Permafrost rivers emit mostly pre-aged carbon on the Qinghai-Tibet Plateau under climate warming

This is the authors' abstract. We don't add key points for this paper.

Climate-sensitive alpine permafrost rivers on the Qinghai-Tibet Plateau export pre-aged carbon (C), yet the role of this pre-aged C in greenhouse gas emissions remains unclear. Here, through radiocarbon analysis of riverine CO 2 , CH 4 , dissolved organic carbon (DOC), and sediment organic carbon (SOC), we show that DOC and SOC originate primarily from pre-aged C, and it is more readily degraded than modern C due to lower aromaticity, with microorganisms preferentially metabolizing permafrost-derived fractions. Pre-aged C accounts for >60% of both CO 2 and CH 4 emissions. CO 2 derives mainly from pre-aged active layer C decomposition, with increased terrigenous fresh CO 2 input entering rivers during the growing season. Notably, ancient permafrost C contributes up to ∼30.5% of total CH 4 emissions. Our findings highlight that ancient C released by alpine permafrost rivers substantially contributes to greenhouse gas emissions, emphasizing the need to improve global C models and formulate climate-resilient mitigation frameworks to support sustainable development.