Researchers found more than 30 dead whitebark pines that had been sealed in ice for millennia, representing a bygone ecosystem that could tell scientists about
climate change.
Melting ice in the Rocky Mountains has led to the discovery of tree remains about 5,900 years old that may provide insight into past climate conditions, a new study says.
The fact that scientists have discovered the remains of whitebark pines or as they are also called whitebark pines (Pinus albicaulis) is stated in a new scientific paper published late last month in the journal "Proceedings of the National Academy of Sciences".
They were able to reach previously hidden trees on the Bear Tooth Plateau in northwestern Wyoming, which is part of the Greater Yellowstone Ecosystem. The white-trunked pines were lying flat, but preserved in good condition, indicating that they had been quickly bounded by ice.
The trees were discovered recently when the ice cover began melting due to higher temperatures associated with anthropogenic climate change, reports Taylor Mitchell Brown in New Scientist magazine. In the same area, melting ice sheets have unearthed fragments of wooden hunting weapons, including one that is more than 10,000 years old.
"The plateau appears to have been an ideal location for the formation of ice layers that have persisted for thousands of years, recording important information about past climate, human activity and environmental change," lead study author Greg Pederson, a paleoclimatologist with the U.S. Geological Survey, said in a statement.
The trees are located about 3 kilometers above sea level, which is about 180 meters above the modern tree limit in the region. This suggests that the climate in the region was once warmer than it is today.
The tree boundary (treeline) marks the extreme limit of the spread of upright trees, which is usually formed by scattered groups of trees; above this invisible mark, conditions are too harsh for growth.
In a study of the ancient trees, scientists using year-ring analysis and radiocarbon dating methods determined that the trees were between 5,950 and 5,440 years old. To further understand the climatic conditions of this period - known as the Middle Holocene - the researchers turned to data from Arctic ice cores.
It turned out that the trees were growing in an era when temperatures were declining significantly. This climatic decline was directly related to a series of regular volcanic eruptions, which had a significant impact on global climatic processes.
When volcanoes in the Northern Hemisphere erupted, they released so much debris into the air that it blocked sunlight from reaching the surface, resulting in lower temperatures. The connection between these phenomena makes it possible to reconstruct a picture of natural changes at that time, which contributes to a better understanding of the planet's history.
Eventually, about 5,100 years ago, it got so cold that trees at that altitude could no longer survive. The chilly weather also caused the nearby ice patch to expand and swallow up the white pines.
"These trees can be called a unique 'time capsule' that opens a window to the past, allowing us not only a glimpse into the life of mountain forests nearly six thousand years ago, but also an understanding of the climatic conditions that contributed to their existence," notes University of Arizona paleoclimatologist Kevin Anchukaitis, who was not involved in this study.
Photo: smithsonianmag.com
The researchers emphasize that studying the region's ancient climate gives them the ability to more accurately predict changes in the future. For example, if global warming continues to intensify, trees may begin to climb to higher altitudes, provided that moisture levels remain sufficient for their growth.
"Records from a year, but also from decades and even a century, are extremely important," says study co-author Craig Lee, an environmental archaeology scientist at Montana State University. "They provide comparative data to contextualize our more subtle observations of current climate."
Today, the whitebark pine is considered an endangered species under the law. These trees face several stressors, including rising temperatures, drought, and wildfires. They also struggle with a pest called mountain pine mealybug and a deadly invasive fungus, whitebark pine blister rust.
Healthy whitebark pines can live for hundreds of years and sometimes live to be 1,000 years old. They grow at high altitudes in the western United States and Canada, providing food for red squirrels, grizzly bears, Clark's nutcracker (Nucifraga columbiana), and many other creatures. They also play an important role in high elevation ecosystems as they provide shade that helps keep the cold and snow cover stable.