Nobody knows for sure. Maybe a Syria-style (but ten times stronger) migration from Russia westwards? It is assumed that Syrian crisis started happening when it

Nobody knows for sure. Maybe a Syria-style (but ten times stronger) migration from Russia westwards? It is assumed that Syrian crisis started happening when its Oil exports dipped in red, as in existing Syrian economy would consume more Oil than they were capable to extract. Worsening climate did not help of course.