Scientists from the Desert Research Institute (DRI), Montana State University, and the U.S. Geological Survey have uncovered a 6,000-year-old forest preserved in an ice patch on the Beartooth Plateau. This research, led by Joe McConnell and Nathan Chellman of DRI, alongside others, provides insights into past climate conditions and potential future changes.
The study reveals that long-term shifts in Earth's orbit and volcanic activity caused global cooling at the end of the mid-Holocene warm period. This cooling led to Rocky Mountain forests retreating from higher elevations. The findings are expected to shed light on how forests might respond to current climate change.
"We’ve been trying to determine how the ice patch formed and why it has persisted and so preserved the buried forest for millennia," McConnell stated. Further results will be shared in upcoming publications.
Published in the journal Proceedings of the National Academy of Sciences, this paper describes how a mature whitebark pine forest once thrived at 10,000 feet elevation around 6,000 years ago when temperatures were similar to those of the mid-to-late 20th century. Cooling temperatures approximately 5,500 years ago caused by reduced summer solar radiation transformed these areas into alpine tundra.
David McWethy from MSU's Department of Earth Sciences highlighted that volcanic activity further cooled temperatures leading to quick encasement of forests in ice. "This is pretty dramatic evidence of ecosystem change due to temperature warming," he noted.
The discovery originated from work by Craig Lee who found a portion of an ancient tool dating back over 10,000 years in an ice patch on Beartooth Plateau. The research team was awarded funding through various grants including a $100,000 Camp Monaco Prize and support from the National Science Foundation for broader studies involving multiple institutions.
Greg Pederson emphasized that tree line shifts are influenced by growing season temperatures along with other factors like moisture and human disturbance. The research suggests that as climate warms, tree lines could rise but exact changes depend on precipitation levels.
Cathy Whitlock warned about implications such as decreased high-elevation snowpack affecting water supplies downstream while McWethy pointed out potential wildfire risks if forests establish in tundra regions.