New YorK AGRICULTURAL EXPERIMENT STATION. 443 
CHANGES IN CLIMATE. 
There is a widespread belief that climate is permanently change- 
able in long periods. That is, that regions are becoming perma- 
nently hotter or colder, or wetter or dryer. If there are such 
changes, the matter becomes of intense interest to the horticul- 
turist and the farmer; for a change in climate may force a change 
in horticultural or agricultural industries. 
In the twenty-five year period we have been considering we 
have seen that there have been several seasons in succession of 
moisture and dryness, of cold and warmth, and of frostiness and 
lack of frost. The pendulum seems to swing first to the right 
and then to the left, but approximately as far in one direction as 
the other. Each tree generation, excepting, possibly, the peach, 
lives through one or possibly several of these oscillations. But are 
these changes permanent? Our retrospect of twenty-five years is 
not long enough to establish permanency in weather changes, but 
climatologists seem to be agreed in regard to the matter. And so, 
without taking space to give data or the views in full of those who 
have studied climatic changes, the general belief of climatologists 
in this regard may be summarized as follows: 
It is well agreed that there have been climatic changes in the 
geological past; as periods of glaciers and periods of tropical heat 
in the latitude in which we live. Much evidence has been brought 
forward to show that there have been progressive and permanent 
changes in climate in the historic present. But such evidence when 
subjected to careful study has proved contradictory and unreliable, 
and it does not as yet seem to have been established that there are 
any considerable permanent changes in climate over large areas in 
historic times. It is now generally believed that periodic changes 
of climate are limited in time and not at all permanent. The causes 
of these periods of differing climate are generally ascribed to solar 
activity, but a satisfactory explanation of them has not yet been 
made. Neither the oscillations of climate nor the processes causing 
them are well understood. Contrary to popular belief, and possibly 
to former scientific belief, it is not now thought that man can 
greatly change climate by flooding or draining, by planting forests 
or by destroying forests, or in any way produce any important, 
long continued, or extended change in climate. 
