Resilience and Vulnerability of Southeast Asian Societies to Climate Variability in the Pre-Modern Era

Abstract:

Climate variability and projected future climate change has led to growing interest in understanding societal responses to changes in environmental conditions, and identifying societies that are particularly vulnerable or resilient to external shocks. To investigate this question it is instructive to look into the past, where we have examples of civilizational decline that have been hypothesized to be linked to climate variability or change. The Khmer Empire of the late 1^st and early 2^nd Millennium AD is an excellent example of a society that may have been affected by climate: After constructing the world’s largest urban area in pre-modern time at Angkor, the site was largely abandoned after ~600 years of occupation. To investigate the vulnerability and resilience of Southeast Asian societies and test hypotheses about the importance of climate impacts on societies, I developed a new process-based model of human subsistence and demography for preindustrial Southeast Asia. The model is driven by topography, soils, vegetation and climate, and accounts for the range of subsistence lifestyles that were present at the time, from semi-nomadic shifting cultivators to complex irrigation-based urban polities. I use high-resolution gridded climate reconstructions from the Southeast Asian Drought Atlas to modulate the baseline climate input data and simulate the effects of periodic drought on potential food production and overall landscape-level carrying capacity. Results show that subsistence lifestyle may have had a large influence on the vulnerability or resilience of a society to climate variability. Complex societies with a large built infrastructure were more vulnerable to excessive rainfall as opposed to drought, while drought most affected small-scale sedentary farming communities that lacked trade networks for basic foodstuffs. Shifting cultivators could generally survive periods of unfavorable climate by concentrating more on foraging to collect food as opposed to crop harvests. Initial results suggest that a combination of floods that damaged infrastructure, followed by drought that affected food production may have been at least in part responsible for the decline of the Angkor society.