Supporting Information

Butzer 10.1073/pnas.1114845109 Environmental Determinism and the Akkadian Collapse II/III period, whereas those of the subsequent Ur III-Isin-Larsa In 1911, Ellsworth Huntington (1) launched the hypothesis that phase more than doubled (ref. 17, figure 27). Archaeological degradation of the Mediterranean world and the decline of survey would therefore imply an increase, rather than decrease, Classical civilization were a result of desiccation (i.e., climatic of available water in the Euphrates basin from approximately aridification). This had led to nomadic expansion, attendant 2300 to 1600 BCE. It is implausible that the Akkadian heartland deforestation, and soil loss. Huntington (2) also claimed that collapsed because of a megadrought. periodic nomadic outbursts from central Asia were a result of Some science literature on the Tell Leilan event identifies a climatic fluctuations. Recourse to such “pulsations”—as pur- quasi-global paleoclimatic signal approximately 2100 BCE, claimed ported evidence for climatic cycles—has enjoyed great longevity. to be the most incisive of the Holocene record (8). However, Climatic change had become a major determinant in “decline.” whatever arid anomalies there were during the 600-y period after Determinism eventually fell into disfavor, but Harvey Weiss approximately 2500 BCE, they were of insufficient duration or and others (3) claimed that, after 2200 before common era intensity to leave a record in good-resolution pollen profiles of the (BCE), a mysterious “volcanic winter” of eolian ash triggered Near East (18, 19). Similarly, many hundred prime, global multi- a widespread environmental disaster lasting three centuries, proxy records fail to support this contention. What the most re- forcing abandonment of the early Bronze Age city of Tell Leilan cent research in the Mediterranean area and Near East does show in northeastern Syria and “collapse in the Aegean, Egypt, Pal- is that the Holocene record was marked by (i) a wet early Holo- estine, and the Indus” (4). This invocation of climate as a prime cene, with very rainy winters (11,000–7500 BP in calibrated years); mover was applauded by some hard scientists in favor of (ii) a drier, transitional mid-Holocene, with reduced seasonality a “Leilan Event” (in Upper Mesopotamia) and an Akkadian and bioclimatic oscillations, until 4000 BP; and (iii)atrendto collapse in the Euphrates floodplain (Lower Mesopotamia) as aridification and more contemporary conditions (11, 19). How- a consequence of abrupt climatic change. Bold correlations were ever, in central Asia and Anatolia, the early Holocene was arid, posited between peaks in deep-sea cores of the Arabian Sea, the mid-Holocene wet (16, 20). The observed isotopic shifts and wiggles in the stable isotopes of an Italian cave flowstone, or events fit comfortably into such a framework, without recourse to microstratigraphic identification of eolian activity in Nebraska, extreme anomalies or climatic change. as a global case for climatic forcing as a major agent of social fi change in distant Mesopotamia or Egypt (5–10). These papers Other Explanations. In short, the scienti c evidence does not show a nontrivial spread of 400 y for the beginning date, and support the hypothesis of a catastrophic megadrought as a prime suggest that hemispheric teleconnections remain premature. mover for collapse of either the Akkadian empire or a synergistic group of Near Eastern civilizations. What then does explain the Problems with Paleoclimatic Evidence. For one, the local environ- abandonment of Leilan? In the semiarid agricultural belt of mental evidence from Leilan (2) is unsatisfactory, and the au- eastern Syria, settlement patterns were dynamic, with urban thors have fundamentally changed their explanations several growth or settlement-cluster expansion in some areas, and times. Initially a volcanic winter was posited, but not supported ruralization or local abandonment in others, with no case for mass by a corresponding acid peak in Greenland ice cores (11). Traces migrations (21). In western Syria, a good number of cities were of volcanic glass in sediments at Leilan (4) are modest and destroyed, presumably by Akkadian military campaigns (ref. 22, limited to a very few profiles and levels. The authors sub- table 1). The desertion of Leilan coincided with this imperial sequently downplayed the pyroclastics, to opt for a megadrought unrest, which ended with disintegration of an internetworked caused by “massive smoke injection” from unverified “extensive world-economy, once extending from the Aegean to the Indus wildfires” that modified land/sea temperature gradients—a spe- Valley (ref. 22, pp. 280–287; and ref. 23). The triggering mech- cious explanation. More recently, the soils specialist of the anism was not a competition between farmers and pastoralists project abandoned the megadrought theory, arguing instead for (ref. 21, chap. 7; and ref. 24), but a relentless expansion of Akkad dust raised by the impact of an extraterrestrial body (12), a no- under Sargon or his grandson Naram-Sin that destroyed the tion that has found little support. The peculiar mineral grains entrepot role of Syria at the nexus of this economic system. The cited at nearby Tell Brak were found in a thin sediment lens checkerboard of destroyed cities suggests unbridled warfare, and below a structure built by the Akkadian ruler Naram-Sin much accumulated “capital” would have been lost, leaving the (∼2291–2255 BCE) (13). ability of the system to rebuild that capital severely impaired. Local, high-resolution isotope records, such as speleothems of Whether less destructive environmental stressors may have been Soreq Cave (Israel), have been invoked to argue for the mega- a coagency in regional transformation toward the end of the drought, but they suggest only minimal change after 2400 early Bronze age remains to be demonstrated by more careful BCE, whereas some earlier, wide divergences of the 18O and 13C sociohistorical and paleoclimatic analyses. isotope curves are difficult to explain for a complex cave envi- ronment (14). Instead, 13C isotopes from barley grains, a homo- Environmental Degradation and Human Impact geneous medium and from good archaeological contexts in Syria The links between deforestation and soil erosion were already (15), give consistently low negative values (i.e., drier climate) understood by Plato (∼370 BCE) (25), and the agronomist after approximately 2500 BCE and exhibit nothing extraordinary. Columella [∼65 common era (CE)] (26), who recommended The discharge of the Euphrates should be a key criterion for terracing of freshly cleared hillsides to avoid erosion. A modern such a regional megadrought. The isotopic and salinity records of development of these themes awaited George Perkins Marsh Lake Van, near its headwaters, do not support such an event (ref. (27) in 1864. Marsh was a leading conservationist who had ex- 16; despite lingering problems with a floating varve chronology). perienced clear-cutting in Michigan and later spent 20 y as Neither do settlement numbers and canal extensions in lower a traveler and diplomat in Italy and the Provence. He discussed Mesopotamia: the number of sites mapped for the Akkadian soil erosion and disastrous alluvial events, lamenting the impacts period increased 30% vs. that of the preceding early dynastic of what he regarded as slovenly Papist land use in the Mediter-

Butzer www.pnas.org/cgi/content/short/1114845109 1of6 ranean basin. Unlike Huntington, who blamed climatic change, velop and disseminate their analytical insights for realistic Marsh saw an impending destruction of the Mediterranean en- planning and practice at individual, state, and national scales vironment as anthropogenic. (42). An overall increase in forest cover is also supported by Although Marsh was influential for environmental conserva- historical evidence that woodlands in New South Wales today tion in the United States, a related thesis championed by Colonial are much the same as those reported by the earliest European officers of Britain and France gained preeminence in the Med- travelers, who had already encountered prehistoric gullies (43). iterranean orbit. As argued by Sarah Harris (28, 29), landscape The informal narrative of Collapse (39) revolves more around ecology was reduced to an agricultural–pastoral dialectic, or one an author’s opinions or advocacy than it does his stellar primary that cast “backward,” indigenous practices as implicit resistance research. The book can also be criticized for the offhand treat- to Colonial imposition of a more rational husbandry. In whatever ment of societal issues, which has been faulted in a book-length structural form, unsustainable resource management favors bi- counterpoint by leading anthropologists (44). otic degradation, soil loss, slope failure, and gullying or accel- erated alluviation. At more sophisticated diagnostic levels, it Further Considerations of Collapse introduces matters of scale, biotic mosaics, habitat complexity, The two analytical sketches appended here examine other Near and local cultural perceptions of resource impairment, pro- Eastern collapse scenarios to highlight the fundamental impor- ductivity, and stress (30). tance of social factors and the protracted rather than “abrupt” Unlike the climatic change model, the anthropogenic degra- time frames for collapse. dation counterpart has continued to evolve. It reemerged as “desertification,” to attract support from international agencies, Greco-Roman Fayum Oasis, Egypt. A different Near Eastern irri- but then generated controversy when its proponents failed to gation collapse illustrates the complexity of stability versus cu- appreciate the coagency of climatic anomalies in the Sahel or mulative decline. Under Ptolemy II (284–246 BCE) and Ptolemy Karoo (31, 32) or incorrectly diagnosed vegetation dynamics as III (246–221 BCE), the Macedonian dynasty that succeeded desertification in the Mediterranean world (33). With increasing Alexander the Great embarked on a major project of de- ideological undertones, anthropogenic degradation also became velopment and colonization in the Fayum depression of Egypt central to the 1492 polemic of Colonial despoliation of Latin (45–47). Rather than concentrate on building more local canal America (refs. 34, 35 vs. ref. 36), consistent with Marsh’s bias networks, Ptolemy II sought to control the inflow of Nile water against what he believed was improvident and destructive by an effective regulator dam, to drain part of the lake, reclaim Mediterranean land use (27). Unskilled application of such po- extensive marshlands, and greatly expand irrigation onto higher sitions in some examples of world-system history has also led to ground by outer rings of master canals (Fig. S1). Greek veterans oversimplification, dependence on inferior digests of environ- as well as Egyptians from the Delta were planted on the new mental evidence, and ignorance of culturally conditioned de- lands, focusing on strings of new towns, more than 40 of which cision-making (see ref. 37). have left informative archives of papyrus documents, ostraka, or Collapse and degradation has entered the global change de- codices (46) that vary in number over time from a flood to bate, and public interest in doomsday scenarios and apocalyptic a trickle. predictions appears to have grown since destruction of the World The Fayum colonies were first plunged into serious crisis during Trade Center. News media publish alarming scenarios that do not the Antonine plague of the late second century CE (87), which necessarily reflect mainstream scientific views. There is anxiety coincided with a long decline of Nile flood levels (see ref. 49). today, in an era of exceptional storms, rains, cold, heat, or drought The second crisis accompanied the Roman anarchy of the mid- that have resulted in major revision of official climate normals. In dle of the third century CE, at a time of continuing weak Nile effect, it has become popular to propose links between global floods. A number of new towns were now abandoned for several environmental change and unsustainable policies or practices that decades, but most were reoccupied, although shrunken in size. may be conducive to a cascade of overpopulation, degradation, Neglect of the peripheral master canals may also have been re- and societal collapse (38). sponsible. The third crisis began approximately 340 CE, leaving two of three master canals dysfunctional and at least eight towns Diamond Hypothesis. Jared Diamond’s comprehensive work Col- deserted. In one town (Karanis), local agriculture was no longer lapse (2005) (39) elegantly situates environmental mismanagement possible, and its citizens had to commute to work on farms of and unsustainable resource degradation as a potential agent of older communities (50, 51), implying that the water supply was collapse, in conjunction with factors like climate change. Among his inadequate. At least five more towns were abandoned in the historical examples, he singles out several societies as responsible fifth century, and the same number were abandoned again for unsustainable environmental damage, despite their modest, in the sixth, during times of bloody religious unrest between preindustrial technology. The papers of this PNAS Special Feature rival Christian denominations, but still before the Arab Conquest address a number of such cases, to show that the arguments over- (642 CE). During the next 300 y, there was some recovery, but in simplify much more complex social–ecological relationships, and the end, at least seven further sites were fully deserted, until Terry Hunt (40) dissects misunderstandings about the salient case renewed literary activity in Coptic or Arabic (47) suggests some of Easter Island, documenting intensification (lithic mulching) and qualified stabilization. remarkable indigenous resilience before slave hunters and in- The Fayum study is of interest because a diverse group of troduced disease destroyed that society. sources allows spatial representation of settlement abandonment The segment of Diamond’s Collapse (39) that is focused on or expansion during a hemicycle of collapse and partial recovery. contemporary problems also deals with some complicated issues Figure S2A illustrates a progressive desertion of most Ptolemaic in simplistic terms. Thus, the genocide in Rwanda is attributed to towns across some 700 years—at first tentatively (mid-third c.), “overpopulation,” despite specialist views that ground the un- then definitively (late fourth c.), with failure of most of the derlying ethnic hatred in the legacy of Colonial history. An item- original high canals before the time of the Conquest. All of the by-item critique of Collapse is offered by Jennifer Marohasy (41), new lands had been given up by the ninth c, as Christian set- who takes to task the chapter that places contemporary Australia tlements were retracted to the pre-Ptolemaic margins of culti- on the brink of destruction because of careless land manage- vation (Fig. S2B) (52–54). Depopulation probably reflects ment. With up-to-date information, she contradicts almost every unsuccessful Christian rebellions and inferred intrusion of claim in regard to agricultural decline, soil loss, salinization, or Muslim pastoralists. The refined hydraulic works (waterwheels, deforestation. In fact, rangeland managers in the Outback de- norias, watermills, masonry-lined canals) described by the active

Butzer www.pnas.org/cgi/content/short/1114845109 2of6 governor Nabulsi in 1245 CE (53–55), probably go back to an debris flows accumulated in small tributaries, stony colluvia swept earlier era, but despite his complaints about his predecessors, across the piedmonts, and 4 m of pottery-laden alluvium filled the agriculture was thriving again, judging by Nabulsi’s many listings valley bottoms. This dramatic mobilization of sediment was co- of palm groves, orchards, vineyards, or gardens. The population eval with late Axumite settlement (63), and a strong humic soil had been socially transformed, by adoption of fictive Arabian developed after stabilization, before the 12th century (64, 65). tribal identities (see 54). Yet the water supply was inadequate on Subsequent erosion at Axum was minor and localized. the northeastern and western margins of the oasis (56), where The exact sequence of politicoeconomic events marking Axum’s only wheat or barley were planted and villages were depopulated demise is unclear, but Sasanid Persia was contesting its commercial (54). What he did accomplish, as his manuscript points out, was role in Arabia and the Red Sea, and the city’shegemonyoverits to increase the ingress of flood waters by a newly designed reg- interior resources was breaking down. A king who died 630 CE had ulator at Lahun. faced rebellions, and was no longer buried in Axum (ref. 61, p. 93), A demographic high point is recorded in some detail by a land, implying that the elite had moved to new lands further south. settlement and tax-liability census of 1343 CE (57, 58) (Fig. S2C). However, some form of authority remained with the dynasty, be- 2 But with a cultivated area of ∼680 km , the cultivated area was cause, after a failed Axumite attempt to take Mecca in 703 CE, the still about 40% less than in 200 BCE. Between 1343 and 1800 CE Arabs blockaded and eventually destroyed Adulis. Cut off from its (the Napoleonic map and gazeteer) the number of settlements trading system and landlocked, Axum was increasingly deserted, had declined from 100 to 69, as a consequence of the Black and church tradition has Gudit, a tribal queen, razing the already- fl Death (1348-51) (59), Nile ood variation, and increasing mis- ruined city during the 10th century, perhaps symbolic of the re- D fi government, insecurity and disease. Figure S2 veri es a thin- newed dominance of pastoralism. New kingdoms now rose in the ning out of the settlement grid, a smaller number of large towns, interior of Ethiopia, although Axum retained its sacred role as the and partial desertion of the northeast and far south. A full return site of coronation for later kings. ∼ to early Ptolemaic prosperity was delayed until 1900 CE. In Axum documents the role of environmental variables in first A–E effect, this set of maps (Fig. S2 ) represents a cartographic facilitating an aggressive commercial power, and then under- illustration of collapse and recovery based on population and mining the resources of a polity on the defensive. However, more ecological change. than climatic anomalies, it was degradation that ruined the This Fayum narrative is about a royal project of agricultural environment and preconditioned Axum to collapse. Another expansion and urban development, beginning with innovations powerful trigger was the interruption of its trade, limiting Axum’s but continuing as a matter of successful management. Structural fl fl fl potential resilience. The scant two centuries between apogee and and Nile ood or in ow problems represented energy uxes and desertion suggest a vulnerable state, with little environmental or adjusting feedbacks. In the end, this curiously modern project political resilience. failed, and the Fayum returned to the status quo, bringing major population retraction, decreasing productivity, and presumed Bridge from Past to Present. Recent catastrophes such as the Crash human hardship. Probably the greatest ecological disaster in of 1929 and Great Depression were overcome by sociopolitical recorded Egyptian history, this Fayum breakdown might have solutions at large spatial scales. This poses interesting questions. been avoided by enlightened management, better security, and Did European societies cumulatively learn from the experiences greater technological innovation (56) at the national scale. of overcoming crises? Did technological innovation and in- dustrialization change the outcomes? Did increasing economic Axum, Ethiopia. For late Classical times, the literate civilization of integration raise the thresholds of systemic equilibrium? Such Axum on the northern Ethiopian plateau (61–63) offers an African example of collapse. Related archeology begins at approximately questions have no easy answers, but they offer more direct dia- 50 CE, and coinage serves to date the period to approximately 270 chronic perspectives for mitigation of impending global crises. to 630 CE. Ranked as one of the four world kingdoms in its time, For example, poor agricultural weather, compounded by Axum’s prestige was grounded in long-distance trade, with an livestock epidemics, created a famine disaster in 1315 to 1317 (66, 67). Extreme precipitation events in the 1340s (68) led to phe- economic network stretching from the Black Sea to south Asia. fl – Slaves, gold, iron, hides, and exotic products were obtained from nomenal oods, preceding the Black Death (1348 1349) and its echoes, to cause drastic depopulation, labor shortages, and de- the plateau or the Sudanese plains, to be channeled through Adulis, fl a gateway harbor on the Red Sea. ation (69, 70). In combination with soil erosion on marginal The Early Axumite phase, represented by plain stelae and lands, rural abandonment on a large scale saw 40,000 settlements decorated obelisks, continued until shortly after conversion of (19% of the total) deserted in Germany at approximately 1350 to king Ezana to Christianity at approximately 330 CE. Based on 1500 CE. The Black Death catastrophe was preconditioned by geoarchaeological study (63), a seasonally wetter climate favored extraordinary climatic anomalies and unequivocally triggered by slow erosion of clayey topsoil, which in the wake of strong floods a particularly deadly pathogen, both factors reinforced by famine and intensifying land use accumulated as dark, vertisolic sedi- and periodic recurrences. The result was a demographic break- ment on footslopes or black alluvium on valley floors. After an down, with distressing social and cultural repercussions. interruption without soil erosion, a new architectural landscape The array of natural disasters continued. Along the North Sea (middle Axumite) emerged, and under king Kaleb, Axum briefly coast from Flanders to Denmark, fierce but sporadic storm surges conquered Yemen at approximately 525 CE. With Axum at the drowned tens of thousands of people between 1164 and 1634 CE, height of its power, palaces and spacious mansions were built with the sea spilling 2 m over coastal dikes; large tracts were around the expanding city. However, the pillared mausoleum- permanently lost, leaving little more than a string of barrier is- church of Enda Kaleb records the beginning of a new phase of lands (71–75). Such extreme events had followed upon two more dramatic soil erosion: first a fine colluvium, followed by centuries of strong population growth, with settlement expanding a stony facies, and finally collapse rubbles. It appears that land into vulnerable environments and testing the limits of agricul- use pressures and perhaps a higher-amplitude climate were de- tural productivity. During Late Medieval times, settlement was nuding the hills above Axum (63–65), which, with an area of 75 in retraction from France to Poland. The Black Death, like ha, probably attained a population of more than 10,000, placing the introduction of Old World diseases to the western hemi- great stress on resources. sphere after 1492, can be considered as example of collapse. The late Axumite period, beginning as early as the late sixth The sociopolitical system of Western Europe was badly shaken century, brought a precipitous environmental decline. Massive but survived.

Butzer www.pnas.org/cgi/content/short/1114845109 3of6 Demographic growth only resumed in the 16th century, until poor dieval and Early Modern subsistence crises created great anxiety growing seasons and severe frosts created unprecedented famines at (e.g., witch burnings), impacting demographic pyramids, and trig- approximately 1570 to 1600, accentuated by interdiction of food gering extensive degradation. However, instead of collapse, fun- transports and declining soil fertility when livestock numbers were damental agricultural and economic transformations eventually reduced to grow more crops (69, 70, 76). But now there was no emerged under duress, in forms such as specialized stock raising, collapse. Traditional strategies began to be revised: stock raising improved farming (e.g., the “new husbandry”), technological in- was expanded but animals were stalled and fed with hay, and ma- novation, better communications, and internal or external migra- nure applied to crops and hayfields; roads were gradually improved tion. Cumulatively, such intensification represented a patchwork of to transport food to centers of famine. This montage of in- processes that spanned centuries and was accelerated by fresh en- tensification processes reduced mortalities and vulnerability to se- vironmental crises or social unrest. Change often came at a high vere Little Ice Age crises of the late 17th century. The last great societal cost, but rarely provoked breakdown, despite nutritional Europe-wide famine (1816–1817), as result of a catastrophic vol- stress and strong, long-term demographic fluctuations (77). That canic eruption in Indonesia, still saw great suffering and social is the overarching scenario of challenge and transformation in turmoil, but was eventually contained by long-distance food trans- Western Europe during more recent historical times. Change port (77, 78). Nevertheless, it set the tone for 19th-century eco- played out differently in specific areas, as based on experience, nomic migration to the New World. experimentation, innovation, information exchange, and a degree Driven by climatic perturbations, extreme interannual variability, of consensus. It involved both the grassroots and the elites, the open occlusion by volcanic ash, or plant and animal diseases, Late Me- questions being cybernetic, structural, and cultural.

1. Huntington E (1911) Palestine and its Transformation (Houghton Mifflin, Boston). 27. Marsh GP (1965) Man and Nature as modified by Human Action, ed Lowenthal D 2. Huntington E (1919) The Pulse of Asia (Houghton Mifflin, Boston). (Harvard Univ Press, Cambridge, MA). 3. Weiss H, et al. (1993) The genesis and collapse of third millennium north 28. Harris SE (2012) A Cypriot debate about ‘degraded landscape’ and ‘resilient Mesopotamian civilization. Science 261:995–1004. environment’ after Colonial intrusion. Proc Natl Acad Sci USA, 10.1073/pnas.1114085109. 4. Courty MA, Weiss H (1997) The scenario of environmental degradation in the Tell 29. Butzer KW, Harris SE (2007) Geoarchaeological approaches to the environmental Leilan region, NE Syria, during the late third millennium abrupt climatic change. Third history of Cyprus: Explication and critical evaluation. J Archaeol Sci 34:1932–1952. Millennium BC Climatic Change and Old World Collapse, eds Dalfes HN, Kukla G, 30. Butzer KW (2005) Environmental history in the Mediterranean world: Cross- Weiss H (Springer, Berlin), pp 107–148. disciplinary investigation of cause-and-effect for degradation soil erosion. J Archaeol 5. Sirocko F, et al. (1993) Century-scale events in monsoonal climate over the past 24,000 Sci 32:1773–1800. years. Nature 364:322–324. 31. Swift J (1996) Desertification: narratives, winners and losers. The Lie of the Land: 6. Cullen HM, et al. (2000) Climate change and the collapse of the Akkadian empire: Challenging received Wisdom in Africa, Environmental Change and Policy, eds evidence from the deep sea. Geology 28:279–282. Leach M, Mearns R (James Curray, Oxford), pp 73–90. 7. deMenocal PB (2001) Cultural responses to climate change during the late Holocene. 32. Hoffman MT, Bond WJ, Stock WD (1995) Desertification of eastern Karoo, South Science 292:667–673. Africa: Conflicting paleoecological, historical, and soil isotopic evidence. Environ 8. Thompson LG, et al. (2002) Kilimanjaro ice core records: Evidence of Holocene climate Monit Assess 37:159–177. change in tropical Africa. Science 298:589–593. 33. Grove AT, Rackham O (2001) The Nature of Mediterranean Europe: an ecological 9. Booth RK, et al. (2005) A severe centennial-scale drought in mid-continental North History (Yale Univ Press, New Haven, CT). America 4200 years ago and apparent global linkages. Holocene 15:321–328. 34. Butzer KW, ed (1992) The Americas before and after 1492: Current Geographical 10. Drysdale RG, et al. (2006) Late Holocene drought responsible for collapse of Old Research. Ann Assoc Am Geographer 82:343–568. World civilizations is recorded in an Italian cave flowstone. Geology 34:101–104. 35. Butzer KW, Butzer EK (1997) The ‘natural’ vegetation of the Mexican Bajio: Archival 11. Wanner H, and others (2008) Mid- to late Holocene climate change: an overview. documentation of a 16th century savanna environment. Quat Int 43/44:161–172. Quat Sci Rev 27:1–38. 36. Simon J (1997) Endangered Mexico: An Environment on the Edge (Sierra Club Books, 12. Courty MA (2001) Evidence at Tell Brak for the Late ED III/Early Akkadian air blast San Francisco). event (4 kyr BP). Excavations at Tell Brak, vol. 2, Nagar in the Third Millennium BC, eds 37. Chew SC (2001) World Ecological Degradation: Accumulation, Urbanization and Oates D, Oates J, McDonald H (Oxbow, Oxford), pp 367–372. Deforestation 3000BC–AD 2000 (Altamira, Lanham, MD). 13. Oates D, Oates J (2001) Archaeological reconstruction and historical commentary. 38. Russell C, Russell WMS (1999) Population Crises and Population Cycles (Galton Excavations at Tell Brak, vol. 2, Nagar in the Third Millennium BC, eds Oates D, Institute, London). Oates J, McDonald H (Oxbow, Oxford), pp 379–396. 39. Diamond J (2005) Collapse: How Societies Choose to Fail or Succeed (Viking, New 14. Bar-Matthews M, Ayalon A (2004) Speleothems as palaeoclimate indicators: A case York). study from Soreq Cave located in the Eastern Mediterranean region, Israel. Past 40. Hunt TL (2007) Rethinking Easter Island’s ecological catastrophe. J Archaeol Sci 34: Climate Variability through Europe and Africa, eds Battarbee RW, Gasse F, Stickley CE 485–502. (Springer, Dordrecht, The Netherlands), pp 363–392. 41. Marohasy J (2005) Australia’s environment undergoing renewal, not collapse. Energy 15. Riehl S (2008) Climate and agriculture in the ancient Near East: A synthesis of the Environ 16:451–480. archaeobotanical and stable carbon isotope evidence. Vegetation Hist Archaeobotany 42. Stafford Smith DM, et al. (2007) Learning from episodes of degradation and recovery 17(suppl 1):43–51. in variable Australian rangelands. Proc Natl Acad Sci USA 104:20690–20695. 16. Wick L, Lemcke G, Sturm M (2003) Evidence of Lateglacial and Holocene climatic 43. Butzer KW, Helgren DH (2005) Livestock, land cover and environmental history: The change and human impact in eastern Anatolia: High-resolution pollen, charcoal, Tablelands of New South Wales, Australia, 1820-1920. Ann Assoc Am Geogr 95: isotopic and geochemical sediments of Lake Van, Turkey. Holocene 13:665–675. 80–111. 17. Adams RM (1981) Heartland of Cities: Surveys of Ancient Settlement and Land Use of 44. McAnany PA, Yoffee N, eds (2010) Questioning Collapse: Human Resilience, Ecological the Central Plain of the Euphrates (Univ Chicago Press, Chicago). Vulnerability and the Aftermath of Empire (Cambridge Univ Press, New York). 18. Bottema S (1997) Third millennium climate in the Near East based upon pollen 45. Mueller K (2006) Settlements of the Ptolemies: City Foundations and Town evidence. Third Millennium BC Climate Change and Old World Collapse, eds Foundations in the Hellenistic World. Studia Hellenistica 43 (Peeters, Leuven, Dalfes HN, Kukla G, Weiss H (Springer, Berlin), pp 489–515. Belgium). 19. Vannière B, and others (2011) Circum-Mediterranean fire activity and climate change 46. Leuven Fayum Database (2003) http://fayum.arts.kuleuven.ac.be. during the mid-Holocene environmental transition (8500-2500 cal. BP). Holocene 21: 47. Bagnall R, Rathbone DW (2005) Egypt from Alexander to Early Christians: An 53–73. Archaeological and Historical Guide (British Museum, London). 20. Chen F, et al. (2008) Holocene moisture in arid central Asia and its out-of-phase 48. Duncan-Jones RP (1996) The impact of the Antonine Plague. J Roman Archaeol 9: relationship with Asian monsoon history. Quat Sci Rev 27:351–364. 108–136. 21. Arne W (2009) Challenging Climatic Change: Competition and Cooperation Among 49. Bonneau D (1971) Treasury and Nile: Incidences of Nile Flood Irregularities in Treasury Pastoralists and Agriculturalists in Northern Mesopotamia (c. 3000-1000 BC) Records of Greek and Roman Egypt (French) (Editions Cujas, Paris). (Sidestone, The Hague). 50. Van Minnen P (1995) Deserted villages: Two late-antique townsites in Egypt. Bull Am 22. Butzer KW (1997) Sociopolitical discontinuity in the Near East c. 2200 BCE: scenarios Soc Papyrologists 32:41–56. from Palestine and Egypt. Third Millennium BC Climate Change and Old World 51. Keenan J (2003) Deserted villages: From the Ancient to the Medieval Fayum. Bull Am Collapse, eds Dalfes HN, Kukla G, Weiss H (Springer, Berlin), pp 245–296. Soc Papyrologists 40:124–137. 23. Warburton DA (2001) Egypt and the Near East: Politics in the Bronze Age (Civilisations 52. Evetts BTA, Butler AJ (1895) The Churches and Monasteries of Egypt and some du Proche-Orient, Neuchatel, Switzerland), IV Histoire-Essai 1. neighboring countries, attributed to Abu Salih the Armenian (Gorgias Press, New York). 24. Fall P, Lines L, Falconer SE (1998) Seeds of civilization: Bronze Age rural economy and 53. Zeki A (1899) An Arabic description of the Fayum (7th century of the Hegira) (French). ecology in the Southern Levant. Ann Assoc Am Geogr 88:107–125. Bull Soc Geographie de l’Egypte 5:253–295. 25. Plato, Timaeus and Critias, trans Lee HDP (1971) (Penguin, London). 54. Salmon G (1901) Geographical inventory of the Province of Fayum after An Nabulsi 26. Columella, On Agriculture, trans Ash HB (1941) (Heinemann, London). (French). Bull Inst Francais d’Archéologie Orientale, Cairo 1:29–77.

Butzer www.pnas.org/cgi/content/short/1114845109 4of6 55. Keenan J (1999) Fayyum Agriculture at the End of the Ayyubid era: Nabulsi’s Survey. 66. Grigg DG (1980) Population Growth and Agrarian Change: An Historical Perspective in Agriculture in Egypt from Pharaonic to Modern Times, eds Bowman AK, Rogan E. (Cambridge University Press, London). Proc Brit Acad 96:287–299. 67. Kershaw I (1973) The Great Famine and agrarian crises in England 1315–1322. Past 56. de Sacy S, trans. ed (1810) State of the provinces and villages of Egypt. in Account and Present 59:3–50. of Egypt by Abd-Allatif, Arab doctor of Bagdad (French) (Imprimerie Imperiale, Paris), 68. Dotterweich M (2005) High resolution reconstruction of a 1300 year-old gully system pp 593–703. in northern Bavaria, Germany, as a basis for modeling long-term man-induced 57. Kraemer B (2010) The meandering identity of a Fayum canal (Am Studies in landscape evolution. The Holocene 15:994–1005. Papyrology, Ann Arbor MI), pp 365–376. 69. Abel W (1986) Agricultural Fluctuations in Europe from the Thirteenth to the 58. Hahn H (1979) Agypten nach den mamlukischen Lehensregistern, Tübinger Atlas zum Twentieth Centuries (Methuen, London), 3rd ed. Vorderen Orient, Beiheft B38/1. 70. Pfister C (1984) Population, Climate and Agrarian Modernization 1525–1860 59. Borsch SJ (2005) The Black Death in Egypt and England: a Comparative Study (German), v. 2 (Paul Haupt, Stuttgart). (University of Texas Press, Austin). 71. Lamb HH (1991) Historic Storms of the North Sea, British Isles and the North Sea 60. Bonneau D (1993) The Administrative System of Nile Waters in Greek, Roman and (Cambridge University Press, London). Byzantine Egypt (French) (Probleme der Ägyptologie 8, Brill, Leiden). 72. Pfister C, Brazdil R, Glaser R, eds (1999) Climatic Variability in Sixteenth Century 61. Munro-Hay S (1991) Aksum: An African Civilisation of Late Antiquity (Edinburgh Europe and its Social Dimensions (Springer, New York). University Press, Edinburgh). 73. Lambert AM (1985) The Making of the Dutch Landscape (Academic Press, London), 2nd ed. 62. Phillipson DW (2000) Archaeology of Aksum, Ethiopia, 1993-7 (Oxbow Books, Oxford 74. Gottschalk MKE (1971–77) Storm Surges and River Floods in the Netherlands (Dutch) UK), 2 vol. (Assen, Gorkum, Netherlands, 1–3). 63. Butzer KW (1981) Rise and fall of Axum, Ethiopia: A geo-archaeological 75. Butzer KW (2002) French wetland agriculture in Atlantic Canada and its European interpretation. Am Antiquity 46:471–495. roots. Ann Assoc Am Geographers 92:451–470. 64. Lamb HF, Leng MJ, Telford RJ, Ayenew T, Umer M (2007) Oxygen and carbon isotope 76. Clark P, ed (1985) The European Crisis of the 1590s (Allen and Unwin, London). composition of authigenic carbonate from an Ethiopian lake: a climate record of the 77. Schofield RS (1985) The impact of scarcity and plenty on population change in last 2000 years. The Holocene 17:517–526. England. Interdisciplinary Hist 14:265–291. 65. Dramis F, Umer M, Calderoni G, Haile M (2003) Holocene climate phases from buried 78. Post JD (1977) The Last Great Subsistence Crisis in the Western World (Johns Hopkins soils in Tigray (northern Ethiopia): comparison with lake level fluctuations in the main University Press, Baltimore MD). Ethiopian Rift. Quat Res 60:274–283.

Fig. S1. Environmental context for Egypt’s Fayum Oasis. Irrigation was coupled with the course of Greco-Roman colonization and abandonment. For in- terpretation, see Fig. S2 A–D. Based on multiple sources, satellite imagery, and field observations.

Butzer www.pnas.org/cgi/content/short/1114845109 5of6 Fig. S2. Collapse and Recovery in the Fayum Oasis. With failure of the Ptolemaic master canals during Late Roman times (A), more than half the cultivated land was abandoned. Surviving Coptic Christian settlement towards 800 CE had been reduced to a much smaller, internal canal system (B). Population and productivity greatly increased in High Islamic times to 1300 CE (C) but cultivated land was ~40% less than in 2nd c. CE. After the Black Death (1348 CE) setllement number declined permanently and mismanagement left 10% of the land deserted (D). Changing shoreline positions of the lake are unknown. See text.

Butzer www.pnas.org/cgi/content/short/1114845109 6of6