The Russian famine of 1601–1603, Russia's worst famine in terms of proportional effect on the population, killed perhaps two million people: about 30% of the Russian people. The famine compounded the Time of Troubles (1598–1613), when the Tsardom of Russia was unsettled politically and later invaded (1605–1618) by the Polish–Lithuanian Commonwealth. The many deaths contributed to social disruption and helped bring about the downfall of Tsar Boris Godunov (r. 1598–1605), who had been elected tsar in 1598. The famine resulted from a volcanic winter, a series of worldwide record cold winters and crop disruption, which geologists in 2008 linked to the 1600 volcanic eruption of Huaynaputina in Peru.