Genghis Khan is known as one of the greatest conquerors of all time. Aside from a massive army of fierce horse-mounted warriors, the Mongol emperor may have also had a little help from the heavens.

Before Genghis Khan came along, the fierce tribes of the Mongol steppe were plagued with constant tribal warfare. However, the warlord was able to consolidate the horse-mounted nomads into one of the most effective fighting forces the world has ever seen. In an unstoppable wave of horses and warriors, the unified Mongol tribes were able to carve a path of destruction culminating into one of the largest empires in history.

While Genghis Khan's leadership skills and strategic acumen have withstood the test of time, a new study published in the Proceedings of the National Academy of Sciences (PNAS) shows that climate change may have played a key part in Mongol Empire's rise to power.

A team of scientists from Columbia University's Lamont-Doherty Earth Observatory and the West Virginia University have uncovered surprising evidence of a period of climate change that coincided with Genghis Khan's military exploits. By studying a cluster of stunted Siberian pine trees in Mongolia, the researchers were able to create a climate history dating back to a period of time when the Mongol tribes were involved in fierce infighting.

The ancient pine trees found in the Khangai Mountains were over 1,100 years old. In fact, some of the trees were still alive, having lived through the rise and fall of the Mongol Empire. By analyzing the tree rings on the trees, the researchers were able to determine that before the Mongol tribes were united, the entire region was under a harsh dry spell. This happened in the late 1100's, and the lack of resources caused by the draught may have fueled the constant conflict between Mongol tribes.

During long dry spells, tree's often exhibit stunted growth characterized by very thin tree rings. When rain and water is plentiful however, tree rings can be a lot thicker. The researchers found that the end of the drought coincided with Genghis Khan's empire building blitzkrieg. Analysis of the tree rings showed that a period of mild temperatures and heavy rainfall occurred between 1211 and 1225. This may have brought about a sudden increase in available resources for the Mongol horde.

"Before fossil fuels, grass and ingenuity were the fuels for the Mongols and the cultures around them, energy flows from the bottom of an ecosystem, up the ladder to human society," said Neil Pederson, a scientist specializing in tree-rings from Columbia University's Lamont-Doherty Earth Observatory. "Even today, many people in Mongolia live just like their ancestors did. But in the future, they may face serious conditions." Pederson is also the lead author of the study.

Richer grazing grounds nourished by heavy rainfall coupled with a mild climate suitable for raising livestock and horses were vital to the growth of the Mongol war machine. Considering that the average Mongol warrior at the time maintained around five horses, verdant grass lands may have indeed played a huge part in increasing the strength of Genghis Khan's fighting force.

"The transition from extreme drought to extreme moisture right then strongly suggests that climate played a role in human events," said Amy Hessl, an associate professor of geography from the West Virginia University and a co-author of the study. "It wasn't the only thing, but it must have created the ideal conditions for a charismatic leader to emerge out of the chaos, develop an army and concentrate power. Where it's arid, unusual moisture creates unusual plant productivity, and that translates into horsepower. Genghis was literally able to ride that wave." 

While the historical significance of the discovery may be invaluable to understanding the cultural, political and environmental factors involved in the rise of the Mongol Empire, the researchers' findings may also be useful in helping scientists gain a better understanding of how climate change can affect the world today.

"This last big drought is an example of what may happen in the future, not just in Mongolia but in a lot of inner Asia," said Pederson. "The heat is a double whammy-even if rainfall doesn't change, the landscape is going to get drier."

Mongolia has been experiencing a period of rapid climate change in recent decades. In as little as 40 years, temperatures in the region have risen by approximately 4.5°F.

In a sense, livestock have, up to now, served as the "fossil fuel" of Mongolia. Are there limits? "We're living in a pretty interesting time, when some of our own major sources of energy appear to be pretty tenuous. I think we can look to prior civilizations to see how they dealt with changes in energy availability. At any one time, there were winners, and there were losers," said Hessl. 

ⓒ 2021 All rights reserved. Do not reproduce without permission.