Here is the July average temperature in the USA from 1913-2013 (source: https://www.drroyspencer.com/2012/08/july-2012-hottest-ever-in-the-u-s-hmmm-i-doubt-it/):
"Zero" refers to the average temperature. We can clearly see a maximum in the time periode 1933-1938, corresponding to the Great Drought (Woody Guthrie's "dustbowl"). From 1938-1998, temperatures oscillated around a slightly negative value. Since 1998, increased temperatures are found as well as higher oscillation amplitudes, which is an alarming phenomenon. The relation between these data and climate changes as a result of CO2 emissions is not settled yet. Model calculations indicate that the drought in the 1930s is related to changes in the SST (sea surface temperature) in the Pacific ocean. The oscillations show that singular weather events do [u]not[/u] indicate climate changes.
