2026-05-18 カリフォルニア大学サンディエゴ校（UCSD）
＜関連情報＞
- https://today.ucsd.edu/story/scientists-uncover-centuries-of-climate-chaos-and-human-resilience
- https://www.sciencedirect.com/science/article/pii/S0277379126002374
完新世初期から中期にかけての東地中海における気候変動と文化変容 Early to mid-Holocene climate oscillations and cultural shifts in the eastern Mediterranean
Gilad Shtienberg, Richard D. Norris, Tammy M. Rittenour, Kendall Mahony, Kristen Plat, Steffen Mischke, Dafna Langgut, Assaf Yasur-Landau, Dorit Sivan, Miroslav Bárta, Thomas E. Levy
Quaternary Science Reviews Available online 13 May 2026
DOI:https://doi.org/10.1016/j.quascirev.2026.110028
Highlights
- We developed a centennial-scale Carmel coast wetland archive to document hydroclimate during the African Humid Period.
- This multi-proxy paleoclimate record identifies the magnitude and duration of wet and dry phases between 8 and 4 ka.
- The record captures the 8.2 ka event, progressive drying after ∼6 ka, and dry phases near 4.2 ka.
- The KRWL index distinguishes saline wetlands from true dry-soil phases in a Holocene coastal wetland system.
- No direct correlation was identified between environmental changes and settlement reorganization from 8 to 4 ka.
Abstract
The end of the African Humid Period in the mid- and late Holocene is associated with a shift to drier conditions along the Levant coast. Although Holocene hydroclimatic variability and arid events in the Levant have been widely studied, uncertainties remain regarding the rate, extent, and local expression of these changes, particularly at sub-millennial scales and in coastal wetlands. Questions also remain about how this environmental variability is intersected with patterns of human occupation and adaptation. To address this gap, we analyzed two sediment cores from the Kebara wetland on the Carmel coast of Israel spanning 8–4 ka. We developed the Kebara Relative Wetness Level (KRWL), a standardized multi-proxy index based on freshwater biota, pollen, seeds, charcoal, and total organic carbon (TOC). Pyrite and gypsum were evaluated separately to distinguish hydrochemical restriction within extant wetlands from true terrestrial dry-soil phases. The smoothed KRWL series ranges from −0.849 (terrestrial dry soil) to +0.995 (freshwater wetland) and defines four hydroclimate states: Wet (21.6%), Semi-wet (8.2%), Semi-dry (54.4%), and Dry (15.8%). The wettest interval, between 7.8 and 7.6 ka, coincides with the Holocene Climate Optimum and low δ18O values in regional speleothem records. KRWL captures the terminal expression of the 8.2 ka event near 8.0 ka, records a progressive decline in wetness after ∼6 ka, and identifies repeated terrestrial dry phases between 4.5 and 4.0 ka associated with the 4.2 ka drought. Comparison with archaeological trends at the Carmel coast and Be’er Sheva valley suggests that hydroclimatic deterioration formed part of the broader environmental context of settlement change, but does not demonstrate a direct deterministic climate–occupation link.
