Researchers from the University of Wisconsin-Madison have found deep underground soils to be rich in carbon content.
The researchers said that soil erosion, deforestation, mining, and farming, can disturb and uncover these soil formations, according to a press release issued by the university.
As a result, carbon that had been sealed away for "thousands of years" in semi-arid and arid environments is more likely to be reintroduced to the environments that can contribute to global climate change.
"There is a lot of carbon at depths where nobody is measuring," said Erika Marin-Spiotta, an assistant professor of geography and the lead author of the study, in the release. "It was assumed that there was little carbon in deeper soils. Most studies are done in only the top 30 centimeters. Our study is showing that we are potentially grossly underestimating carbon in soils."
For their study, the researchers studied Brady soil, which formed between 13,500 and 15,000 years ago in Kansas, Nebraska, and other locations in the Great Plains and around the world.
The soil can be found six-and-a-half meters below the surface, buried by accumulation of windblown dust known as loess after glaciers in North America started to retreat approximately 10,000 years ago.
Once the glaciers began to recede, the area where the soil formed went through a radical change, including wildfire and vegetation, which contributed to carbon sequestration.
Marin-Spiotta said that most of the soil is black carbon and was the result of wildfires, according to the release.
The researchers used new analytical methods, like isotopic and spectroscopic analyses, to study the soil and its chemistry. The team said that rapid burial of Brady soil stopped them from undergoing biological processes that would normally dissolve carbon in the soil.
The Brady soil can be considered as a time capsule of a past environment. It allows environmentalists a chance to see how the environment endured various climate shifts, according to the release.
"The world was getting warmer during the time the Brady soil formed," said UW-Madison geography Professor and study co-author Joseph Mason, according to the release. "Warm-season prairie grasses were increasing and their expansion on the landscape was almost certainly related to rising temperatures."
The study was published in the journal Nature Geoscience.