Rapid Arctic warming is accelerating permafrost thaw and mobilizing previously frozen organic carbon (OC) into waterways. Upon thaw, permafrost-derived OC can become susceptible to microbial degradation that may lead to greenhouse gas emissions (GHG), thus accelerating climate change. Abrupt permafrost thaw (e.g., riverbank erosion, retrogressive thaw slumps) occurs in areas rich in OC. Given the high OC content and the increase in frequency of abrupt thaw events, these environments may increasingly contribute to permafrost GHG emissions in the future. To better assess these emissions from abrupt permafrost thaw, we incubated thaw stream waters from an abrupt permafrost thaw site (Duvanny Yar, Siberia) and additionally, waters from their outflow to the Kolyma River. Our results show that CO