Midcentury Global Cooling
What explains the 1940–1975 cooling trend?
In one of my first articles, I addressed the change in ice cover observed on lakes as a result of a warming climate. In response to that article, I received a disparaging email claiming that scientists can’t make up their minds, and once thought the planet was cooling and heading into an ice age.
Since this isn’t the first time I have heard, “scientists changed their minds”, I thought it was important to explain what actually happened during this time to try and dispel this myth.
The global temperature was declining from 1940–1975 (Figure 1); this is a fact. The drop was slight, about 0.1°C over the 35 year period, and was sandwiched between two warming periods. However, this cooling was only observed in the Northern Hemisphere (Damon and Kunen, 1976). The Southern Hemisphere was actually warming. This is an important piece of evidence that I’ll circle back to.
