UC San Diego

The unusually warm and wet climatic conditions associated with the African Humid Period (AHP) from 6,000 to 11,000 years ago are well recorded across the Mediterranean. The termination of the AHP is widely considered to be “abrupt”, transitioning into modern, seasonally dry climatic conditions over the course of 500-800 years. This was not a smooth transition, but was punctuated by short-term, extreme climatic fluctuations of both wetter and drier conditions that are not well defined. These short-term variations in climate can drastically alter vegetation patterns, water availability, and overall habitability of lands. We have conducted a multi-proxy analysis of a sediment core from the Kebara Marshes of Israel, reconstructing the paleoenvironmental conditions of the mid- to late Holocene. By identifying the depositional environments of the five repeating, distinct facies in our core, we were able to infer the relative wetness of the climatic conditions during those times. We recorded the overall drying trend associated with the termination AHP as well as decadal-resolution variability throughout. Our study finds that aridity begins to substantially increase ~7.0 ka until modern, seasonally dry conditions first appear ~6.3 ka. Within each dominant climatic regime, dramatic multidecadal climatic fluctuations occur about once per century. During the mid-Holocene, the cultural shift from nomadic hunter-gatherers to the first settled societies occurs across the Levant. Defining these rapid climatic variations can ultimately provide insight into major cultural shifts and identify any environmental drivers potentially responsible.