The Arctic is currently a major research focal point, because temperatures in this region have been projected to increase up to 7.5ºC under global warming scenarios.  Such temperature increases lead to greater soil microbial activity, soil organic matter decomposition and ultimately atmospheric CO₂ emissions.  This study quantified soil C, nitrogen (N) and microbial community dynamics under climate change scenarios [ambient (14ºC), experimental (21ºC)], using an organo-mineral soil [Wolf Basin (WB)] and an organic soil [Peat Canyon (PC)] at the Daring Lake Research Station.  Soil organic C and N pools (kg/ha) and content (%) were significantly different (p<0.05) between soil horizons at WB, but no such difference was found at PC.   The soil profile at WB showed a significant (p<0.05) enrichment in ¹³C and ¹⁵N with depth, although no such difference occurred at PC.  The CO₂ rate flux was significantly greater (p>0.05) at 21ºC in WB (27 mg/g/d) and PC (39 mg/g/d) compared to that at 14ºC (14 mg/g/d WB, 22 mg/g/d PC).  The CO₂ rate flux was significantly different (p<0.05) between soil horizons at both sites and temperatures.  The greatest rate flux occurred in the organic and organo-mineral horizons, whereas the C horizon was a net CO₂ sink.  All soil horizons, except for the mineral soil showed a significant (p<0.05) enrichment in ¹³C-CO₂ with time.  At time 0, the mean microbial community metabolic diversity (CMD) showed the slowest change in the Bm horizon at WB.  However, after 85 days, the Bm horizon showed the most rapid change in CMD at 21ºC, whereas this change was much slower at 14ºC.  At WB, the SOC pool was significantly greater in the Bm horizon compared to the O horizon, this in combination with a relatively low C:N ratio (24), may have led to a greater rate flux of CO₂ and a more rapid change in the CMD at 21ºC compared to the remaining horizons at this site.  Therefore, under climate change scenarios, C stored in lower horizons can become a major source of CO₂.