Arctic coastal permafrost erosion is projected to increase by a factor of 2–3 by 2100. However, organic matter fluxes from the coastal permafrost into the ocean have not been considered in Earth system models so far. Here we represent coastal permafrost erosion in an Earth system model and perform simulations with varying permafrost organic matter properties, such as sinking fraction and nutrient content. We find that coastal erosion reduces the Arctic Ocean CO₂ uptake from the atmosphere in all simulations: by 4.6–13.2 TgC yr⁻¹ by 2100, which is ~7–14% of the Inner Arctic Ocean uptake. We show that coastal permafrost erosion exerts a positive biogeochemical feedback on climate, increasing atmospheric CO₂ by 1–2 TgC yr⁻¹ per °C of increase in global surface air temperature. Our work will allow coastal permafrost erosion to be considered in future climate change assessments.

预计到 2100 年，北极沿海永久冻土侵蚀将增加 2-3 倍。然而，迄今为止，地球系统模型尚未考虑从沿海永久冻土进入海洋的有机物通量。在这里，我们在地球系统模型中表示沿海永久冻土侵蚀，并使用不同的永久冻土有机物特性（例如下沉分数和营养物含量）进行模拟。我们发现，在所有模拟中，海岸侵蚀都会减少北冰洋从大气中吸收的 CO ₂ ：到 2100 年，减少 4.6–13.2 TgC yr ^-1 ，相当于内北冰洋吸收量的 7–14%。我们表明，沿海永久冻土侵蚀对气候产生积极的生物地球化学反馈，全球表面气温每升高°C，大气中的CO ₂就会增加1-2 TgC yr ^-1 。我们的工作将使沿海永久冻土侵蚀能够在未来的气候变化评估中得到考虑。