. The decisive voyages of discovery emanated thence, though the needs of trade and the steady winds of low lat.i.tudes combined to carry them to the Tropics. The coldest lands of the earth are either uninhabited, like Spitzenbergen, or spa.r.s.ely populated, like northern Siberia. The hottest regions, also, are far from being so densely populated as many temperate countries.[1416] [See maps pages 8, 9, and 612.] The fact that they are for the most part dependencies or former colonial possessions of European powers indicates their r.e.t.a.r.ded economic and political development. The contrast between the Mongol Tunguse, who lead the life of hunters and herders in Arctic Siberia, and the related Manchus, who conquered and rule the temperate lands of China, shows how climates help differentiate various branches of the same ethnic stock; and this contrast only parallels that between the Eskimo and Aztec offshoots of the American Indians, the Norwegian and Italian divisions of the white race.
[Ill.u.s.tration: MEAN ANNUAL ISOTHERMS AND HEAT BELTS [_Centigrade_]
0C = 32F. 20C = 68F. 30C = 86F.]
[Sidenote: Temperature as modified by oceans and winds.]
The zonal location of a country indicates roughly the degree of heat which it receives from the sun. It would do this accurately if variations of relief, prevailing winds and proximity of the oceans did not enter as disturbing factors. Since water heats and cools more slowly than the land, the ocean is a great reservoir of warmth in winter and of cold in summer, and exercises therefore an equalizing effect upon the temperature of the adjacent continents, far as these effects can be carried by the wind. The ocean is also the great source of moisture, and this, too, it distributes over the land through the agency of the wind.