It means that if we overestimated the soil response to warming then we must have underestimated something else dramatically because we have a net effect of faster global warming.

CNN: Soil study hints at climate model revision

These changes may have resulted in earlier snow melt and exposure of darker rocks, soil and sea ice, leading to warming throughout Greenland in the late 19th and early 20th Centuries when soot levels were at their highest.

BBC: Human activities have left a visible mark on the Arctic