Human-induced erosion has offset one-third of carbon emissions from land cover change

Abstract

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Anthropogenic land cover change (ALCC) is an important carbon (C) loss mechanism, but current methods do not consider the role of accelerated soil organic C erosion and its burial in sediments in their assessments of net soil-atmosphere C exchange. Using a comprehensive global database and parsimonious modelling, we evaluate the impact of anthropogenic soil erosion on C fluxes between the Earth's surface and atmosphere from the onset of agriculture to the present day. We find that agricultural erosion represents a very large and transient perturbation to the C cycle and has induced a cumulative net uptake of 78 ± 22 Pg C in terrestrial ecosystems during the period 6000 BC to AD 2015. This erosion-induced soil organic C sink is estimated to have offset 37 ± 10% of previously recognized C emissions resulting from ALCC. We estimate that rates of C burial have increased by a factor of 4.6 since AD 1850. Thus, current assessments may significantly overestimate both past and future anthropogenic emissions from the land. Given that ALCC is the most uncertain component of the global C budget and that there is a strong connection between ALCC and erosion, an explicit representation of erosion and burial processes is essential to fully understand the impact of human activities on the net soil-atmosphere C exchange.