These magnificent volumes, the latest in the series of conference publications emanating from Halle, cover a topic—climate change around 2200 bc as a potential cause of cultural change—which is perhaps less well known to students of later prehistoric Europe than some other ancient environmental disasters. In many areas of the Old World there were striking developments in the later centuries of the third millennium bc, but they have not usually been attributed to changes in climate. The undertaking of studying it in these terms was therefore a challenging one, but one to which the articles in these volumes have contributed in exemplary fashion.

Forty-two chapters, several with multiple authors, and an Appendix showing a ‘Table of Events’, are included here; as a consequence, a short review can only point to some major themes that emerge from the volumes, rather than provide a full critique. Nine of the contributions are in German, the rest in English; the contributors come from almost all the major countries of Europe as well as North America. To have published such large and complex volumes within a year or two of the conference in question is itself a major achievement; and the usual high standards of Halle publications are evident in the excellent presentation of the books.

The 4.2 ka bp event, as the environmental change around 2200 bc is more correctly termed, is something familiar to students of ancient climate, less so to archaeologists (Andrew Fitzpatrick's contribution on Britain and Ireland, for instance, shows some bafflement about it). As Reinhard Jung and Bernhard Weninger explain, the most obvious aspect of it in the environmental record is evidence for widespread and persistent drought in many parts of the northern hemisphere, and a southward switch of the Intertropical Convergence Zone (ITCZ); these phenomena appear at many locations around the world, though not at high latitudes (e.g. Greenland, northern Europe). Archaeologically, the evidence from Mesopotamia has often been taken as exemplifying the situation, with major changes taking place, such as the end of the Akkadian empire, as Harvey Weiss explains.

How, then, did the conference organizers approach the topic? In looking at the list of contributions, it is striking that the great majority discuss the archaeological evidence in a wide range of locations in the Old World (from Ireland to Mesopotamia); only a few are by natural scientists. One might argue that such a book should start with a clear exposition of the environmental evidence for a major climatic event at 2200 bc; instead, one has to pick up the details from various of the papers presented.

One of the problems about identifying this phase of environmental change as an ‘event’ is that of chronological precision: many of the proxy data sources, as well as the archaeological ones, can be said to fall in the second half of the third millennium bc without being tied specifically to the decades around 2200. So Michele Massa and Vasif Şahoğlu give us an overview of the situation in Anatolia, concluding from a range of proxies that the ‘event’ may have occurred at different times ‘within the 2300/2200-1900 bc span’—hardly a single event. Helge Wolfgang Arz et al. likewise, looking for a consistent picture across the eastern Mediterranean region, can point to an early Holocene humid phase ending in the fifth millennium, but ‘a rather heterogeneous picture’ for the period between 2500 and 2000 bc—though in one of their Red Sea sediment cores there certainly is a marked change in calcium intensity and sediment type in the twenty-third century cal bc. When we turn to the European situation, Frank Sirocko shows that the 4.2 ka bp event was not associated with any of the known ‘Little Ice-Age-like events’, though there was a slight reduction of the annual temperature in the Alps. Since vegetation records and lake hydrology do not show the event, and no large volcanic eruptions are known from the period, it is most likely that any global phenomenon is the result of a reduction in the strength of the Pacific El Niño system. Sirocko's article is, however, highly informative when it comes to considering the possibility of a correlation between other catastrophic events in historical times (such as plague outbreaks) with climatic events; these would mainly result from extreme winters caused by solar irradiation minima. Alexander Land, Johannes Schönbein, and Michael Friedrich can point to several major events (very wet or very dry summers) in the fossil oaks of the Main Valley in the third millennium, but not one specifically in the twenty-second century, a situation similar to that in Ireland (Mike Baillie & Jonny McAneney). Andreas Bauerochse, Inke Achterberg, and Hanns Hubert Leuschner, looking at subfossil pines and oaks in Lower Saxony, detect a period of stress on trees in the period 2220‒2170 cal bc, probably caused by changing water tables and/or shifts in river discharge—both suggesting increased precipitation (though human influence, for instance by forest clearance, cannot be excluded). Walter Dörfler looks at pollen diagrams in the later third millennium along a transect across Europe from Greece to Poland and northern Germany, finding variable evidence for a shift around 2200, particularly in central and southern Germany; but the whole period was one of ‘environmental instability’ so a single driving force cannot be unequivocally proven. All this makes it less surprising that European later prehistorians have not paid much attention to 4.2 ka bp, and leads one to wonder if the ‘event’ was such a thing in Europe at all.

Turning to the archaeological discussions, Juan Carlos Moreno García sees no evidence for an externally caused crisis in Egypt at 2200 bc, rather a time of ‘deep changes’ and increasing integration into international trade networks; this is the direct opposite of what Felix Höflmayer states. Admittedly much depends here on Egyptian chronology, a perennially thorny problem. Various dates have been put forward by different scholars for the end of the Old Kingdom, but the results of Bayesian analysis of radiocarbon dates indicate a date in the twenty-fourth century, too early for the 2200 event. Hermann Genz shows that major transitions in the Levant occurred not at 2200 but at 2500 and 2000 bc. Evidence from Cyprus (Lindy Crewe) and the Aegean (Lorenz Rahmstorf) does not suggest any special crisis at this time either. At Troy (Stephan Blum & Simone Riehl), the change from Troy III to IV indicates no interruption, though agricultural conditions can be seen to develop during the course of the later third millennium; ‘slight drought stress signals’ can be detected on barley in Troy IV (early twenty-second century). By contrast, Jung and Weninger use statistical analysis of Blegen's pottery typology to show that there appears to be a gap between III and IV which, in their words, ‘has every chance of having been caused by a major “drought” event’ (p. 230). Their article is the fullest and most detailed in the entire volume, spanning a large geographical area (Anatolia to Sicily) and a large range of material culture objects. They use radiocarbon dates when they can, but in the Italian and Croatian contexts these are still rather few, and dates for (for instance) Cetina culture sites seem too early for their supposed contemporaries in the Aegean (Early Helladic III). Still, Jung and Weninger conclude that ‘further research into the impact of the 4.2 ka cal bp event on the late EBA [Early Bronze Age] cultures of the Mediterranean is likely to be rewarding’ (p. 230).

A group of papers is devoted to the situation in southern Europe. All of them review the archaeological evidence for the later third millennium bc, several noting that the period at or shortly after 2200 saw the transition from the Copper Age to the Early Bronze Age, but none can point to conclusive evidence for a climatic component. A French group led by Laurent Carozza point to a ‘new kind of management of the landscape and agro-pastoral areas […] undoubtedly under the control of a new elite that emerged around 2200‒2100 bc’ (p. 335). The well-known Barcelona group led by Vicente Lull point out that the fortified sites of the Late Copper Age in southern Iberia almost all came to an end by 2200, following which new economic and social structures came into existence—what they term a ‘profound social crisis’ (p. 389), though they admit there is no evidence for a rapid climatic change in the region at this time. Much the same can be said for Portugal (Antonio Carlos Valera) or central Spain (Germán Delibes de Castro and colleagues). Finally, a paper by Martin Kölling and Barcelona colleagues is entitled ‘No Indication of Increased Temperatures around 2200 bc in the South-West Mediterranean Derived from Oxygen Isotope Ratios in Marine Clams’, which rather speaks for itself.

Further north, Klára Fischl and colleagues describe 2200 bc not as a crisis period in Hungary, but a starting point for continuous, uninterrupted development, as Bell Beaker and Late Copper Age cultures gave way to full Bronze Age ones. François Bertemes and Volker Heyd point out that the date of 2200 cal bc may be arrived at in central European radiocarbon datings because of the shape of the calibration curve around this time, with no dendro dates for 100 years either side from any of the Alpine or sub-Alpine areas; continuity is just as evident as rupture in many parts of Europe. Matthias Merkl and Jutta Lechterbeck show from radiocarbon dates that there is a strong disjunction between Corded Ware and Bell Beaker sites around Lake Constance, less so between Bell Beaker and Early Bronze Age—the dates for which cluster around 2200 cal bc. Johannes Müller looks at various aspects of material culture (flint and metal daggers, barrow construction, house size, etc.) in three areas of northern Europe (Denmark, Schleswig-Holstein, and central Germany) and finds variability over time in all of them, but only in Jutland could cultural practices be related, potentially, to a crisis in productivity that might reflect the 2200 event.

Some contributions merely cover archaeological investigations concerned with the later third millennium cal bc, without specifically considering the 2200 event; the use of OxCal and Bayesian analysis of radiocarbon dates plays a large role in this. In some cases, the modelled dates do indeed indicate a visual correlation with the period in question: thus Madeleine Fröhlich and Matthias Becker, looking at the Saale-Unstrut area, show a marked change at 2200 cal bc from Bell Beaker to Early Bronze Age. One of the most interesting sites of this period is the extraordinary ‘sacred place’ at Pömmelte-Zackmünde, south-east of Magdeburg in the Elbe lowlands—described to me by Harald Meller as a Stonehenge ‘better than Stonehenge’. André Spatzier's article provides a short introduction to this Rondel site, with its multiple ditch, post, and pit rings, and pottery attributable to Bell Beaker and Early Bronze Age, with the modelled C14 boundary between the two cultural manifestations on the site lying at 2206‒2133 cal bc (the actual dates are not presented here). On any analysis, this is late for a Rondel, most of which fall considerably earlier (mostly fifth millennium bc). One wonders, incidentally, if the importance of the site, and the date range cited, acted as stimulants for the creation of a conference on the subject of 2200 bc?

So, was the 4.2 ka bp event responsible for major cultural changes in the Old World, or even for a collapse? The answer clearly depends on where you are looking, and what you consider evidence for a major change. In Mesopotamia many scholars, though not all, would accept a correlation between drought conditions arising c. 2200 cal bc and site abandonment around that time, leading to major changes in the political units in power. The situation in Anatolia and the Aegean is less clear, not least because of chronological uncertainties. These are magnified the further west one travels across the Mediterranean. In general, most authors in this volume espouse cultural change in their area in the second half of the third millennium BC, but few are willing to stick their necks out and see a correlation between cultural change and rapid climate change. No doubt a different book could be written if the area under consideration was a different part of the globe; but for Europe at least, the Klimasturz of 4.2 ka bp does not seem, on the evidence reviewed here, to be a profitable way to explain what was going on. Nonetheless, the volumes are a most valuable survey of the field, which can be expected to hold the field for many years to come.