A model that reconstructed the Mediterranean climate over 8,000 years suggests a combination of a long-term drying trend and fluctuations in the Atlantic Ocean and atmosphere. The researchers emphasize that drought was not necessarily the sole cause of the collapse, but it increased the pressure on water, agriculture and food supplies
About 3,200 years ago, many societies in the eastern Mediterranean were plunged into deep crisis. Urban centers were destroyed or abandoned, trade networks disintegrated, government systems weakened, and the Hittite Empire and the Harmonia-Mycenaean civilization collapsed. Prolonged drought has long been considered one of the factors that contributed to the upheaval, but the climatic mechanisms that created such harsh conditions were unclear.
A new study by researchers at Stockholm University suggests that this was not a single climate event. According to the study, published in the journal Science Advances, the most extreme droughts were created when several climate cycles, operating on different timescales, connected and amplified each other's influence.
“Rather than the drought being caused by a single climate event, we found that the most extreme dry periods occurred when natural climate cycles operating on different timescales occurred simultaneously,” says Katherine Power, a doctoral student in the Department of Physical Geography at Stockholm University and the study’s first author. “This helps explain why the drought associated with the Late Bronze Age collapse was so severe.”
Reconstruction of 8,000 years of climate
Power and Professor Qiong Zhang, an expert in ancient climate modeling at Stockholm University, used an advanced climate model to reconstruct the changes that have occurred in the Mediterranean region over the past 8,000 years.
The results initially indicated a gradual drying trend that lasted thousands of years. According to the researchers, this trend was due to slow changes in the Earth's orbit, which affected the dispersion of solar radiation and atmospheric systems. The weakening of the monsoons and changes in atmospheric circulation reduced the supply of moisture from Africa and the amount of precipitation in the eastern Mediterranean.
But the long-term drying trend was not the only factor. On top of it, shorter-term fluctuations in the Atlantic Ocean and atmosphere acted. When these fluctuations acted in a drier direction and connected to the long-term trend, they created much more severe forms than the gradual drying alone would have caused.
According to Power, “the convergence of these processes pushed the Eastern Mediterranean beyond a critical hydro-climatic threshold, reducing water availability and increasing pressure on agriculture and food security in already vulnerable societies.”
Climate is not the sole explanation for the collapse of civilizations
The study does not state that drought alone brought down Bronze Age cultures. Social collapses are usually the result of a combination of factors, including conflict, migration, rebellion, disruption of trade, and political and economic weakness. The new findings provide a possible explanation for the strength of the environmental stress that acted in parallel with these factors.
Previous evidence collected in the region, including pollen grains from the Kinneret sediments and changes in the level of the Dead Sea, already pointed to a period of severe drought between the mid-13th century and the early 11th century BCE. The new study adds to the picture the broader mechanism: a slow drying trend, to which were added shorter oceanic and atmospheric fluctuations.
Societies that relied on rain-sensitive agriculture, limited water supplies, and long trade networks could struggle to cope with a series of droughts. Falling crops could exacerbate food shortages, encourage migration, and weaken the ability of kingdoms to maintain armies, cities, and government structures.
A warning also for the future of the Mediterranean Sea
The findings also have implications for understanding contemporary risks. The Mediterranean region is considered a particularly sensitive hotspot for climate change, and is expected to warm and dry up over the course of this century.
“Our results suggest that the risk of future drought may depend not only on long-term warming caused by human activity, but also on how natural variability in the Atlantic Ocean interacts with this background trend,” explains Power.
This does not attribute the current warming to natural cycles. The study highlights another point: Natural fluctuations can combine with human-induced warming to create more extreme droughts. As occurred during the Bronze Age, exceeding a critical threshold of water availability could turn gradual climate change into a rapid crisis for agriculture and society.
Questions and Answers
What happened in the eastern Mediterranean about 3,200 years ago? Several Late Bronze Age cultures and polities collapsed or were greatly weakened, including the Hittite Empire and the harmonious centers of Mycenaean culture.
Was the drought the only reason for the collapse? No. The study examines climatic conditions, but the collapse is also linked to wars, migration, trade disruptions, social tensions, and the weakness of governance systems.
What created the extreme drought? According to the model, a long-term drying trend was coupled with shorter-term fluctuations in the Atlantic Ocean and atmosphere. When several drying processes occurred together, their effects were amplified.
What can we learn from this about the future? Human-induced warming could combine with natural climate fluctuations. Such a combination could temporarily exacerbate drought in the Mediterranean region beyond the average trend.
For the scientific article: Opening the scientific article
More on the subject on the science website
- Tel Aviv University researchers: Middle Eastern empires collapsed because of a climate crisis
- The Dead Sea is low, another culture is disappearing
- The Indian Ocean may provide advance warning of prolonged drought periods in Israel
- Bronze and Iron Age farmers invested in irrigation to preserve grapevine crops
- The Fall of Troy and Environmental Pressure: Lessons for Today
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According to climate cycles, if it weren't for human intervention, we would have been in a cold period.
And all this happened before there were environmental pollutions of the twentieth century.
More proof of climate cycles that have nothing to do with air pollution.
At the same time, it is desirable and necessary to maintain a clean environment for the sake of our quality of life.