Peatlands are stores of atmospheric carbon, as well as natural and industrial toxic metals and metalloids (TMMs), such as lead or arsenic. The long-term sequestration of both carbon and TMMs in peatlands is increasingly threatened due to climate change-enhanced smouldering peat fires. However, estimates of carbon and TMMs emissions from northern peatland smouldering fires are poorly resolved, nor is there a clear quantification of how these emissions may increase under climate change. We developed a spatially explicit and physically based model framework to estimate contemporary and future emissions of carbon and TMMs from northern peatlands using known peat properties, peatland distribution, and TMM concentrations. We estimate, on average, smouldering peat fires currently emit ~34 Mt C yr-1 and will increase to 57 ± 8 and 60 ± 15 Mt C yr-1 by 2070 in both ssp245 and ssp370, respectively. However, the increase in precipitation in ssp585, the most extreme climate change scenario tested, resulted slightly lower smouldering carbon emissions by 2070 (58 ± 12 Mt C yr-1). The emission of TMMs during smouldering peat fires is tightly linked to the particulate carbon emissions (PM2.5). By coupling our modelled carbon emissions to PM2.5 and TMM emission factors, we show that, for example, contemporary northern peat fires emit ~4 t Pb yr-1 and is projected to increase by ~5× by 2070 under ssp585 climate change scenario. With the increase of burned area and severity under a warming climate, we argue we can no longer ignore this impending environmental and human health disaster.