California State University Long Beach 

 Climate change and civilizations

•  Holocene climatic variation recorded in Greenland ice cores & North Atlantic sediment
• Continuation of Dansgaard-Oeschger cycles but at lower amplitude
•  Approximately 2500-2600 year cycles
•  Warm and wet, or
•  Cold, dry, and windy
•  8800-7800, 6100-5000, ~3950, 3100-2400, & 600-150 yrs b.p.

   Origin of Noah’s flood and Gilgamesh legends?

• Ryan and Pittman’s new story
•  Early in the Holocene
•  Black Sea was smaller, fresher lake
•  Cut off from Mediterranean by the Bosphorus Straits
•  Agriculture had developed on flat, fertile ground
•  Approximately 7,500 years ago (5500 B.C.)
•  Warmest interval of the Holocene
•  Raising sea level rushed through the Bosphorus Straits
•  Flooded flat, fertile ground with salt water
•  Farming and root languages spread through Europe and  Middle East

Mesopotamia

•  2000-2200 B.C. (~4000 years ago)
•  Destruction/abandonment of Akkadian cities and civilization
•  Possibly also Greece, India, Egypt, etc. simultaneously collapsed
•  Climatic cooling, increased aridity, and windiness
•  Expansion of desert areas (Sahara, etc.)

 Classic Mayan civilization collapsed (Yucatan, Mexico)

•  800 A.D. (~1200 years ago)
•  200 years of increased climatic dryness (relative drought)
•  Changes in relative evaporation/precipitation
•  Shown by oxygen isotope values of shells in lake core sediments
•  Gastropods
•  Ostracods
•  Driest interval of the entire middle to late Holocene
•  Past 7,000 years
•  Similar climatic record throughout the Mesoamerica/Caribbean region
•  Compounded social and resource problems

 

---

Little Ice Age

•  1400 A.D. to 1800’s A.D.
•  Last cold stage in Holocene

Back to the Beach!

Or click  here to return to the Department of Geological Sciences home page