Scientifique_.

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MODIFICATION OF OUR CLIMATE.

By JOSEPH WALLACE.


Every now and then some weather sage predicts extremely cold winters,
and another ventures to say that the sun is gradually losing heat and
in time Arctic cold will prevail over the globe. Whatever may have
been the changes during the vast cycles of time prior to the advent of
man, or whatever may be the changes in the time to come, one thing is
quite certain; that our climate has been much modified within the past
two or three thousand years.

"There have been fifteen climatic changes since the beginning of the
glacial age, each change lasting 10,500 years, and each change
reversing the season in the two hemispheres, the pole which had
enjoyed continuous summer being doomed to undergo perpetual winter for
10,500 years, and then passing to its former state for an equal term.
The physical changes upon the earth's surface during the past 80,000
years modified the changes of climate even in the Arctic regions, so
that the intense cold of the former epochs was much modified during
the latter epochs." Reckoning these climatic changes in their order,
we had entered the epoch of a more genial temperature about fifteen