The study seems of have been on data specific to USA of that particular period & it self states that it doesn't relate to the world wide data. By early 20th ce

The study seems of have been on data specific to USA of that particular period & it self states that it doesn't relate to the world wide data. By early 20th century, scientists were in consensus on the effect of coal pollution on climate & have even written warnings for the future[1] as early as 1912. [1]:https://www.snopes.com/fact-check/1912-article-global-warming/ https://www.snopes.com/fact-check/1912-article-global-warmin...