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 series of worldwide record cold winters and crop disruption, which geologists in 2008 linked to the 1600 volcanic eruption of Huaynaputina in Peru.