Discovering the Causes of the Ice Ages and Human-Caused Climate Change: a History of the Late Nineteenth and Early Twentieth Century

Abstract

Human-caused climate change is a contentious issue today among some non-scientific communities who argue that scientists support climate change because of their political beliefs. In contrast, some historians today argue that the carbon dioxide hypothesis, which says that increased carbon dioxide in the air increases global temperatures and that much of the increase in carbon dioxide is due to human causes, was not taken seriously during the early twentieth century. These contradictory views led to my investigation of the history of human-caused climate change, which originally evolved out of the search in the late nineteenth and early twentieth century to find a cause(s) of the ice ages. This thesis investigates early research into the origin of the ice ages, which generated fourteen hypotheses, including the carbon dioxide hypothesis. Historically, climate change research included contributions from many scientific disciplines: astronomy, chemistry, geology, meteorology, and others. The main challenge to finding the cause(s) of the ice age was the diversity and limitations of the evidence and the inadequate scientific instrumentation and theories in the early twentieth century, which explains why the plausibility of hypotheses by this problem-centered scientific community changed during this period, including the changing views on human-caused climate change. Still, progress was made and, 1950, only five hypotheses were still under consideration. Contrary to what some historians say today, the carbon dioxide hypothesis was treated like any other hypothesis, and there is no evidence that the scientific communities were biased against it. In addition, the criticisms that the carbon dioxide hypothesis received in the early twentieth century demonstrate that it was not always unquestioned by the scientific community, contrary to assertions made by some non-scientists today. However, there was less controversy surrounding the origin of the ice ages during this period.