(note the date of this presentation - it shows that people have taken note of changing temperature trends before)
Is Our Climate Changing? A Study of Long-Time Temperature Trends
By By J. B. Kincer, Weather Bureau, Washington, D.C., Sept. 29, 1933
The present wide-spread and persistent tendency toward warmer weather, and especially the recent long series of mild winters, has attracted considerable public interest; so much so that frequently the question is asked "Is our climate changing?" Historic climate has always been considered by meteorologists and climatologists to be a rather stable thing, in marked contrast to geologic climate and to weather. We know there have been major geologic changes in climate and that weather, which is the meteorological condition at any particular time, or for a short period of time, such as a day or a month, is far from stable. Different kinds of weather come and go in comparatively brief, alternating spurts, as it were, or with short periods of irregular length-cool or cold, then warm, and vice versa-succeeding one another with a continuous recurrence that everyone takes for granted. However, an exhaustive statistical examination of these short period temperature fluctuations fails to disclose any regularity that would afford a basis for forecasting future weather independent of the standard forecasting methods of the Weather Bureau, in which daily synoptic charts play an important role.
The phase of weather, or climate, that is attracting attention at the present time is not these short-period changes from warm to cool, and vice versa, for they are always present, but rather an apparent longer-time change to cool periods that seem to be less frequent and of shorter duration, and duration, and warm periods that are more pronounced and persistent. It has been thought that these fluctuations in temperature eventually neutralize one another, or smooth themselves out, when the long-time record is taken into account. In other words, meteorologists consider that climate, which is the normal run of the weather, for a long period of time, is a fairly stable thing, and that the average temperature for, say, any consecutive 20 years, selected at random from a long record, would not differ materially from that for any other consecutive 20 years so selected from that particular record. It appears, however, from the data presented with this study that the orthodox conception of the stability of climate needs revision, and that our granddad was not so far wrong, as we have been wont to believe, in his statements about the exit of the old-fashioned winter of his boyhood days. We are familiar with statements by elderly people, such as “The winters were colder and the snows deeper when I was a youngster”, and the like.
Read more and see graphs and tables at icecap.us