Climate Change May Have Caused The Rise And Fall Of Several Civilizations

genghis khan

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The climate is a big topic in San Francisco this week at the American Geophysical Union’s fall meeting.One part of that effort is looking to the past to understand how changes in temperature and precipitation affected the rise and fall of civilizations.

This morning I met one of the researchers involved in an effort to determine any connections between the rise of the Mongol empire – which at one time controlled more contiguous land than any other in history – and climate factors.

Amy Hessl from West Virginia University, working with two other researchers, has developed what she stressed was a hypothesis that wet conditions in the 1200s allowed the Mongols, led by Chinggis Khan (usually known to Americans as Genghis Khan) to come to power. They need to do much more work to verify the idea, she said.

The researchers looked at tree ring data from pine and larch trees. The growth rings indicated that trees grew well in the 13th  century.

“Both species show that conditions were wet in the 1200s, when Chengiss Khan came to power,” said Hessl.

The way these conditions may have helped the Mongols are as follows, Hessl suggested. The Mongols were nomads, who relied heavily on livestock such as sheep or goats, and also on horses. When the grasslands were well-nourished by rains, so were those animals, which helped the Mongols with both their needs for transportation and for food.

This is just the beginning of the researchers’ effort to investigate this connection, Hessl said. “This is an intriguing idea.”

In addition to making further investigations of the regional climate during the expansion of the empire, future efforts will investigate previous empires that originated in the same area hundreds of years earlier.

This has garnered some previous media coverage, such as this interview with LiveScience.

There are many other researchers looking at how climate changes led to the rise or fall of other civilizations. Yesterday, at a press conference, two researchers described their research into ancient Middle Eastern and South Asian societies, and the effect of droughts they suffered.

Sebastian Breitbach of EPH Zurich discussed the climate and its potential impact on Harappan culture, which was active in modern-day India between about 5,000 and 3,500 years ago, as well as a Persian civilisation from the areas we now call Afghanistan and Pakistan. As it is today in those areas, water was scarce at that time. The societies had advanced irrigation systems, but in times of great drought, they might not have been sufficient.

Breitbach gathers climate data from caves, which can provide good information, but actually collecting the data is difficult, he said, because many of the places where he might go to collect samples are either protected, hard to reach or otherwise impractical.

At the same press conference Matthew Konfirst, from the Ohio State University,  discussed the disappearance of the Sumerian civilisation and their language. In the cradle of civilisation in the Middle East — about 4,000 years ago — there were two major language families, he said.

One eventually became Hebrew and Arabic and other familiar languages, whereas the other family, Sumerian, stopped evolving when that civilisation collapsed, a linguistic dead end. That collapse coincided with a drought that lasted hundreds of years, he said.

It’s been fascinating to learn about how scientists are beginning to find data to verify why different civilizations succeeded or collapsed.

Konfirst summed up these efforts near the end of the press conference: “Climate itself is a fabric that society builds itself upon… There are a number of factors that come together to form what we call history.”