Did climate fluctuation save Europe?

An unusually cold winter was responsible for the sudden withdrawal of the Mongolian army from Hungary in 1242, a new study suggests.

By studying tree-ring formations, historical records and palaeoclimatological data, a team of researchers have suggested that a small change in climate was partly responsible for the mighty Mongolian empire suddenly retreating from eastern Europe.

It has long remained a mystery as to why the Mongolian army, led by the descendants of Chinggis (Genghis) Khan, decided to abandon its invasion of modern day Hungary and return to Russia. Until this point, the Mongols had faced little resistance and were driving into Europe as part of a territorial expansion.

According to results obtained from a multi-faceted study, the winter of 1242 was slightly colder, only a couple of degrees, than preceding years. This slight temperature variation lead to widespread environmental changes.

Tree ring data from the region where the Mongols halted their advance were found to have a more severe period of stunted growth, an indicator of a colder winter.

This cooler climate would have frozen lakes and rivers, helping the Mongols traverse the landscape and make their push. However, when this winter came to an end, the ground was left unusually wet and muddy.

This is believed to have hindered crop growth and that the failing crop group caused starvation amongst both the soldiers and their horses.

On top of this the increased moisture caused by winter melts made the ground marshier, hampering the movement of troops and supplies.

This culminated in a weakened force, forcing military leaders to call for a retreat to drier pastures.

While the study does not provide conclusive evidence that climate change was the only reason for this historical event, it is the first time that a short term climate fluctuation has been implicated in forcing the Mongols to abandon their advance.

The study was published in Nature.