Climate and human societies, from one crisis to the next: differences and similarities, from the Neolithic to the Middle Ages in central Anatolia
Résumé
While ice and sea cores provide global data (earth-wide or wide regions of the earth), continuous records in lake sediments are complementary, regional-scaled, records of regional-scaled climate changes. Records from deep lakes rarely suffer from chronological ruptures, with some exceptions caused by droughts, tectonism eruptions (intrusive gas, chemicals, and pyroclasts), inflow captures or karstic underground circulations… In the driest part of Central Anatolia however, lake sequences are rather shallow, thus possibly suffering from uncertain chronology. This is why using these lake records is delicate, although they present an extreme sensitivity to humidity depletion or changes (i.e. sensitive record trends), while human societies developed in plateaus and plains since the earliest Neolithic at the beginning the Holocene. The presentation will show how aridification phases can be evidenced, in timing and intensity, thanks also to a high quantity of 14C dates (> 100 dates) spanning the Late Glacial to the Middle Ages. We use these dates with the greatest care about possible reworking, length of time range, and possible wind or runoff erosion.
Our data contribute, not only to downscaling global and regional palaeoclimatic reconstructions into a human-scaled area, but also to stress and discuss: (1) the “humidity” element of the climate on the local scale (e.g. aridity increase/decrease; types of water-related ecosystems and associated resources), and (2) its connection with the “global/regional temperature data” provided by an abundant literature from ice, marine and deep (i.e. permanent) lake systems. Results also point to the prior importance of the locality of sequences studied in key-sectors of a composite terrestrial ecosystem, and of the multiplicity of records allowing evidence of time- and space-related connections between the records. In particular, the complementary nature and behaviors of these areas in the system, generate an apparent contradiction between results from the upper and lower parts of the system. For example, the center of the Bor plain has been rarely –if any- under water during the Late Holocene. In this context, results also enlighten discussions about linkages between archaeological sites and historical records on the one side, and environment/climate past records and local resources on the other side.
Finally, the results point to the necessity to set the word “collapse” in perspective of (a) the initial context of environment-human societies relationships (techniques, management, politics and policies ie. resilience) and possible pre-existing tensions within the society (stress accumulations), (b) the social, cultural and economic mechanisms (processes) giving birth and expansion to the so-called “collapse”, (c) the ways and timing of how the climatic change has impacted the society, and/or the various components of the society.