Genghis Khan, one of the most ruthless rulers in history, is being hilariously recast as a hero of the green movement by historical research. In a terrific case of accidental consequences, scholarship now contends that Khan and his brutal Mongol invasion in the 13th and 14 centuries probably cooled the planet. How? Because he killed so many people–an estimated 40 million–that forests were able to regrow from cultivated fields that were returned to their natural state.
No scholar at Carnegie Institution’s Department of Global Ecology has found any archived notes indicating Khan’s murderous spree was triggered by his concern about the environment. But the research does put in perspective the long history of human activity affecting the environment. “It’s a common misconception that the human impact on climate began with the large-scale burning of coal and oil in the industrial era,” said Julia Pongratz, who headed the Carnegie Institution research project.