Besides powering Santa’s sleigh, reindeer also power the Arctic ecosystem. Massive herds of deer roam the tundra, shaping the vegetation of the region and providing a major food source. But like Arctic sea ice, reindeer—also called caribou—are in retreat. Over the past two decades, the abundance of caribou has plummeted an astonishing 56 percent, from about 4.7 million animals to 2.1 million.
While that number is dramatic, it isn’t unprecedented, according to Brian Resnick at Vox. Resnick reports that historically, caribou go through natural boom and bust cycles, which means herds will grow to number in the hundreds of thousands then steeply decline to the tens of thousands, only to bounce back once more. But in the latest report, part of NOAA’s particularly grim 2018 Arctic Report Card, researchers are beginning to wonder if the populations have fallen too far to recover.
“The fact that these herds are declining shouldn’t be a shock — they do it all the time,” ecologist Don Russell, who authored the caribou section of the report, tells Resnick. “But they’re at such low levels, you start to be concerned. ... If we return in 10 years and [their numbers] have gone down further, that would be unprecedented… [The question now is] are their numbers so low they can’t recover?”
According to a NOAA press release, only one of the 23 major caribou herds in the Arctic, the Porcupine herd in Alaska, is near its historic population high of around 200,000 animals. The remaining three herds in Alaska have dropped by 57 percent since reaching peak numbers between 2003 and 2010. In Canada, nine herds of caribou have declined so sharply they have been listed as threatened and two herds of migratory caribou in the eastern part of the country have been given endangered status. In total, five of the 22 herds of caribou in the Alaska-Canada region have dropped nearly 90 percent, and scientists are concerned they will never rebuild. In Russia, 18 out of 19 herds are showing major signs of decline.
The cause of the decline is likely secondary effects from climate change. Howard Epstein, an environmental scientist from the University of Virginia who also worked on the report, tells Victoria Gill at the BBC that warming in the region has many impacts.
“We see increased drought in some areas due to climate warming, and the warming itself leads to a change of vegetation,” he says, with other species replacing the ground-level lichen the caribou like to graze on. “Warming means other, taller vegetation is growing and the lichen are being out-competed.”
Then, there are the bugs. Warmer days mean more insects plaguing the animals, who use more energy swatting and shrugging off biting insects or trying to find less buggy pastures. An increase in rain can be a problem, too; wet weather leaves a frozen layer on top of the snow behind, making it harder for the animals to break through the ice to nosh on lichen.
It’s not just the reindeer that are suffering. According to the report, since 2014 the warming in the Arctic has been dramatic and “is unlike any other period on record.” Besides seeing caribou and the ecosystems they support disappear or diminish, the report indicates the air temperature in the region is the highest it’s ever been, warming Arctic waters are resulting in harmful algae blooms, Arctic sea ice is thinner and less widespread than ever before and microplastics are beginning to infest Arctic marine ecosystems.
Those are problems that even Rudolph couldn't guide us through—even if his herd was healthy and stable.