In Siberia, a plan is under way to repopulate the grasslands with ancient grazers, including, in the near future, genetically engineered woolly mammoths. Much more than an experiment in biodiversity, this is a radical scheme to slow one of the most dangerous contributors to global warming—before it’s too late. Read text version here: https://www.theatlantic.com/magazine/archive/2017/04/pleistocene-park/517779/