Through my Twitter feed I was recently alerted to a new article published in PLOS-ONE entitled “Environmental Roots of the Late Bronze Age Crisis“, co-authored by D. Kaniewski, E. Van Campo, J. Guiot, S. Le Burel, T. Otto, and C. Baeteman, all of whom are geologists and/or environmental scientists working in France and/or Belgium. The authors argue that the collapse of various states in the eastern Mediterranean at the end of the LBA can be attributed to an environmental stimulus, specifically a 300-year drought. The new evidence for this argument is a core from the Larnaca Salt Lake near the important LBA site of Hala Sultan Tekke, which shows that the area slowly transitioned from a Mediterranean woodland to a dry steppe over the course of the LBA in two distinct steps:
The first step was recorded at 1450–1350 cal yr BC, and a second step was reached at ca. 1200 cal yr BC. The drivers of environmental changes for the second step are quite different as no fire activity or changes in the lagoon are attested. The agricultural activity, rich around the site, also strongly declined since 1200 cal yr BC. The PCA-biplot (Fig. 4) indicates that agriculture only became one of the main components of environmental dynamics since ca. 850–750 cal yr BC.
The authors then compare this development to Gibala-Tell Tweini in northwest Syria, where evidence for a long drought correlates with the core evidence from Larnaca. So the authors conclude that
Both proxies [Larnaca and Gibala-Tell Tweini] reveal a hydrological anomaly for the 1200–850 cal yr BC period, indicating a similar, although not uniform, drought event, recorded both on the island and on the continent. The onset of the drought event seems to be chronologically close to the LBA crisis and the Sea People event.
From this, their ultimate conclusion is that
this study shows that the LBA crisis coincided with the onset of a ca. 300-year drought event 3200 years ago. This climate shift caused crop failures, dearth and famine, which precipitated or hastened socio-economic crises and forced regional human migrations at the end of the LBA in the Eastern Mediterranean and southwest Asia. The integration of environmental and archaeological data along the Cypriot and Syrian coasts offers a first comprehensive insight into how and why things may have happened during this chaotic
period. The 3.2 ka BP event underlines the agro-productive sensitivity of ancient Mediterranean societies to climate and demystifies the crisis at the Late Bronze Age-Iron Age transition.
Here is where the authors and I part ways. My main problem lies in the gap between the first and second sentence. Even if we accept the modest conclusion that “the LBA crisis coincided with the onset of a ca. 300-year drought event,” why do we need to link the two causally? This is a post hoc ergo propter hoc-esque logical fallacy. This is especially so since we don’t have evidence for a large-scale drought. The two proxies they are using are under 250 km apart. This might seem like a long distance, but it’s positively tiny considering that they are using them to explain a collapse that spans the Greek mainland, Anatolia, the Levantine Coast, and Egypt. Mycenae on the Greek mainland, for instance, is about 1200 km away from Gibala-Tell Tweini in Northwest Syria, and almost as far away as the Hittite capital Hattusa, which is about 1000 km away from Egypt. Even if we were 100% sure about the 300-year old drought in Cyprus and Syria (unlikely given that we have only two proxies), can we really use the drought to explain the collapse of the Mycenaean political order some 1000 km away?
The rest of the concluding paragraph is, frankly, a guess. We don’t have evidence that allows us to claim, for instance, that “This climate shift caused crop failures, dearth and famine, which precipitated or hastened socio-economic crises and forced regional human migrations at the end of the LBA in the Eastern Mediterranean and southwest Asia.” Even worse is the claim that “The 3.2 ka BP event underlines the agro-productive sensitivity of ancient Mediterranean societies to climate” since it claims to show what it assumes. That is, the authors assume that drought led to collapse (I say assume because they don’t actually know that), then they claim that this shows that these societies were prone to collapse because of droughts! This is called begging the question.
I could go on and on, but I don’t want to belabor the point. The Mediterranean is climatically heterogeneous. Even if it weren’t, it is a huge stretch to assume that a drought in one part of the eastern Mediterranean can be used to extrapolate another drought elsewhere in the eastern Mediterranean. Even if it could, we can’t be sure that because the two “events” (they’re really processes, of course) are simultaneous or nearly so, that one explains the other. I’d concede that the drought contributes to our understanding of the collapse, but it’s simplistic to argue that this climate shift caused political collapse. In general, I’d add that the authors naively accept many archaeological and historical arguments as facts — the “Sea Peoples” are a big historiographical problem, for instance — and they clearly aren’t totally comfortable with the archaeological scholarship on this very difficult problem.
What all of this shows is the weakness of research that isn’t really interdisciplinary. If the authors really wanted to argue that climate and political collapse in the LBA were interrelated, they should have brought historians and archaeologists on board. They didn’t, and the results were as predictable as if I (an archaeologist of the Greek LBA) had tried to write an article interpreting their palynological analysis.