This paper is one of many reviving the grizzled ghost of climatic determinism, an idea that originated in the 19th century, which attempts to explain complex social phenomena with simple phenomena like average temperature. For example, proponents of this theory argued that mean annual temperature is why colder regions were industrialized democracies, while the tropics were torpid and despotic. The story went (I am not making this up) that people at low latitudes can just laze around in hammocks and don’t have to go very far to find fruit, while people closer to the poles have to develop economies that coax food from the ground. This is only slightly racist, and climatic determinism went into hibernation as people realized that crank scientific theories have a way of developing into mass murder.
In the Büntgen et al. article, climatic determinism is the cause of good times, bad times, and wars. The core of the paper is a graphic showing tree‐ring reconstructed summer temperature and spring precipitation in central Europe for the last 2,500 years. Superimposed upon the figures are what the authors feel are salubrious times, given as the Late Iron age, the Roman Empire and the Medieval period, as well as bad ones. These include the “migration period” from 1,700 to 1,400 years ago, and the “modern migration” of the 19th century. Apparently people came to the U.S. because temperatures in Europe were a degree lower than average, rather than in search of economic and political freedom.
Looking at Figure 4 in the paper, it’s pretty clear that when it was warm in central Europe, times were peachy (literally), and when it was chilly there were wars, pestilences and other bad things.
This didn’t stop the authors from making a blatant political plea — completely unsupported by the results — nor did it prevent the editors from writing it out. Remember that this is a paper in which warm periods are good times. That notwithstanding, we read: