The woolly mammoths of Siberia

Twelve thousand years ago, northern Siberia was home to woolly mammoths and other big, grazing mammals. Back then, the landscape was not moss-dominated tundra as it is today but grassland. Sergey Zimov, a Russian ecologist and director of the Northeast Science Station in Chersky, believes that this was no coincidence; the numerous herbivores maintained the grassland by breaking up the soil and fertilizing it with their manure. Once they disappeared, moss took over and transformed the grassy steppes into less productive tundra. In recent years, Zimov has tried to turn back time on the tundra by bringing European bison, musk ox, Yakutian horses, and other big mammals to a region of Siberia he calls Pleistocene Park. His theory is that by filling the vast, Russian Arctic with grass-eating animals, we can slow global warming. Today, climate change is being felt most sharply in the Arctic, where temperatures are warming faster than anywhere else on the planet. Zimov states that his herbivores will keep wild grass short and healthy, causing it to send up fresh shoots through the summer and fall. In winter, the animals will trample and flatten the snow that otherwise would insulate the ground from the cold air. That helps prevent the permafrost from thawing and releasing powerful greenhouse gases. Grass also reflects more sunlight than forests, a further impediment to global warming. Climate scientists and environmentalists are watching Zimov’s Pleistocene Park project closely. Skeptics say, however, that it will take millions of animals to change the landscape of Siberia and effectively seal the permafrost. But Zimov says that left alone, big grazers such as bison, caribou, and musk ox multiply quickly. He believes the next step — with the help of de-extinction scientists — may be to bring in the woolly mammoths.