Wednesday, April 28, 2021

History of Climate change II: a role for historians?

I read recently that the authoritive history of climate change studies is The Discovery of Global Warming ("this book is a history of how scientists came to imagine [climate change]") by Spencer R. Weart, an American physicist who retrained as a historian of science.

Browsing through Weart's Discovery, I find the quotation above is very precise. Weart's book is entirely about scientists.

Briefly, Weart reports that the role of greenhouse gases, particularly carbon dioxide, in keeping the earth's surface warm -- and the potential of their absence to bring on glaciation -- was established by John Tyndall in 1859. But most considerations of climate change continued to look to sunspots or orbital fluctuations. The possibility of human influence was discounted until the 1950s, when some California weather scientists and geochemists began to consider the possibility of human contributions to carbon-dioxide production. Concern about a human-driven rise in global temperatures were widespread enough by the 1990s to produce the Kyoto Accords on the reduction of carbon gas emissions. But conclusive confirmation of human-caused climate change, Weart reports, had to wait until 2001, with the publication of the famous "hockey stick" graph of global temperatures over a thousand years. The first edition of his book appeared in 2003.

Weart notes that a lack of communication of scientists in different diciplines long impeded research into the subject of climate change and its causes. What strikes me is how his book lacks any suggestion of communication between scientists and historians.

Historians have long been aware that climates change. The "little ice age" of the sixteenth and seventeenth centuries was familiar to European historians, and equivalant shifts had been observed elsewhere in the world. The French historian Emmanuel Le Roy Ladurie published "Histoire et Climat" in the journal Annales in 1959. His Times of Feast, Times of Famine: History of Climate Since the Year 1000 first appeared in French in 1967, drawing on many indicators from historical sources  (such as centuries of data on the advance and retreat of viable agriculture in the French Alps) as well as scientific sources (such as ancient tree ring analysis). 

Today environmental history thrives. Historical studies often make large speculations that climate change, including human-caused climate change, lay behind all sorts of historical changes. Did the population decline and consequent reforestation that followed the Black Death cause the Little Ice Age? Maybe. Did worsening climate doom the failed European settlement efforts in North America before 1600? Worth proposing. 

Now, Weart is probably right to assume that the scientists had to find their own way to measure global warming and its causes.  Historical studies could and did document changes in climate over time, but they did not identify causes for such changes. But a certain ambition for history was always there.  Emmanuel LeRoy Ladurie was part of a generation of historians who argued that history, far from being dependent on other disciplines, should be "the federative discipline," the one that brought the work of scientists, social scientists, and other scholars together to produce greater understanding.

Weart's book, a history of science with no interest in the history of historical studies, does not give support to that argument, let us say. There is no sense that historical studies did much to provoke the scientific curiosity about the causes of climate change that developed after 1950. So is environmental history -- history generally, if you like -- "federative?" Or mostly dependent?


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