As global warming thaws the frozen soils of the Arctic, more stored-up carbon could potentially be released into the atmosphere than previously thought, a new study suggests. Much of the frigid Arctic's soil is permafrost, or permanently frozen ground. Seasonal freeze-thaw cycles can mix up the soil layers, a process called cryoturbation, forcing organic (carbon-based) material into the subsurface layers and storing it in the permafrost. With Arctic temperatures projected to rise up to 10.8 degrees Fahrenheit (6 degrees Celsius) over the next 100 years, there is concern that this carbon will be released as greenhouse gases as the soil thaws, further fueling global warming. But scientists haven't known exactly how much carbon is stored in the Arctic permafrost. In a new study detailed online on Aug. 24 in the journal Nature Geoscience, researchers factored in carbon amounts from lower depths of the permafrost than had been included in previous studies. They calculated that the North American Arctic contains 60 percent more carbon than previously estimated. "Releasing even a portion of this carbon into the atmosphere … would have a significant impact on Earth's climate," said Christian Beer, of the Max Planck Institute for Biogeochemistry in Germany, in an accompanying editorial. Beer was not involved in the study.