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| Figure 1. A Mayan temple (source) |
Every year, thousands of tourists flood to Central America to visit the ruins of the ancient Mayan civilisation. The pyramids, temples and monuments, which are today entangled in thick jungle vegetation, are only a glimpse of a once fruitful, sophisticated civilisation which possessed the knowledge of astronomy and mathematics, and crafted beautiful jewelry out of obsidian and jade. At the peak of their success, the Maya population in the Yucatan Peninsular, reached 13 million around 750 A.D. By 950 A.D, the population had significantly declined and their city, falling into ruin, was left in the hands of the jungle once again. To this day, this 'terminal Classic collapse' story remains a great mystery as to what drove the collapse of this successful, ancient civilization and this blog aims to explore the role of climate change in driving this collapse.
Haug et al. (2003) claims that the key behind this collapse story, lies in the geographical location of the Yucatan Peninsular. The Mayan lands fall between 17-22*N and is a seasonal desert receiving 90% of its rainfall between June and September, with a pronounced dry season throughout the rest of the year. Its rainfall patterns is driven mainly by the movement of the Intertropical Convergence Zone (ITCZ) which moves northwards in the summer bringing rain over Central America, and vice versa in the Winter months. As a result, the Maya built massive, sophisticated drainage systems throughout the cities, reservoirs on hilltops which used gravity to distribute the water, and complex irrigation systems. They were highly dependent on the movement of the ITCZ to replenish their freshwater supplies; a failure of this climatic phenomena could potentially have been catastrophic.
Haug et al. (2003) and later Peterson and Haug (2005) measured the concentration of titanium and iron elements from lake sediments and used them as a proxy for river discharge and changes in the hydrological cycle. They noted a long period of extended drought across Central America with multiple punctuation of intense drought periods centered around 810 A.D, 860 A.D, and 910 A.D, coinciding with the collapse of the Maya (figure 2). Peterson and Haug state that the significance of this discovery show how tightly couples the collapse of the Maya was to environmental constraints.
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| Figure 2. The titanium concentrations from the lake sediments identifying the terminal Classic collapse as a possible driver of the Mayan collapse (source) |
Diamond (2005), described the collapse as an 'ecocide' and suggests that the society destroyed the environment which the depended upon and essentially causing their own collapse. Environmental degradation is being highly blamed by Diamond as the Maya damaged their lands through intense agricultural practices including terracing, irrigation, deforestation and draining field. Over-reliance on a maize monoculture, a humid-climate which prevented the long-term storage of food, a lack of domesticated animals to aid with agriculture and a protein-poor diet, were also contributing factors, as was the lack of friendly neighbours and the highly structured, unequal, social hierarchy (Diamond, 2005).
This view by Diamond has been highly criticised, as many authors claim this view to be an environmental deterministic view. This is a concept which suggests that the physical environment sets a constraint on societal development, a concept which as Coombes and Barber (2005) show, has received much criticisms. It is seen as shifting the blame and responsibility behind collapse stories away from humans and onto a factor beyond our control. Furthermore, they claim that palaeoenvironmentalists are too ready to blame the collapse of a civilisation on climatic change solely based on an apparent correlation in the proxy record.
Hodell (2011) further this by stating an argument by highlighting the weaknesses of palaeoenvironemntal studies. The poor resolution and the inaccuracy in dating records are among the few factors contributing to the uncertainty and ambiguity in palaeoenvironmental records. As Aimers (2011) states, palaeoclimate data must be interpreted with care and the evidence is not robust enough yet to blame the collapse of the Mayan civilisation on climate change alone. A greater collaboration between climate scientists and archaeologists is needed (Aimers, 2011).
Collapse may not be the correct term to describe the decline in population or the abandonment of the Maya cities, as an increase in population was seen in other regions in Central America which suggests that some of the Mayan migrated away from these marginal areas to rehabilitate elsewhere (McAnany, 2010). It is clear that we cannot blame one single factor on the collapse of the Maya civilisation but that it was possibly due to multiple, cascading factors - an unstable society pushed by climate chang across their threshold and beyond stability. Although a dramatic depopulation did occur in some regions, seven million decendants of the once great Maya civilisation continue to live in remote villages across Central America. It was certainty not a complete obliteration (Gause, 2014).