of the Caspian Sea shows that that region as well as western Europe was subject to great climatic vicissitudes in the first half of the fourteenth century. In 1306-1307 the Caspian Sea, after rising rapidly for several years, stood thirty-seven feet above the present level and it probably rose still higher during the succeeding decades. At least it remained at a high level, for Hamdulla, the Persian, tells us that in 1325 a place called Aboskun was under water.[36]
Still further east the inland lake of Lop Nor also rose at about this time. According to a Chinese account the Dragon Town on the shore of Lop Nor was destroyed by a flood. From Himley's translation it appears that the level of the lake rose so as to overwhelm the city completely. This would necessitate the expansion of the lake to a point eighty miles east of Lulan, and fully fifty from the present eastern end of the Kara Koshun marsh. The water would have to rise nearly, or quite, to a strand which is now clearly visible at a height of twelve feet above the modern lake or marsh.
In India the fourteenth century was characterized by what appears to have been the most disastrous drought in all history. Apparently the decrease in rainfall here was as striking as the increase in other parts of the world. No statistics are available but we are told that in the great famine which began in 1344 even the Mogul emperor was unable to obtain the necessaries of life for his household. No rain worth mentioning fell for years. In some places the famine lasted three or four years, and in some twelve, and entire cities were left without an inhabitant. In a later famine, 1769-1770, which occurred in Bengal shortly after the foundation of British rule in
India, but while the native officials were still in power, a third of the population, or ten out of thirty millions, perished. The famine in the first half of the fourteenth century seems to have been far worse. These Indian famines were apparently due to weak summer monsoons caused presumably by the failure of central Asia to warm up as much as usual. The heavier snowfall, and the greater cloudiness of the summer there, which probably accompanied increased storminess, may have been the reason.
The New World as well as the Old appears to have been in a state of climatic stress during the first half of the fourteenth century. According to Pettersson, Greenland furnishes an example of this. At first the inhabitants of that northland were fairly prosperous and were able to approach from Iceland without much hindrance from the ice. Today the North Atlantic Ocean northeast of Iceland is full of drift ice much of the time. The border of the ice varies from season to season, but in general it extends westward from Iceland not far from the Arctic circle and then follows the coast of Greenland southward to Cape Farewell at the southern tip and around to the western side for fifty miles or more. Except under exceptional circumstances a ship cannot approach the coast until well northward on the comparatively ice-free west coast. In the old Sagas, however, nothing is said of ice in this region. The route from Iceland to Greenland is carefully described. In the earliest times it went from Iceland a trifle north of west so as to approach the coast of Greenland after as short an ocean passage as possible. Then it went down the coast in a region where approach is now practically impossible because of the ice. At that time this coast was icy close to the shore, but there is no sign that navigation was rendered difficult as is now the
case. Today no navigator would think of keeping close inland. The old route also went north of the island on which Cape Farewell is located, although the narrow channel between the island and the mainland is now so blocked with ice that no modern vessel has ever penetrated it. By the thirteenth century, however, there appears to have been a change. In the Kungaspegel or Kings' Mirror, written at that time, navigators are warned not to make the east coast too soon on account of ice, but no new route is recommended in the neighborhood of Cape Farewell or elsewhere. Finally, however, at the end of the fourteenth century, nearly 150 years after the Kungaspegel, the old sailing route was abandoned, and ships from Iceland sailed directly southwest to avoid the ice. As Pettersson says:
... At the end of the thirteenth and the beginning of the fourteenth century the European civilization in Greenland was wiped out by an invasion of the aboriginal population. The colonists in the Vesterbygd were driven from their homes and probably migrated to America leaving behind their cattle in the fields. So they were found by Ivar Bardsson, steward to the Bishop of Gardar, in his official journey thither in 1342.
The Eskimo invasion must not be regarded as a common raid. It was the transmigration of a people, and like other big movements of this kind [was] impelled by altered conditions of nature, in this case the alterations of climate caused by [or which caused?] the advance of the ice. For their hunting and fishing the Eskimos require an at least partially open arctic sea. The seal, their principal prey, cannot live where the surface of the sea is entirely frozen over. The cause of the favorable conditions in the Viking-age was, according to my hypothesis, that the ice then melted at a higher latitude in the arctic seas.
The Eskimos then lived further north in Greenland and North America. When the climate deteriorated and the sea which gave them their living was closed by ice the Eskimos had to find a more suitable neighborhood. This they found in the land colonized by the Norsemen whom they attacked and finally annihilated.
Finally, far to the south in Yucatan the ancient Maya civilization made its last flickering effort at about this time. Not much is known of this but in earlier periods the history of the Mayas seems to have agreed quite closely with the fluctuations in climate.[37] Among the Mayas, as we have seen, relatively dry periods were the times of greatest progress.
Let us turn now to Fig. 3 once more and compare the climatic conditions of the fourteenth century with those of periods of increasing rainfall. Southern England, Ireland, and Scandinavia, where the crops were ruined by extensive rain and storms in summer, are places where storminess and rainfall now increase when sunspots are numerous. Central Europe and the coasts of the North Sea, where flood and drought alternated, are regions which now have relatively less rain when sunspots increase than when they diminish. However, as appears from the trees measured by Douglass, the winters become more continental and hence cooler, thus corresponding to the cold winters of the fourteenth century when people walked on the ice from Scandinavia to Denmark. When such high pressure prevails in the winter, the total rainfall is diminished, but nevertheless the storms are more severe than usual, especially in the spring. In southeastern Europe, the part of the area whence the Caspian derives its water, appears to have less rainfall during times of increasing sunspots than when sunspots are few, but in an equally large area to the south, where the mountains
are higher and the run-off of the rain is more rapid, the reverse is the case. This seems to mean that a slight diminution in the water poured in by the Volga would be more than compensated by the water derived from Persia and from the Oxus and Jaxartes rivers, which in the fourteenth century appear to have filled the Sea of Aral and overflowed in a large stream to the Caspian. Still farther east in central Asia, so far as the records go, most of the country receives more rain when sunspots are many than when they are few, which would agree with what happened when the Dragon Town was inundated. In India, on the contrary, there is a large area where the rainfall diminishes at times of many sunspots, thus agreeing with the terrible famine from which the Moguls suffered so severely. In the western hemisphere, Greenland, Arizona, and California are all parts of the area where the rain increases with many sunspots, while Yucatan seems to lie in an area of the opposite type. Thus all the evidence seems to show that at times of climatic stress, such as the fourteenth century, the conditions are essentially the same as those which now prevail at times of increasing sunspots.