The difference is immediately noticeable. The tundra of the far north in eastern Siberia makes a barren impression with its yellowish-brown hues. Not far away, musk ox, horses, elk, bison, reindeer and even camels graze on lush green grassland. "With this green savannah, a landscape typical of the Ice Age returns to the far north, where mammoths and other large mammals lived thousands of years ago," says Martin Heimann from the Max Planck Institute for Biogeochemistry in Jena. "On top of that, this mammoth steppe protects the permafrost underneath from thawing in the face of climate change and thus turns out to be a relatively inexpensive climate protection measure."
Sergej Zimov and his son Nikita from the Russian Academy of Sciences have been bringing back this landscape on the Kolyma River, which disappeared with the Ice Age and the mammoths, in a 160 square kilometer Pleistocene park since 1988. Heimann, who has been working with the two of them for 20 years, examines the respective influences of today's tundra and the former mammoth steppe on permafrost and the climate.
The savannah, lush green in summer and icy cold in winter, on which as many large mammals grazed in the Ice Age as in the Serengeti of East Africa today, has been one of the most extensive landscapes on earth for 2.6 million years.
In front of the mighty ice sheets over northern Europe and America, the mammoth steppe stretched from the Iberian Peninsula to North America almost around the globe.
The end of the Pleistocene was approaching when people with weapons began to appear more and more frequently more than 10,000 years ago.
They hunted the large mammals until some species like the mammoth became extinct and others like the wild horses were massively decimated.
Lush green in summer, icy cold in winter
The disappearance of these animals changed the landscape and the climate tremendously. In addition to herbs and grass, mammoths and bison also ate germinating trees and bushes, knocked down trees or broke branches to get at the green leaves. "The mighty bison also like to rub against the trunks of large trees and can peel off the bark over time," says Heimann. This can also cause large trees to die. In areas where buffalo are found, woody plants should become rarer, while grasses, herbs and perennials appear more and more.
The always hungry mammals eat a considerable part of the green. But they also leave behind plenty of excrement, and the nutrients they contain fertilize the mammoth steppes and thus accelerate the growth of vegetation. This eternal cycle made the mammoth steppes of the Ice Age an extremely productive ecosystem that could feed huge herds. Marc Macias-Fauria from the University of Oxford and his colleagues calculated on the basis of fossils that 15 reindeer, seven or eight wild horses, five bison and one mammoth lived on an area of just one kilometer long and just as wide of the mammoth steppe on the Kolyma River the end. Then there were woolly rhinos, moose and predators such as wolves and cave lions.
When the hunters and gatherers of the Stone Age decimated the huge herds in the savannahs of the north at the end of the Ice Age and exterminated species such as the mammoth and woolly rhinoceros, this ecosystem collapsed. After 2.6 million years there was nothing left of the lush mammoth steppe. In the far north it was replaced by a barren tundra, on which instead of many grasses and herbs abundant mosses, lichens and dwarf shrubs grow. From the herds of animals only reindeer and elk remained, today not even one percent of the animals that once lived in the mammoth steppe graze on the same area.
This change affects the climate. The far north is still covered by a thick blanket of snow for eight months or more. Only the mammoth steppe of the Ice Age was dazzling white and therefore almost completely radiated the heat of the sun back into the sky. “Today, on the other hand, the dwarf shrubs protrude from the snow, especially in autumn and spring, and their dark color absorbs much more solar energy than the snow,” says Heimann. The tundra is getting warmer - and climate change is accelerating this development.