Influences of Geographic Environment Part 70

[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.

Where warm ocean currents, like the Gulf Stream and Kuro Siwa, penetrate into temperate or sub-polar lat.i.tudes, or where cool ones, like the Peruvian and Benguela Currents wash the coasts of tropical regions, they enhance the power of the ocean and wind to mitigate the extremes of temperature on land. The warm currents, moreover, loading the air above them with vapor, provide a store of rain to the nearest wind-swept land. Hence both the rainfall and temperature of a given country depend largely upon its neighboring water and air currents, and its accessibility to the rain-bearing winds. If it occupies a marked central position in temperate lat.i.tudes, like eastern Russia or the Great Plains of our semi-arid West, it receives limited moisture and suffers the extreme temperatures of a typical continental climate. The same result follows if it holds a distinctly peripheral location, and yet lies in the rain-shadow of a mountain barrier, like western Peru, Patagonia and Sweden north of the sixtieth parallel. [See map page 484.]

[Sidenote: Effect of the westerlies.]

Owing to the prevalence of westerly winds in the Temperate Zones and particularly in the North Temperate Zone, the mean annual temperature is high on the western face of the northern continents, but drops rapidly toward the east.[1417] This is especially true of winter temperatures, which even near the eastern coast show the severity of a continental climate. Sitka and New York, Trondhjem and Peking have the same mean January temperatures, though Peking lies in about the lat.i.tude of Madrid, over twenty-three degrees farther south.

Europe's location in the path of the North Atlantic westerlies, swept by winds from a small and narrow ocean which has been super-heated by the powerful Gulf Stream, secures for that continent a more equable climate and milder winters than corresponding lat.i.tudes on the western coasts of North America, whose winds from the wide Pacific are not so warm.[1418]

Moreover, a coastal rampart of mountains from Alaska to Mexico restricts the beneficial influences of the Pacific climate to a narrow seaboard, excludes them from the vast interior, which by reason of cold or aridity or both must forever renounce great economic or historical significance, unless its mineral resources developed unsuspected importance. In Europe, the absence of mountain barriers across the course of these westerly winds from Norway to central Spain, and the un.o.bstructed avenue offered to them by the Mediterranean Sea during fall and winter, enable all the Atlantic's mitigating influences of warmth and moisture to penetrate inland, and temper the climate of Europe as far east as St.

Petersburg and Constantinople. Thus several factors have combined to give the western half of Europe an extraordinarily favorable climate.

They have therefore greatly broadened its zone of historical intensity toward the north, pushed it up to the sixtieth parallel, while the corresponding zone in eastern Asia finds its northern limit at the fortieth degree.

[Sidenote: Rainfall.]

Moisture and warmth are essential to all that life upon which human existence depends. Hence temperature and rainfall are together the most important natural a.s.sets of a country, because of their influence upon its productivity. The grazing capacity and wheat yield of southern Australia increase almost regularly with every added inch of rainfall.[1419] The map of population for the Empire of India clearly shows that a high degree of density accompanies a high and certain rainfall. Exceptions occur only where hilly or mountainous tracts offer scant arable areas, or where plains and valleys are spa.r.s.ely populated owing to political troubles or unhealthiness. Nearly three-tenths of the population are found crowded together on the one-tenth of India's level territory which is blessed with a rainfall above the average for the country.[1420] Deserts which yield nothing are purely climatic phenomena.

Steppes which facilitate the historical movement, and forests which block it, are products of scant or ample precipitation. The zonal distribution of rainfall, with its maxima in the Tropics and the Temperate Zones, and its minima in the trade-wind belts and polar regions, reinforces and emphasizes the influence of temperature in determining certain great cultural and economic zones.

In equatorial regions, which have an abundant rainfall throughout the year, agriculture is directed toward fruits and roots; only in certain districts can it include cereals, and then only rice and maize. The temperate grains demand some dry summer weeks for their maturity.

Excessive moisture in Ireland has practically excluded wheat-growing, which in England and Scotland also is restricted chiefly to the drier eastern counties.[1421] It thrives, on the other hand, in Manitoba and the Red River region even with a short season of scant rainfall, because this comes in the spring when moisture is most needed.[1422] Most important to man, therefore, is the question how and when the rainfall is distributed, and with what regularity it comes. Monsoon and trade-wind districts labor under the disadvantage of a wet and dry season, and a variability which brings tragic results, since it easily reduces a barely adequate rainfall to disastrous drought. These are the lands where wind and weather lord it over man. If the rains hold off too long, or stop too soon, or withhold even a small portion of their accustomed gift, famine stalks abroad.

[Sidenote: Temperature and zonal location.]

Temperature, the other important element of climate, depends primarily upon zonal location, which has far different historical results from central and peripheral location, continental and insular. It determines the amount of heat received from the sun, though air and ocean currents may redistribute that heat within certain limits, and humidity or aridity modify its effects. Still zonal distinctions remain. The great climatic regions of the earth, like the hot, wet equatorial belt or the warm, dry trade-wind belts or the cool, well-watered temperate zones, const.i.tute, through the medium of their economic products and their climatically imposed methods of production, so many socio-political areas, regardless of ethnic and political boundaries. The Berber nomads of the northern Sahara live much as the Semitic Bedouins of the Syrian desert or the Turkoman stock of arid Turkestan. They have the same tribal government, the same scattered distribution in small groups, the same economic basis of subsistence, though of different races and dominated respectively by France, Turkey and Russia. The history of the tropical Antilles has in both its economic and political features paralleled that of the East Indies since the early 16th century.

Temperate South America promises to follow in the historical footsteps of temperate North America, South Africa in those of Europe and temperate Australia.

[Sidenote: Reactions of contrasted zones.]

While people of the same lat.i.tude live approximately under the same temperature conditions, those of contrasted zones are subjected to markedly different influences. They develop different degrees of civilization, wealth, economic efficiency, and density of population; hence they give rise to great historical movements in the form of migration, conquest, colonization, and commerce, which, like convection currents, seek to equalize the differences and reach an equilibrium.

Nature has fixed the mutual destiny of tropical and temperate zones, for instance, as complementary trade regions. The hot belt produces numerous things that can never grow in colder countries, while a much shorter list of products, coupled, however, with greater industrial efficiency, is restricted to the Temperate Zone. This explains the enormous importance of the East Indian trade for Europe in ancient and medieval times, the value of tropical possessions for commercial countries like England and Holland. It throws light upon the persistence of the tropical plantation system in the Dutch East Indies and republican Mexico, as formerly in the sugar and cotton fields of the Southern States, with its relentless grip upon the throat of national life in hot lands.

[Sidenote: Temperate products from tropical highlands.]

Tropical regions, however, may profit by the fact that their mountains and plateaus permit the cultivation of temperate crops. India during the last century has introduced tea culture extensively on the a.s.sam and Nilgiri Hills, and in the Himalayan valleys up to an alt.i.tude of 7000 feet.[1423] Besides this temperate product, it has put large areas into cotton, chiefly in the peninsular plateau of the Deccan, and by means of these two crops has caused a considerable readjustment in world commerce.[1424] Nevertheless, here the infringement of the principle of tropical production in the torrid zone is after all slight. In tropical America, on the other hand, the case is quite different; this region presents an interesting paradox in relation to its foreign commerce.

Here the highlands are the chief seats of population. They contain, moreover, the most industrious and intelligent native stock, due to geographical and historical causes running back into the ancient civilizations, as well as the largest proportions of immigrant Europeans. This is true not only of the Cordilleran states from northern Mexico to the borders of Chile, but also of Brazil, whose center of population falls on the plateau behind Rio de Janeiro and Santos. The isolation of these high plateaus excludes them to a serious extent from foreign trade, while their great alt.i.tude permits only temperate products, with the exception of sub-tropical coffee, which is their only crop meeting a great demand. The world wants, on the other hand, the long list of lowland tropical exports which torrid America furnishes as yet in inadequate amounts, owing to the lack of an industrious and abundant lowland population. Commerce will eventually experience a readjustment in these localities to the natural basis of tropical production; but how soon or how effectively this change will take place depends upon the question of immigration of foreign tropical peoples, or the more difficult problem of white acclimatization.[1425]

[Sidenote: Isothermal lines in anthropo-geography.]

Despite some purely climatological objections, anthropo-geography finds the division of climatic zones according to certain isothermal lines of mean annual temperature the most expedient one for its purpose. The hot zone may be taken as the belt north and south of the equator enclosed between the annual isotherms of 20 C. (68 F.) These hold a course generally far outside the two tropics, and in the northern continents frequently reach the thirty-fifth parallel. The temperate climatic zones extend from the annual isotherm of 20 C. to that of 0 C. (32 F.), which bears little relation to the polar circles forming the limits of the solar Temperate Zone. The north temperate climatic zone has been further sub-divided along the annual isotherm of 5 C. (41 F.), distinguis.h.i.+ng thus the warmer southern belt, which forms preeminently the zone of greatest historical intensity. The areas beyond the annual isotherms of 0C. belong to the barren cold zones. [See map page 612.]

[Sidenote: Historical effect of compressed isotherms.]

This isothermal division of the climatic zones is abundantly justified, because the duration of a given degree of heat or cold in any region is a dominant factor in its human, animal, and plant life. A map of the mean annual isotherms of the earth is therefore eloquent of the relation between historical development and this one phase of climate. Where the lines run far apart, they enclose extensive areas of similar temperature; and where they approach, they group together regions of contrasted temperatures. The compression of climatic differences into a small area enlivens and accentuates the process of historical development. It produces the same sort of effect as the proximity of contrasted reliefs. Nowhere else in the world do the tropical and frigid climatic areas, as defined on the north and south by the annual isothermal lines of 20C. and 0C. respectively, lie so near together as in Labrador and northern Florida. Separated here by only twenty degrees of lat.i.tude, on the opposite side of the Atlantic they diverge so sharply as to include the whole western face of Europe, from Hammerfest and the North Cape down to the Canary Islands and the crest of the Atlas Mountains in Africa, a stretch of forty-two degrees of lat.i.tude. This approximation of contrasted climatic districts in North America was an immense force in stimulating the early economic development of the Thirteen Colonies, and in maturing them to the point of political autonomy. It gave New England commerce command of a nearby tropical trade in the West Indies, of sub-tropical products in the southern colonies, in close proximity to all the contrasted products of a cold climate--dense northern forests for naval stores and lumber, and an inexhaustible supply of fish from polar currents, which met a strong demand in Europe and the Antilles. The sudden southward drop of the 0C.

annual isothermal line toward the St. Lawrence and the Great Lakes brought the northwestern fur trade to the back gate of New York, where it opened on the Mohawk and upper Hudson, and brought prosperity to the young colony. Even to-day the center of collection for the Canadian fur fields is Quebec, located at 47 north lat.i.tude, while the corresponding point of concentration in Europe for the furs of Russia and Siberia is Nizhni-Novgorod, which lies ten degrees farther north.[1426]

[Sidenote: Effect of slight climatic differences.]