According to Illarionov, “one can with a high degree of certainty assert that the qualitative changes in the ethnic composition of the population of Crimea took place in the course of the seven or eight months preceded the last census,” that is, “between February 27 and October 14, 2014.”But “the main event of the beginning of the 21st century has become the demographic catastrophe which has affected ethnic Ukrainians in Crimea,” when over the last 15 years they have lost 40 percent of their total and seen their share of the total population of the peninsula fall from 24 to 15 percent.
“In this case,” Illarionov says, “the sharp decline in the number of Ukrainians in Crimea was called forth evidently both by the mass departure of Ukrainians from Crimea and the conscious change by some of them of their official ethnic self-identification.” And to appreciate just how large those two factors are, he suggests, one could compare the number of ethnic Ukrainians in fact with the number of ethnic Ukrainians who would have been in Crimea at the end of 2014 if the same rates of change from the previous inter-censal period had continued. If that had been the case, there would have been 524,000 ethnic Ukrainians in Crimea, not the 180,000 fewer that the Russian census takers recorded in October 2014. That difference, he concludes, is a useful and appalling measure of “the cost of the Putin adventure for the Ukrainians of Crimea.”“The reduction of the population of any ethnic group of such a size over such a short period of time typically is caused by political events of an extraordinary character,” he points out, “by wars, famine, deportation, mass emigration or genocide. With the exception of periods of the civil war and World War II, such rates of reduction in the numbers of the population of this or that demographic as were seen in Crimea in 2014 were not seen in the last century.”

