The Climatic Stress Of The Fourteenth Century
In order to give concreteness to our picture of the climatic pulsations
of historic times let us take a specific period and see how its changes
of climate were distributed over the globe and how they are related to
the little changes which now take place in the sunspot cycle. We will
take the fourteenth century of the Christian era, especially the first
half. This period is chosen because it is the last and hence the best
/>
known of the times when the climate of the earth seems to have taken a
considerable swing toward the conditions which now prevail when the sun
is most active, and which, if intensified, would apparently lead to
glaciation. It has already been discussed in World Power and
Evolution, but its importance and the fact that new evidence is
constantly coming to light warrant a fuller discussion.
To begin with Europe; according to the careful account of Pettersson[31]
the fourteenth century shows
a record of extreme climatic variations. In the cold winters the
rivers Rhine, Danube, Thames, and Po were frozen for weeks and
months. On these cold winters there followed violent floods, so that
the rivers mentioned inundated their valleys. Such floods are
recorded in 55 summers in the 14th century. There is, of course,
nothing astonishing in the fact that the inundations of the great
rivers of Europe were more devastating 600 to 700 years ago than in
our days, when the flow of the rivers has been regulated by canals,
locks, etc.; but still the inundations in the 13th and 14th
centuries must have surpassed everything of that kind which has
occurred since then. In 1342 the waters of the Rhine rose so high
that they inundated the city of Mayence and the Cathedral "usque ad
cingulum hominis." The walls of Cologne were flooded so that they
could be passed by boats in July. This occurred also in 1374 in the
midst of the month of February, which is of course an unusual season
for disasters of the kind. Again in other years the drought was so
intense that the same rivers, the Danube, Rhine, and others, nearly
dried up, and the Rhine could be forded at Cologne. This happened at
least twice in the same century. There is one exceptional summer of
such evil record that centuries afterwards it was spoken of as "the
old hot summer of 1357."
Pettersson goes on to speak of two oceanic phenomena on which the old
chronicles lay greater stress than on all others:
The first [is] the great storm-floods on the coast of the North Sea
and the Baltic, which occurred so frequently that not less than
nineteen floods of a destructiveness unparalleled in later times are
recorded from the 14th century. The coastline of the North Sea was
completely altered by these floods. Thus on January 16, 1300, half
of the island Heligoland and many other islands were engulfed by the
sea. The same fate overtook the island of Borkum, torn into several
islands by the storm-flood of January 16, which remoulded the
Frisian Islands into their present shape, when also Wendingstadt, on
the island of Sylt, and Thiryu parishes were engulfed. This flood is
known under the name of "the great man-drowning." The coasts of the
Baltic also were exposed to storm-floods of unparalleled violence.
On November 1, 1304, the island of Ruden was torn asunder from Rugen
by the force of the waves. Time does not allow me to dwell upon
individual disasters of this kind, but it will be well to note that
of the nineteen great floods on record eighteen occurred in the cold
season between the autumnal and vernal equinoxes.
The second remarkable phenomenon mentioned by the chronicles is the
freezing of the entire Baltic, which occurred many times during the
cold winters of these centuries. On such occasions it was possible
to travel with carriages over the ice from Sweden to Bornholm and
from Denmark to the German coast (Lubeck), and in some cases even
from Gotland to the coast of Estland.
Norlind[32] says that "the only authentic accounts" of the complete
freezing of the Baltic in the neighborhood of the Kattegat are in the
years 1296, 1306, 1323, and 1408. Of these 1296 is "much the most
uncertain," while 1323 was the coldest year ever recorded, as appears
from the fact that horses and sleighs crossed regularly from Sweden to
Germany on the ice.
Not only central Europe and the shores of the North Sea were marked by
climatic stress during the fourteenth century, but Scandinavia also
suffered. As Pettersson puts it:
On examining the historic (data) from the last centuries of the
Middle Ages, Dr. Bull of Christiania has come to the conclusion that
the decay of the Norwegian kingdom was not so much a consequence of
the political conditions at that time, as of the frequent failures
of the harvest so that corn [wheat] for bread had to be imported
from Luebeck, Rostock, Wismar and so forth. The Hansa Union undertook
the importation and obtained political power by its economic
influence. The Norwegian land-owners were forced to lower their
rents. The population decreased and became impoverished. The revenue
sank 60 to 70 per cent. Even the income from Church property
decreased. In 1367 corn was imported from Luebeck to a value of
one-half million kroner. The trade balance inclined to the
disadvantage of Norway whose sole article of export at that time
was dried fish. (The production of fish increased enormously in
the Baltic regions off south Sweden because of the same changes
which were influencing the lands, but this did not benefit
Norway.) Dr. Bull draws a comparison with the conditions described
in the Sagas when Nordland [at the Arctic Circle] produced enough
corn to feed the inhabitants of the country. At the time of
Asbjoern Selsbane the chieftains in Trondhenaes [still farther north
in latitude 69 deg.] grew so much corn that they did not need to go
southward to buy corn unless three successive years of dearth had
occurred. The province of Trondheim exported wheat to Iceland and
so forth. Probably the turbulent political state of Scandinavia at
the end of the Middle Ages was in a great measure due to
unfavorable climatic conditions, which lowered the standard of
life, and not entirely to misgovernment and political strife as
has hitherto been taken for granted.
During this same unfortunate first half of the fourteenth century
England also suffered from conditions which, if sufficiently
intensified, might be those of a glacial period. According to Thorwald
Rogers[33] the severest famine ever experienced in England was that of
1315-1316, and the next worst was in 1321. In fact, from 1308 to 1322
great scarcity of food prevailed most of the time. Other famines of less
severity occurred in 1351 and 1369. "The same cause was at work in all
these cases," says Rogers, "incessant rain, and cold, stormy summers. It
is said that the inclemency of the seasons affected the cattle, and that
numbers perished from disease and want." After the bad harvest of 1315
the price of wheat, which was already high, rose rapidly, and in May,
1316, was about five times the average. For a year or more thereafter it
remained at three or four times the ordinary level. The severity of the
famine may be judged from the fact that previous to the Great War the
most notable scarcity of wheat in modern England and the highest
relative price was in December, 1800. At that time wheat cost nearly
three times the usual amount, instead of five as in 1316. During the
famine of the early fourteenth century "it is said that people were
reduced to subsist upon roots, upon horses and dogs, and stories are
told of even more terrible acts by reason of the extreme famine." The
number of deaths was so great that the price of labor suffered a
permanent rise of at least 10 per cent. There simply were not people
enough left among the peasants to do the work demanded by the more
prosperous class who had not suffered so much.
After the famine came drought. The year 1325 appears to have been
peculiarly dry, and 1331, 1344, 1362, 1374, and 1377 were also dry. In
general these conditions do little harm in England. They are of interest
chiefly as showing how excessive rain and drought are apt to succeed one
another.
These facts regarding northern and central Europe during the fourteenth
century are particularly significant when compared with the conclusions
which we have drawn in Earth and Sun from the growth of trees in
Germany and from the distribution of storms. A careful study of all the
facts shows that we are dealing with two distinct types of phenomena. In
the first place, the climate of central Europe seems to have been
peculiarly continental during the fourteenth century. The winters were
so cold that the rivers froze, and the summers were so wet that there
were floods every other year or oftener. This seems to be merely an
intensification of the conditions which prevail at the present time
during periods of many sunspots, as indicated by the growth of trees at
Eberswalde in Germany and by the number of storms in winter as compared
with summer. The prevalence of droughts, especially in the spring, is
also not inconsistent with the existence of floods at other seasons, for
one of the chief characteristics of a continental climate is that the
variations from one season to another are more marked than in oceanic
climates. Even the summer droughts are typically continental, for when
continental conditions prevail, the difference between the same season
in different years is extreme, as is well illustrated in Kansas. It must
always be remembered that what causes famine is not so much absolute
dryness as a temporary diminution of the rainfall.
The second type of phenomena is peculiarly oceanic in character. It
consists of two parts, both of which are precisely what would be
expected if a highly continental climate prevailed over the land. In the
first place, at certain times the cold area of high pressure, which is
the predominating characteristic of a continent during the winter,
apparently spread out over the neighboring oceans. Under such conditions
an inland sea, such as the Baltic, would be frozen, so that horses could
cross the ice even in the Far West. In the second place, because of the
unusually high pressure over the continent, the barometric gradients
apparently became intensified. Hence at the margin of the continental
high-pressure area the winds were unusually strong and the storms of
corresponding severity. Some of these storms may have passed entirely
along oceanic tracks, while others invaded the borders of the land, and
gave rise to the floods and to the wearing away of the coast described
by Pettersson.
Turning now to the east of Europe, Brueckner's[34] study 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.[35]
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.[36] 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.
As to the number of sunspots, there is little evidence previous to about
1750. Yet that little is both interesting and important. Although
sunspots have been observed with care in Europe only a little more than
three centuries, the Chinese have records which go back nearly to the
beginning of the Christian era. Of course the records are far from
perfect, for the work was done by individuals and not by any great
organization which continued the same methods from generation to
generation. The mere fact that a good observer happened to use his
smoked glass to advantage may cause a particular period to appear to
have an unusual number of spots. On the other hand, the fact that such
an observer finds spots at some times and not at others tends to give a
valuable check on his results, as does the comparison of one observer's
work with that of another. Hence, in spite of many and obvious defects,
most students of the problem agree that the Chinese record possesses
much value, and that for a thousand years or more it gives a fairly true
idea of the general aspect of the sun. In the Chinese records the years
with many spots fall in groups, as would be expected, and are sometimes
separated by long intervals. Certain centuries appear to have been
marked by unusual spottedness. The most conspicuous of these is the
fourteenth, when the years 1370 to 1385 were particularly noteworthy,
for spots large enough to be visible to the naked eye covered the sun
much of the time. Hence Wolf,[37] who has made an exhaustive study of
the matter, concludes that there was an absolute maximum of spots about
1372. While this date is avowedly open to question, the great abundance
of sunspots at that time makes it probable that it cannot be far wrong.
If this is so, it seems that the great climatic disturbances of which we
have seen evidence in the fourteenth century occurred at a time when
sunspots were increasing, or at least when solar activity was under some
profoundly disturbing influence. Thus the evidence seems to show not
merely that the climate of historic times has been subject to important
pulsations, but that those pulsations were magnifications of the little
climatic changes which now take place in sunspot cycles. The past and
the present are apparently a unit except as to the intensity of the
changes.
FOOTNOTES:
[Footnote 31: O. Pettersson: The connection between hydrographical and
meteorological phenomena; Quarterly Journal of the Royal Meteorological
Society, Vol. 38, pp. 174-175.]
[Footnote 32: A. Norlind: Einige Bemerkungen ueber das Klima der
historischen Zeit nebst einem Verzeichnis mittelaltlicher Witterungs
erscheinungen; Lunds Univ. Arsskrift, N. F., Vol. 10, 1914, 53 pp.]
[Footnote 33: Thorwald Rogers: A History of Agriculture and Prices in
England.]
[Footnote 34: E. Brueckner: Klimaschwankungen seit 1700, Vienna, 1891.]
[Footnote 35: For a full discussion of the changes in the Caspian Sea,
see The Pulse of Asia, pp. 329-358.]
[Footnote 36: S. Q. Morley: The Inscriptions at Copan; Carnegie Inst. of
Wash., No. 219, 1920.
Ellsworth Huntington: The Red Man's Continent, 1919.]
[Footnote 37: See summary of Wolf's work with additional information by
H. Fritz; Zuerich Vierteljahrschrift, Vol. 38, 1893, pp. 77-107.]