The Medieval Warming, which was eventually followed by a Solar Maunder Minimum and Little Ice Age, is well known. And the Mongols weren’t the only band of murderous (in the best sense) barbarians who expanded their reach during that centuries long age. There are plenty of Irish folks with “son” at the ends of their family names whose ancestral roots go back to some formerly frozen hovels on the coasts of Norway and Sweden. Dublin itself was a Viking outpost.
correlation versus causation
Given any two time series X (for example, as mean global temperature) and Y (extent of the Mongolian Empire), there will almost certainly be a correlation if they are both slow-moving and we only look at a relatively short period of time.
Let’s say global temperature has a phase that is a few hundred years long, and we look at the expansion of the Mongolian Empire over a period of one hundred years. Unless that one hundred period straddles a turning point in global temperature, the expansion of the Mongolian Empire will appear to be correlated with the global temperature, even if there is no causation.
WORD FOR THE DAY: Ergodic.
Really, there is no excuse for climate science to be so ignorant of statistics.
I am constantly amazed at the ability of scientists to discover very old ideas.
I've read in several histories from the 18th and 19th centuries, including Gibbon, that a few decades of good weather and rain on the steppes would lead to expansion of herds and of the human population.
Then the weather goes to drought, the tribes go to war with each other, consolidate into empires and eventually come boiling out of the steppes into Europe, the Middle East, India or China.
Happened dozens of times, with the Mongols being only the most recent and most dramatic of these cycles.
This was of course based on the fact that, when properly used, the mounted archer with the recurve bow was the most effective weapon system on the planet for several thousand years. These cycles would still be going on if technology hadn't created even more effective weapon systems.
Huh.
And here my ignernt unedumakated self always thought that the Mongol Empire was created because some yahoos assassinated a dude’s dad and got him really really pissed off.
And the really really pissed off dude managed to not only get even, eventually, but also managed to organize some other dudes who were really really pissed off at the Chinese for constantly kicking dirt in their faces.
Never knew it was all just global warming.