## 1 Introduction  
As a natural geological process, soil erosion over eons has created the world's most fertile alluvial and aeolian (loess) soils. Acceleration of the natural erosion process by human activities, ever since the dawn of settled agriculture ~12 millennia ago, has caused the most severe environmental problems of the 21 st century. Soil erosion, involving breakdown and transport of soil particles, requires energy, and a specific type of erosion depends on the source of energy (Figure 1). Water and wind are among the principal sources of energy, and thus major factors of erosion. Being a selective process, soil erosion removes and transports fine (i.e., clay and silt) and light (soil organic carbon or SOC) fractions. These three constituents (i.e., clay, silt, and SOC) are also key determinants of soil quality, and its capacity to provide numerous ecosystem services (ESs). However, these essential constituentsare depleted over time in soils prone to accelerated erosion. The latter has plagued the Earth and humanity for millennia. The data based on the analysis of sediments from 600 lakes worldwide show that anthropogenic activities accelerated global soil erosion 4000 years ago [1]. Many once-thriving civilizations vanished because they treated their soil like dirt [2;3]. The current problem of accelerated soil erosion is driven by a rapid and an indiscriminate expansion of agroecosystems for feeding the growing population. Further, the problem of soil erosion is also exacerbated by anthropogenic global warming [4;5]. In addition to adversely impacting the wellbeing of 3.2 billion people [6], accelerated soil erosion is also polluting the environment (i.e., soil, water, and air). It affects and is affected by the present and will be aggravated by the projected climate change. Under natural ecosystems, SOC stock is a sink of atmospheric carbon dioxide (CO\({}_{2}\)), and is protected against microbial processes through the formation of organo-mineral complexes and stable structural units or aggregates. Conversion of natural to managed ecosystems disrupts aggregates, exposes the hitherto protected SOC, and increases its vulnerability to transport by erosion and decomposition by microbial processes. Preferentially removed light SOC fraction is redistributed over the landscape, deposited in channels and transported to aquatic ecosystems and depressional sites (Figure 2). The labile SOC fraction is exposed to microbial processes when being transported, and following after redistribution and deposition phases of the erosion process. Furthermore, the historic land use based on extractive farming practices also mined off the SOC stock as a source of plant nutrients. Thus, soils of most agroecosystems are depleted of their original SOC stock. Consequently, soil quality is degraded, the capacity to perform ESs is impaired, and the environment (i.e., soil, water, air, and biodiversity) jeopardized. Figure 1: Types of soil erosion driven by source of energy. The global magnitude of historic depletion of SOC by all processes may be as much as 135 Pg C [7]. Consequently, degraded and depleted soils also have a large carbon (C) sink capacity to reabsorb atmospheric CO\({}_{2}\) into SOC stock upon conversion to a restorative land use and adoption of conservation-effective practices. It is this potential of restoring the global SOC stock, for advancing food and climate security and strengthening soils' capacity to provide ESs, that sustainable soil management is receiving the attention of policymakers. Ever since the launch of the 4 Per Thousand (4P1000) initiative at COP 21 in Paris in 2015 [8], world soils have been on the global agenda as an option to sequester C and mitigate global warming. Such initiatives are aimed at achieving greenhouse gas (GHG) neutrality through low-carbon farming [9]. Transport of C by accelerated soil erosion at a global scale is one such process that impacts the emission of CO\({}_{2}\), methane (CH\({}_{4}\)), and nitrous oxide (N\({}_{2}\)O).