Ancient Secrets Unveiled: 5,900-Year-Old Trees Emerge from Wyoming’s Thawing Ice

A melting ice patch in the Rocky Mountains has uncovered the remains of trees that are up to 5,900 years old, which could provide valuable insights into climatic conditions of the past, according to fresh research.

Researchers found over 30 deceased whitebark pine trees (Pinus albicaulis) that had been buried in ice for thousands of years, as reported in a new publication released late last month in Proceedings of the National Academy of Sciences.

The concealed cluster of trees was located on the Beartooth Plateau in northwest Wyoming, which is part of the Greater Yellowstone Ecosystem. The whitebark pines were found lying flat but remained in remarkably good condition, indicating they were quickly encased in ice.

The trees were uncovered when the ice patch started to melt due to increasing temperatures attributed to human-induced climate change, reports New Scientist’s Taylor Mitchell Brown. In the vicinity, retreating ice patches have also exposed remnants of ancient wooden hunting tools, including one that dates back to over 10,000 years ago.

“The plateau appears to have been an ideal location for ice patches to form and remain for millennia, capturing critical data on historical climate, human interaction, and ecological changes,” states study lead author Greg Pederson, a paleoclimatologist at the United States Geological Survey, in a statement.

The trees are situated 10,140 feet above sea level, roughly 590 feet higher than the present tree line in that area. (The tree line, also referred to as timberline, signifies the boundary of a high-altitude habitat capable of supporting trees. Above this invisible line, the conditions become too harsh for tree growth.) This indicates that the region’s climate was likely warmer in earlier times.

Researchers used tree ring analysis and radiocarbon dating methods to ascertain that these trees thrived between 5,950 and 5,440 years ago. Subsequently, they examined data from Arctic ice core samples to gain insights into the climate conditions during that era, known as the mid-Holocene.

The trees lived during a time of declining temperatures, which have been associated with persistent volcanic eruptions. As volcanoes in the Northern Hemisphere erupted, they released vast quantities of ash into the atmosphere, which blocked sunlight from reaching the surface, causing temperature drops.

Eventually, approximately 5,100 years ago, it became so frigid that the trees at such a high elevation could no longer survive. The cold also prompted the nearby ice patch to grow and cover the whitebark pines.

The trees are described as a significant ‘time capsule’ that provides insights not only about these mountain forests 6,000 years ago but also about the climatic conditions that made their existence possible,” states Kevin Anchukaitis, a paleoclimatologist at the University of Arizona who wasn’t involved in the study, to New Scientist.

By uncovering more about the historical climate of the region, scientists believe they can make more precise predictions about the future. If global temperatures continue to increase, for instance, they predict that tree growth will shift to higher elevations, assuming adequate moisture is available.

“Records from one year to the next, as well as those spanning decades and even centuries, are incredibly valuable,” explains study co-author Craig Lee, an environmental archaeology researcher at Montana State University, to the Billings Gazette’s Brett French. “They provide vital comparative data that helps us frame our detailed observations of the current climate we experience today.”

Currently, the whitebark pine is categorized as “threatened” under the Endangered Species Act. These trees are challenged by numerous stress factors, including increasing temperatures, drought, and wildfires. Furthermore, they are contending with a pest known as the mountain pine beetle and a harmful invasive fungus referred to as white pine blister rust.

Robust whitebark pines can endure for centuries—and occasionally last up to 1,000 years. They thrive at high altitudes across the western United States and Canada, supplying food for red squirrels, grizzly bears, Clark’s nutcrackers, and various other species. They also play a crucial role in their elevated ecosystems by offering shade that helps maintain snow in a cold and stable state.