New research suggests that in addition to being one of history's cruelest conquerors, Genghis Khan may have been the greenest. It is estimated that the Mongol leader's invasions unintentionally scrubbed almost 700 million tons of carbon from the atmosphere. From the article: "Over the course of the century and a half run of the Mongol Empire, about 22 percent of the world's total land area had been conquered and an estimated 40 million people were slaughtered by the horse-driven, bow-wielding hordes. Depopulation over such a large swathe of land meant that countless numbers of cultivated fields eventually returned to forests. In other words, one effect of Genghis Khan's unrelenting invasion was widespread reforestation, and the re-growth of those forests meant that more carbon could be absorbed from the atmosphere." I guess everyone has their good points.