Lugato Emanuele, Smith Pete, Borrelli Pasquale, Panagos Panos, Ballabio Cristiano, Orgiazzi Alberto, Fernandez-Ugalde Oihane, Montanarella Luca, Jones Arwyn
European Commission, Joint Research Centre, Sustainable Resources Directorate, Via E. Fermi 2749, I-21027 Ispra (VA), Italy.
Institute of Biological and Environmental Sciences, University of Aberdeen, 23 St. Machar Drive, Aberdeen AB24 3UU, UK.
Sci Adv. 2018 Nov 14;4(11):eaau3523. doi: 10.1126/sciadv.aau3523. eCollection 2018 Nov.
Understanding of the processes governing soil organic carbon turnover is confounded by the fact that C feedbacks driven by soil erosion have not yet been fully explored at large scale. However, in a changing climate, variation in rainfall erosivity (and hence soil erosion) may change the amount of C displacement, hence inducing feedbacks onto the land C cycle. Using a consistent biogeochemistry-erosion model framework to quantify the impact of future climate on the C cycle, we show that C input increases were offset by higher heterotrophic respiration under climate change. Taking into account all the additional feedbacks and C fluxes due to displacement by erosion, we estimated a net source of 0.92 to 10.1 Tg C year from agricultural soils in the European Union to the atmosphere over the period 2016-2100. These ranges represented a weaker and stronger C source compared to a simulation without erosion (1.8 Tg C year), respectively, and were dependent on the erosion-driven C loss parameterization, which is still very uncertain. However, when setting a baseline with current erosion rates, the accelerated erosion scenario resulted in 35% more eroded C, but its feedback on the C cycle was marginal. Our results challenge the idea that higher erosion driven by climate will lead to a C sink in the near future.
由于土壤侵蚀驱动的碳反馈尚未在大尺度上得到充分研究，这一事实使得人们对控制土壤有机碳周转过程的理解变得复杂。然而，在气候变化的背景下，降雨侵蚀力的变化（进而导致土壤侵蚀）可能会改变碳的迁移量，从而对陆地碳循环产生反馈作用。我们使用一个一致的生物地球化学 - 侵蚀模型框架来量化未来气候对碳循环的影响，结果表明在气候变化下，碳输入的增加被更高的异养呼吸所抵消。考虑到由于侵蚀导致的所有额外反馈和碳通量，我们估计在2016 - 2100年期间，欧盟农业土壤向大气净排放碳的量在0.92至10.1太克碳/年之间。与不考虑侵蚀的模拟结果（1.8太克碳/年）相比，这些范围分别代表了较弱和较强的碳源，并且取决于侵蚀驱动的碳损失参数化，而这仍然非常不确定。然而，以当前侵蚀率设定基线时，加速侵蚀情景导致侵蚀的碳增加了35%，但其对碳循环的反馈作用微不足道。我们的结果对气候导致的更高侵蚀率在不久的将来会导致碳汇这一观点提出了挑战。
