The summer 1601 was wet, and the winter 1601–1602 was severe. The eruption led to the Russian famine of 1601–03 after crops failed during these years; it is considered to be the worst famine of Russian history and claimed about two million lives, a third of the country's population. The events initiated the time of social unrest known as the Time of Troubles, and the tzar Boris Godunov was overthrown in part owing to the social impacts of the famine. This social unrest eventually led to a change in the ruling dynasty and interventions from Sweden and Poland.