It's a sad Christmas for the world's reindeer—the antlered Arctic grazers associated with all things Santa Claus. Their numbers have fallen by more than half in the past 20 years, and climate change is likely to blame.

The latest numbers come from the National Oceanic and Atmospheric Administration's 2018 Arctic Report Card, which listed the increasing impacts of global warming on the earth's northernmost region, as EcoWatch has already reported. But the loss of Rangifer tarandus—called caribou in North America and Greenland and reindeer in Siberia and Europe—is of note because it threatens to further throw Arctic ecosystems and cultures out of whack. Reindeer are important prey for wolves and biting flies, and a key source of food and clothing for indigenous groups.