Soil organic carbon (SOC) stores and the pattern of distribution were studied along an ecological gradient in the Arctic region of Canada and Alaska. SOC stores increases with decreasing latitudes (down to 68oN) due to increased biomass production. In the past the SOC in arctic soils was grossly underestimated because of the shallow depth of excavation thus only SOC in the active layers were accounted for. In recent studies, it was found that the non-sorted circles are the dominant microtopographic features in the arctic tundra from the sparsely vegetated Subzone A in the High Arctic to the shrub dominated Subzone F in the Low Arctic. A second layer of SOC caused by cryoturbation was consistently found at the bottom of the active layer and upper permafrost throughout the studied areas. Based on C-14 dating, most of this deep SOC started to accumulate in early Holocene. In most soils the SOC in this second layer is nearly half or in some cases more than half of the total pedon SOC. Thus, the cryopedogenic processes, mainly non-sorted circle formation, become the controlling factors in carbon sequestration in arctic tundra soils. With this “deep” carbon accounted for, the estimates for the total SOC stores in the circumpolar regions should be doubled. Since this “deep” carbon is at the upper permafrost that is sensitive to climate change, this portion of SOC must be accounted for in the prediction of the impact of climatic warming on global carbon cycling.