They could be a valuable asset in keeping the soil cooler, longer.
In polar regions like the far north of Finland, temperatures rise four times faster than elsewhere, and reindeer could be a big help in keeping the ground cooler, longer.
By trampling the forest, they prevent shrubs from growing and compact the snow.
According to Bruce Forbes of the Arctic Center at the University of Lapland, these animals help maintain permafrost, the ground frozen all year round, threatened by global warming.
The problem is that the reindeer lack food and the lichen that grows on the century-old trees is now a rare commodity due to deforestation.
The Finnish state extracts six million cubic meters of wood every year. Under pressure from reindeer herders, operators are trying to cut down every second tree, but the timber industry is vital for the country.
Finland is therefore torn between two traditions: logging and reindeer herding, which should be encouraged to slow global warming.