The Great Maya Droughts in Cultural Context: Case Studies in Resilience and Vulnerability

7: A Tale of Three Cities

127 DOI: 10.5876_9781607322801.c007 7 A Tale of Three Cities Effects of the AD 536 Event in the Lowland Maya Heartland Bruce H. Dahlin and Arlen F. Chase It was the best of times, it was the worst of times . . . —Charles Dickens, A TALE OF TWO CITIES Directly linking climate change and cultural change is difficult. However, it is occasionally possible to link extraordinary climatic events to the archaeological record. The AD 536 event is such an instance. Given its global reach, impact from the AD 536 event had to have been felt in the Maya area. The archaeological records of three of the most important Maya cities that have been excavated—Calakmul, Caracol,Tikal—may be used to examine this impact. Although the developmental trajectories of all three significantly changed in the mid-sixth century, their paths reveal the pursuit of divergent sociopolitical and economic strategies relating to subsistence, sustainability, and trade. The ad 536 eVenT Beginning in November AD 535, an atmospheric event variously described as a “dry fog” or “dust veil” descended on much of the world, all too often with catastrophic long-term consequences. Eyewitness documentary evidence comes from Sweden, Ireland, and England; throughout much of Italy and Carthage, in North Africa; and Byzantium, Mesopotamia, Mongolia, and China. Almost everywhere it was reported, it coincided with failed crops and famines, often combined with the spread of disease,wars,migrations, and toppled regimes. Indeed, the list of human catastrophes attributed to this short episode is truly astounding (Keys 1999): a three-year famine in Ireland; summer droughts 128 DAHLIN AND A. CHASE and frosts that killed 70 to 80 percent of the population in the Northern Kingdom of China (Houston 2000:73); the disintegration of the political regime in the Southern Kingdom of China; desiccation of the Mongolian steppes, causing the expulsion of the Avar warrior pastoralists, who then established an empire in eastern Europe that encompassed 1 million square miles; and the spread of bubonic plague by merchant ships from East African ports to the Mediterranean and northern Europe, thus contributing to the decline of the late Roman Empire. Although dates range from AD 533 to 539,paleoclimatologists have observed the onset of cold conditions in a variety of environmental indicators that include tree rings, ice cores, and stalagmites. Growth patterns in tree rings in Scandinavia, Siberia, Mongolia, Austria, the western United States, and Chile (Baillie 1995; Larsen et al. 2008) have demonstrated that retarded tree-ring growth persisted for as long as fifteen years. A stalagmite from Wanxiang Cave in northern China correlates the AD 536 event with an enormous spike in δ18 O (signifying dry conditions) (Zhang et al. 2008). It is not yet clear what caused this atmospheric disturbance. Some ice cores from Greenland and Antarctica exhibit peaks of sulfuric acid aerosols, implicating a huge volcanic eruption (Larsen et al. 2008),1 but other chemical analyses of spherules in a Greenland ice core suggest that the dust veil was caused by oceanic impacts of extraterrestrial bodies (Abbott et al. 2008; Baillie 2006). Regardless of the origin(s) of the dust veil, it is important to appreciate that the AD 536 event had a more potent impact on the atmosphere than any other volcanic eruption during the last three millennia (Larsen et al. 2008). Given the intensity, duration, and often devastating effects of this atmospheric disturbance throughout the Northern Hemisphere, the AD 536 event must have caused severe disturbances in both climate and cultural dynamics in the Southern Maya lowlands. First Approximation Scenario Evidence from the Southern Maya lowlands does, in fact, suggest substantial climatic change. A short but pronounced pulse of drought conditions is evident in sediment cores from Lakes Punta Laguna and Chichancanab circa AD 585 ± 50 (Curtis, Hodell, and Brenner 1996; see also Hodell et al. 2001) and from Lake Salpeten circa AD 500–550 (Rosenmeier, Hodell, Brenner, Curtis, and Guilderson 2002). In fact, the δ18 O values approximate those that mark the beginning of the eighth-century droughts that have been correlated with the earliest phase of the Terminal Classic collapse process.2 Higher A TALE OF THREE CITIES 129 sea-surface salinities reached marked minima in sediments from the northeastern Caribbean (Nyberg et al. 2001, 2002), indicating cooler sea-surface temperatures and drier periods in Mexico. Growth rings in a stalagmite from Macal Chasm cave in Belize also show a seventeen-year peak of aridity at...