The Top 5 Ancient Civilizations Destroyed by Climate Change

In the Proceedings of the National Academy of Sciences, researchers recently published evidence that climate change caused the collapse of the ancient Harappan civilization.   In honor of this discover, I have compiled a Top 5 list of ancient civilizations destroyed by climate change.  In each of these cases, climate change led to an agricultural collapse and was often associated with drought.

1. The Harappan civilization

• Time Period: 3000 B.C. – 1000 B.C.
• Population at Height: ~ 100,000
• Location: India, Pakistan, Nepal, and Bangladesh
• Accomplishments: Writing, Arts, Plumbing, Shipping
• The End: This ancient civilization was highly dependent on the Saraswati river to support its agriculture.  A decline in rainfall sometime around 1000 B.C. caused the surface water resources to plummet.  The people were forced to migrate away from their cities.  The Harappans civilization was both created and destroyed by the same climate trend – a gradual drying out of the region.  At first, this trend made the region habitable, ending the sever floods that would have devastated farms.  But eventually, this decline resulted in an agricultural collapse.

2. Mayans

• Time Period: 250 – 900 A.D.
• Population at Height: 20 million
• Location: Mexico and Central America
• Accomplishments: Astronomy, Literature, Calendars, Architecture
• The End: The Mayan population grew to such an extent that it was using all available water resources. It lacked the capacity to survive a severe drought, which is exactly what it faced, sometime around 800-950 A.D. The drought may have led to other problems, such as civil unrest and disease, and together these events destroyed the civilization.  The Mayan people probably contributed to the climate change by clear-cutting the forest.  As many as 95% of them died following the crisis.

3. Egyptian Old Kingdom

• Time Period: 2649–2150 B.C.
• Population at Height: 2 million
• Location: Upper Egypt
• Accomplishments: Art, Architecture, Mythology
• The End:  Right before the collapse of Egypt’s Old Kingdom, King Pepy II ruled for 90 years.  In the 20 years after his death, 18 different rulers briefly held the title before the institution fell apart.  The cause of the collapse remains mysterious, but Egyptologist Dr. Fekri Hassan has argued that the disintegration of the society was caused by reduced flows in the Nile River.  This drought lasted several years.  A study of dust deposits from the Kajemarum Oasis in Nigeria revealed a short-lived cold-climate event that corresponds to this period.

4. Ancient Rome

• Time Period: 27 B.C – 500 A.D.
• Population at Height: 60 Million
• Location: Mediterranean region
• Accomplishments: Advanced Construction Techniques, Philosophy, Mathematics, Arts, Literature
• The End: By analyzing tree rings, researchers recently discovered that the fall of Rome corresponds to a period of climate shift from 250 to 550 A.D.  The tree rings indicate that trees were stressed during that time-frame, suggesting an unusually cold or dry periods.  These poor growing conditions probably also impacted agriculture.

5. Agricultural Chinese Dynasties

• Time Period: 200 B.C – 1643 A.D.
• Population at Height: 60 million
• Location: Southern China
• Accomplishments: Arts, Architectural, Mathematics, Astronomy, Literature
• The End: Dr. Zhibin Zhang has correlated the collapse of several agricultural dynasties with cool temperature periods.  These include the Han (206BC-AD220), Tang (681-906), Song (960-1279) and Ming (1368-1643) dynasties.  Dr. Zhang has postulated that these climate fluctuations interrupted the agricultural food supply, leading to social upheaval and rebellion.

Conclusion

A sudden decline in water resources is the most significant factor contributing to the collapse of civilizations.  Social unrest and political upheaval often disguise the true destabilizing factor: an inability to produce enough food.