Ice melt on Wyoming’s Beartooth Plateau unveils nearly 6,000 year old whitebark pines

Laying eyes on whitebark pines (Pinus albicaulis) in the mountains of northern Wyoming and the Greater Yellowstone Ecosystem (GYE) is not really news. The above picture shows a grove of them growing strong on Mount Washburn within Yellowstone National Park itself, as the trees flourish in the sub-alpine climates of most every major mountain range in the mountain west of North America.

You can hike right up to see them, if you want.

Whitebarks are a hardy species, one that typically exists right at treeline in these rugged mountain climates. They can often live to be nearly a thousand years old, too, if pine beetle infestations don’t devastate them en masse. As of 2022, they’ve been listed as ‘threatened’ under the Endangered Species Act in part due to infestations of beetles and invasive fungal diseases, though the rapid change in climate has begun to wreak havoc on its existence, too.

While that’s a quick and dirty summary of what whitebark pines currently are in the GYE, a recent discovery of more than 30 dead ones raises far more eyebrows. As Sarah Kuta of Smithsonian Magazine noted on January 13th, that’s precisely what researchers came across in melting ice on the Beartooth Plateau just east of the National Park, with carbon dating suggesting the trees date back some 5,900 years.

We’ve long known that these trees existed back then, so their particular age is not the story here. What is, though, is that they’ve been entombed within this particular sheet of ice for nearly six millenia, and warming climate across the country has finally melted enough ice to spit them back out.

Even more interesting is that the trees were discovered at 10,140 feet above sea level, or ‘roughly 590 feet higher than the region’s current tree line.’

Treeline varies by mountain range, with elevation only a piece of the puzzle determining where vegetation stops due to the harshness of the climate. Prevailing winds, orientation towards the sun, average temperature, and precipitation also factor into that equation. The the relatively short Cascade Range in Oregon, Washington, and British Columbia, for instance, sports treeline at roughly 6,000 feet given the fierceness of the climate in the area, while treeline in much of Colorado extends all the way up to 11,500 feet.

What’s clear in this particular discovery in the Beartooths, however, is that treeline when these whitebarks were entombed in the snow and ice was clearly much, much higher than the roughly ~9,550 feet level where it exists today. They were discovered nearly 600 feet above current treeline, but the ice in which they’d been buried for nearly 6,000 years has also ridden gravity downward at a glacial pace over that time, so they almost certainly existed even higher.

That’s evidence of a pretty wild shift in climate in the region in a relatively short span. And as average temperatures in the region continue to rise (and the glaciers like this recede), odds are treeline will gradually begin to move back higher towards this mid-Holocene elevation (assuming the precipitation that they desperately need remains something of a constant).