Sergey Aphanasievich Zimov (Russian: Сергей Афанасьевич Зимов; born 18 July 1955) is a Russian geophysicist who specialises in arctic and subarctic ecology. He is the Director of Northeast Scientific Station (a research institute of the Russian Academy of Sciences), a senior research fellow of the Pacific Institute for Geography (an institute within the Far East Division of the Russian Academy of Sciences (FED RAS)), and one of the founders of Pleistocene Park (a 160 km2 wildlife preserve and a research substation of the Northeast Scientific Station). He is best known for his work in advocating the theory that human overhunting of large herbivores during the Pleistocene caused Siberia's grassland-steppe ecosystem to disappear and for raising awareness as to the important roles permafrost and thermokarst lakes play in the global carbon cycle. According to a colleague, Sergey Zimov is the most cited Russian earth scientist. Source: Wikipedia (en)