A climate for social change

Abstract

It's probably only fair that Nature should publicize the views of a historian about meteorology, because in the past it has published influential letters by meteorologists on history. Lewis Fry Richardson demonstrated that differential equations and statistical laws that can successfully model weather systems should also be able to model humans' behaviour and maybe even psychology, from their proclivity for conflict to their appreciation of jazz. This approach not only explains quantitatively how wars did or did not develop, but in 1935 and 1951 predicted future developments (see Nature 411, 737; 2001). Lucian Boia, a historian at the University of Bucharest in Romania, has written a stimulating book, The Weather in the Imagination, reviewing the literature on theories of how climate has affected societies, and of how humans may have influenced climate. He concludes with a personal, if not entirely accurate, account of the science of human-induced climate change, and debates the current policy options. He reveals his methodological bias, however, when he implies that Newton's work on predicting the movement of planets is a rather simple matter compared with studying the complexity of history. (Richardson, in contrast, had noted that, like the natural world, societies can in some respects have simple mathematical descriptions, for example in the way that armaments can grow exponentially before a war, and that the frequency of conflicts tends to follow a Poisson distribution.) The big historical question in this book the extent to which national characteristics are determined by the weather and climate has been addressed in fascinatingly different ways by Hippocrates, historian Edward Gibbon, French philosopher Montesquieu, the Arab historian Ibn Khaldun, and more recently by Hubert Lamb and Emmanuel Le Roy Ladurie. Much of the evidence is anecdotal and rather surprising. The Greeks thought that the cold weather made the British not only aggressive but sexually promiscuous obviously the directors of recent reality TV shows could have saved themselves a lot of money by staying in Britain, if only they had read their Hippocrates. Gibbon extended this climate hypothesis by arguing that people from northern Europe had also been influenced by the way they modified their climate through deforestation and agriculture. Some writers included real weather observations: the Venerable Bede in the eighth century included in his chronicle a now well known statistical forecast: "Red sky at night is a shepherd's delight." Montesquieu, in contrast, studied the taste buds of sheep's tongues and their blood circulation at various temperatures, and concluded that northern people were bold and not very devious or sensitive compared with those from lower latitudes! This kind of thinking and eccentric collection of data continued until the early twentieth century when geographers, historians and anthropologists pointed out that societies evolve as much through organization and religion, for example, as through climate. Boia brings a topical dimension to his perspective when he emphasizes the relation between the way societies have dealt with climatic events and with natural disasters. In their reactions to the sudden loss of life and disruption associated with the latter, most societies have sought religious explanation. The Bible and other early writings focused on whirlwinds, fire, earthquakes, floods and droughts. They also revealed how various kinds of 'divine intervention' have helped or hindered the hazard, depending on the point of view: the Japanese, for example, are grateful for the 'kamikaze' typhoon that saved them from Genghis Khan. The ice age was the last globally significant climate change that humans endured. It was also a natural disaster of huge proportions as the ice retreated some 10,000 years ago. This shaped the landscape of Britain and was probably associated with floods in the Middle East, India and the northwestern United States (where the mythical raven god carried people away on its wings). This extreme form of climate change was feared by religious alarmists to be imminent at the start of the sixteenth century. This led the president of the Toulouse parliament in France to use the famous woodworking skills of the region to build another ark. According to the Michelin guide, these skills later led to the Lagard{è}re media company and Airbus. In the concluding chapter on climate change, Boia sides with Bj{ø}rn Lomborg in suggesting that a 2 C change in global temperature is of no great concern. A conference of meteorologists held in Exeter, UK, in February disagreed, concluding that such an outcome would be unacceptable to most societies if they had a choice in the matter. Boia himself points out that such a rise in temperature will lead to the loss of mountain glaciers and the destruction of millions of species of plants and animals. He makes a technical error, however, in stating that the reduction of emissions needed to mitigate this rise can be provided solely by the more economical and efficient use of transport. These steps, although necessary, are insufficient: the excessive use of energy for heating and cooling buildings, which in most countries gives rise to 50{%} of emissions, also needs to be curbed. Lomborg is correct that the local environment and living standards are improving for many people. But some climate models would see people reduced to communities perched on hilltops in a depleted natural environment. Some of us might be living on the water in the next generation of ark, indeed the Netherlands is planning to develop floating houses for use in the most flood-prone areas of the country. An alternative reading of history might conclude that human societies can rise to extraordinary challenges, as the 3,000-year-old society of China surely demonstrates, and should therefore be able to avert the climatic consequences of our actions and prevent their worst effects. Unfortunately that is not the message of this important book.