Land use and climate change impacts on global soil erosion by water (2015-2070)

Abstract

Soil erosion is a major global soil degradation threat to land, freshwater, and oceans. Wind and water are the major drivers, with water erosion over land being the focus of this work; excluding gullying and river bank erosion. Improving knowledge of the probable future rates of soil erosion, accelerated by human activity, is important both for policy makers engaged in land use decision-making and for earth-system modelers seeking to reduce uncertainty on global predictions. Here we predict future rates of erosion by modeling change in potential global soil erosion by water using three alternative (2.6, 4.5, and 8.5) Shared Socioeconomic Pathway and Representative Concentration Pathway (SSP-RCP) scenarios. Global predictions rely on a high spatial resolution Revised Universal Soil Loss Equation (RUSLE)-based semiempirical modeling approach (GloSEM). The baseline model (2015) predicts global potential soil erosion rates of [Formula: see text] Pg yr^-1, with current conservation agriculture (CA) practices estimated to reduce this by ∼5%. Our future scenarios suggest that socioeconomic developments impacting land use will either decrease (SSP1-RCP2.6-10%) or increase (SSP2-RCP4.5 +2%, SSP5-RCP8.5 +10%) water erosion by 2070. Climate projections, for all global dynamics scenarios, indicate a trend, moving toward a more vigorous hydrological cycle, which could increase global water erosion (+30 to +66%). Accepting some degrees of uncertainty, our findings provide insights into how possible future socioeconomic development will affect soil erosion by water using a globally consistent approach. This preliminary evidence seeks to inform efforts such as those of the United Nations to assess global soil erosion and inform decision makers developing national strategies for soil conservation.

Keywords: agricultural sustainability; land degradation; policy scenarios.

Fig. 1.

Soil erosion estimates predicted through the GloSEM. (A) illustrates the soil erosion rates divided into seven classes according to the European Soil Bureau classification. (B–D) illustrate changes of the annual average soil erosion between 2015 and 2070 for three distinct RCP greenhouse gas trajectories. The changes exclusively refer to effects of land use change. For these simulations, the climate of the year 2015 have been employed. (B–D) share the same legend.

Fig. 2.

Soil erosion change between 2015 and 2070. The delta between the two observed periods [(RCP) greenhouse gas trajectories SSP1-RCP2.6 and SSP5-RCP8.5] depends on the effects of land use and land cover change and climate change.

Fig. 3.

Rainfall erosivity estimates. (A) illustrates the global erosivity map at 30 arc-seconds (∼1 km at the equator) based on a GPR proposed by Panagos et al. (18). (B–D) illustrate changes of the annual rainfall erosivity between 2015 and the 2070 SSP1-RCP2.6 (B), 2070 SSP2-RCP4.5 and 2070 SSP1-RCP2.6 (C), and 2070 SSP5-RCP8.5 and 2070 SSP2-RCP4.5 (D). For the rainfall erosivity scenarios of 2070, average values of the 14 GCMs of the WorldClim database version 1.4 have been considered.

Fig. 4.

Flow diagram of the projected land use and climate changes. (Insets, A–C) demonstrates the projected net change of the land surface (million km²), climate, and soil erosion (Pg yr⁻¹) for the SSP1-RCP2.6 (insert A), SSP2-RCP4.5 (insert B), and SSP5-RCP8.5 (insert C).

Fig. 5.

Fertilizer consumption versus GDP. Fertilizer consumption per hectare (year 2015) versus GDP) per capita (year 2011, expressed in US dollars) and the increase of soil erosion (%) between 2015 and 2070 for the SSP5-RCP 8.5. The magnitude of the increase of soil erosion is indicated by the size of the circles. The color of the circles refers to the continents.