In stone mines near Fairbanks, Alaska, scientists are now searching for something and it is not metal.
They’re searching through layers of historical sediment for hints about the way in which the area’s climate shifted during intervals of global warming. The proof is in the dirt itself, which contains chemical compounds that could show information as to whether the region became weatherier or drier as the fever had changed in ancient times.
The project can help researchers and policymakers understand how Alaska might respond in the years to come, as the world warms up. Given that the state is feeling the effects of climate change, this is an urgent topic of study.
According to the 2014 National Climate Assessment, Alaska has warmed up much quicker than the rest of the US in recent centuries. The research found that glaciers were melting, the hazards of wildfires were increasing, and adjacent fisheries were vulnerable to modifications in ocean temperatures.
“Alaska is currently experiencing rapid climate change,” says Elizabeth Thomas, PhD, a geologist at the University of Buffalo, who leads the analysis. “By analyzing the way weather in the region has acted in the past, we have been better able to predict the future.”
“Another reason why the research is intriguing is that high-latitude regions are a bellwether to climate change. As they heat up, glaciers and ice sheets melt, and this affects people around the globe because it can trigger sea-level rises,” says Thomas, Assistant Professor of Geology at UB College of Arts and Sciences.
Study of human-made canyon walls
The region Thomas is now working in is just south-east.
She was with a group this summer, including Britta Jensen, Ph.D., Earth and Atmospheric Science Assistant Professor at Alberta University; Kayla Hollister, M.Sc. student in Geology at UB; with Nathan Pollard-Yopek, a master’s student in Earth Sciences and Atmosphere at the University of Alberta.
The mines that collect samples are the pleasure mines that once flowed into the creeks, leaving gravel deposits, including gold, behind. Now, those gravels are buried under hundreds of feet of windblown silt — deposits called loess — which arise in mountains that were nearby when stone crush into dust.
Miners must carve deep trenches to get to the precious metal. The walls of the canyons work as a listing of moment. They hold layer upon layer of loess in Earth tones that are exquisite — yellows that are sandy, delicate grays , variants of ochre — which scientists could date and examine to find out about the area’s climate history.
“Miners and scientists have been collaborating for a long time,” says Thomas. “The miners dig these giant mounds of silt, which means we do not have to act ourselves, they were happy to welcome us in. For them, the sediment is just something they move constantly, so when we have asked could look at the walls of these mines, they would say enthusiastically: “You take care of our land?” ”
Interpreting chemical clues
The sediments in the mines contain all sorts of interesting relics, such as the remains of old trees and the large bones of long-dead mammoths (Hollister devoured one).
Nevertheless, it is the dirt that interests the researchers.
In the temperate mountains, weather patterns brought about by changes in Earth’s orbit have caused glacial growth and contraction over the past few million years.
When glaciers were large, loess was deposited nearby at layers. However, if the weather prevailed, forests climbed atop the loess. These areas are coated by dust in times that were cooler, and so on and so on. Now, what remains of these forests are bits of soil layers of trees, and land that is rich, dark — all found at the walls of the mines.
Throughout the summer visit to Alaska, the study team measured sections of sediment and disposed of them.
Jensen’s laboratory will date samples of volcanic ash buried in the loess, which will give an idea of the age of the sediment segments. Meanwhile, his team and Thomas will examine the compounds present in the sediments to learn more about the ancient climate of the region.
One material that the researchers will explore: Compounds called glycerol dialkyl glycerol tetraethers (GDGTs), which can be inserted in the loess. GDGTs could be used to reconstruct temperature trends. In a separate analysis, the scientists will examine the remnants of leaf waxes. The chemical make-up of those chemicals can shed light on the region moisture — affected by rain and humidity levels — fluctuate over the time.
The research will pay for distinct warm intervals that have occurred during the Pleistocene, which began roughly 2.6 million years back and ended about 12,000 years back.