気候変動：干ばつがヒッタイト帝国の崩壊につながった可能性

A major drought that occurred in central Anatolia between around 1198 and 1196 BC may have had a key role in the collapse of the Hittite Empire, a Nature paper reports. The findings suggest that extreme climate change can push populations beyond their adaptation limits and centuries-old resilience practices.

The Hittite Empire, based in semi-arid central Anatolia, was a great power of the ancient world for over five centuries before its collapse around 1200 BC. The Empire had long proven to be resilient against regular sociopolitical, economic and environmental challenges, such as threat of drought. A 300-year shift to a drier, cooler climate around this period has been associated with the collapse of several ancient civilizations in the East Mediterranean and Near East. However, the precise details of associations between climate change and events in human history are less clear.

To assess the effect of drought in the collapse of the Hittite Empire, Sturt Manning and colleagues created a high-resolution dryness record using stable isotope records and measurements from tree rings of contemporary juniper trees in central Anatolia. They identified an unusually severe continuous dry period that occurred between around 1198 and 1196 BC. The authors suggest that this severe drought led to long periods of food shortages; the land-locked territories of the core Hittite realm were reliant on regional grain production and animal farming, which are particularly vulnerable to drought. These shortages would have led to political, economic and social unrest, as well as disease outbreaks — and eventually may have precipitated the collapse of the Empire.

This major drought in Anatolia may demonstrate a vulnerability of human systems to unexpected and consecutive multiyear climate extremes. These extremes can overwhelm human coping mechanisms and may apply both in history and today in the face of current climate change, the authors suggest.