A curious item
from a century ago in which notice is made of the plausible existence of a long
cycle between the seasons impacting the two poles which certainly conforms to
current experience. Note the clear
sailability of arctic waters during the medieval period. The item suggests that this is an
astronomical effect for which I know of no particular evidence unless everyone
is missing something.
The cycle itself
is centuries long and by that I mean around ten centuries. I think that the driver is the circum polar
current and an acceleration of cold water sinking into the deep in the South Atlantic.
The good news is
that we are in the warm part for a good while.
However in five centuries all bets are off.
In the meantime they appear to have got it more right than wrong first time out.
VARIATIONS IN
CLIMATE.
Press, Volume XLIV, Issue 6903, 8 November 1887,
Page 6
[By Alexander Bhc_, M.E.]
Many scientific men have" endeavoured to
explain the reasons of the great variations of climate in the prehistoric
times. Very clever and interesting suppositions have been made to elucidate the
matter. Some are based upon-facts lUte the secular change in the composition of
the earth, by itself or by cataclysm some are established upon probabilities of
variations from one time to another, in the of the constituents or elements of
our 1 neighbouring planets.
The most modern and tyest theory is founded on the
variable position of the earth in tbe course* of centuries towards the sun.
This has been studied specially by Jean Reynaud in his celeibrated book
"Ciel et Terre." Butnoonepf those three theories considered
separately, or combined together, can fully answer the following
question:—" Why, during the last geological period, the Arctic countries
were suddenly frozen after very likely a large flood?" The fact that
the.action was sudden is sufficiently proved t>v the preserved bodies of
fossil animals found with flesh and hair, as, for instance, the preglacial
elephant, called Mammoth, of which thousands and thousands are found in
Siberia.
If the phenomenon had not been of a sudden
character, we should find only the bones of them the other part would have been
destroyed by putrefaction.
As said, the last theory is founded upon the
variable, although regularly intermittent position, of the astronomical
systems. It does not fully answer the above question about a prehistoric
perturbation. Still, that theory is the best to explain the changes of climate
in the historical times. The calculations made on this basis are corroborated
by facts.
It is proved (says Jeanßeynaud)that 11,760 years
B.C. the warm and the cold seasons, so far as the sun is concerned, had their maximum
of difference in the Northern Hemisphere. Whence it follows that at that time
everything favoured the formation of glaciers.The summers were short and
extremely warm, the winters long and very cold. The quantity of caloric
emanating from the sun is the same every summer, but its action for the melting of
ice varies/when the skies are cloudy or not, consequently in several short
summers the melting may be different.
On the contrary, the formation of ice increases
annually if the winters are strongly cold, long and dark. The reverse of that
state of things is found by calculations for the year 1122 A.D., and it is
precisely at that time that we find the Danes and several Scandinavian nations
going, through the Arctic open seas.
Colonies are established by them in the highest
north latitude of Greenland, and the upper part of Nbrtll America, a long time
before Christopher Columbus had reached a more southern part of the same
continent. But those colonies were relinquished on account of the increasing cold.
In the fourteenth century the seas are found again closed, even in the summer.
The great north icefield (banquise) increases daily, the Arctic colonists are
compelled to come more to the south, and the cold takes possession again of
countries which were kept free for a few years just about the twelfth century.
Remains of those upper Arctic villages are found, I may say, in each Arctic
expedition. The ellmate of Iceland becoming more and more cool also proves that
the state of the earth varies in the course of centuries, regularly in
accordance with the above theory.
Of course, according to the reversed seasons of the
Southern Hemisphere, we must find the reversed facts There again the theory is
found correct. When Captain Cook followed in full the orders of the British
Government, to sail along the south ice-field as close as possible, he could
not.go lower than the 71st parallel, and ;he said to himself—" If there is
any land i under that latitude, itwill remain eternally unknown, because the
seas are closed and the dangers.are too great." This was said in 1773 and
ITI4. Still, in 1823 Weddell, the English'seal-fisher, went to within 74deg
15min, where Joe found the seas open. James Ross and Dumont d'Urvllle have
discovered since several antarctic lands far more southerly than was expected
possible by Captain Cook. As far as New Zealand is concerned, we may say with
great certainty that the country has been much cooler than it is now, and that
for several centuries in future it will become warmer and warmer. The same
theory seems to prove that all the attempts to reach the North Pole will be
more and more doubtful. If a Pole Is reached, we may say with some reason that
very likely the An tart ie Pole will be discovered before the North Pole, on
account of the decreasing of the southern ice-field corresponding with the
increase of that of the north.
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