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Abstract

What are the key findings for policy makers? Article 1 of the UN Convention to Combat Desertification (UNCCD), ratified in March 2020 by 197 countries, identifies soil erosion as a primary cause of land degradation, which, in turn, contributes to poverty and inequality through its negative effects on agriculture, food security, and ecosystems (34). Scientific evidence suggests that global warming has already increased global economic inequality (35) and influenced immigration waves (36). The remarkable increases predicted in the combined future land use and climate change scenarios could have a wide range of negative effects at global, regional, and country levels for which this strategic analysis is intended, and not the field or catchment scale. The first and most obvious consideration emerging from this analysis is the possible exacerbation of the climatic conditions, which could substantially increase global soil erosion (+30%) already in the low GHG emission scenario (SSP1-RCP2.6). A climate-induced increase in soil erosion, as indicated by our findings, with associated land degradation and loss of key ecosystem services (9), would pose a serious threat to the achievement of a large set of targets defined by the UN strategy with the SDGs. This is particularly true for achieving 1) a land degradation neutral world by 2030 (Goal 15; Target 15.3); 2) maintaining soil quality for achieving food security (Goal 2); 3) ensuring availability and sustainable management of water resources (Goal 6); as well as 4) ending poverty (SDG 1); 5) reducing inequality (SDG 10); and 6) taking action to combat global warming (SDG 13).

How can soil erosion be mitigated? According to present knowledge, a climate-induced global increase in water erosion of such a range of magnitude could be difficult to mitigate through CA.

How do the impacts of soil erosion propagate through the ecosystem? Maintaining soil in good health is a primary concern to farmers but the effects of soil erosion go beyond the loss of fertile land. Recognizing the link between erosion and trends of biodiversity and ecosystem service supply, the UN Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services (IPBES) is calling for contributions to understand the service of sediment retention provided by natural landscapes at a global scale.

Some of sub-Saharan Africa indicates signs of considerable demographic expansion (40) with net migration flow. Future exacerbation of lands already degraded losing their ecosystem functioning and experiencing decreased agricultural productivity may aggravate the processes that displace human beings. Most of the erosion increase will occur in low-income countries that suffer from poverty and that will generally tend to be more negatively affected by climate change. To avoid the worst, it is pivotal for countries, especially in the Global South, to support the diffusion of sustainable farming practices.

It is of general interest to all countries around the world to avoid a decrease in agricultural productivity (41). According to our preliminary estimates given here, the effect of climate change will likely be so pronounced that it will overwhelm the mitigation potential of adopting soil-conserving agricultural practices. Still, without a change in agricultural practices, the effect would be multiple times worse. Countries have powerful options to positively influence their rates of soil erosion (42). Countries thus have both an incentive and a toolbox of potential measures to mitigate their soil erosion rates. Given the growing challenge of soil erosion, it is important to act now, act fast, and act comprehensively. Only by doing this through agricultural policy, interventions, and better soil governance will we ensure management to protect the health of our food production and riverine ecosystems.

The study area comprises the land surface of 202 countries for which the Food and Agriculture Organization Corporate Statistical Database (FAOSTAT) (www.fao.org/faostat/en/) currently offers statistics. The modeling area totals about 143 million km2 (∼95.5% of the Earth’s land surface), currently providing living space for a global population of ca. 7.5 billion people and estimated to rise to about 9 billion around 2070.


Land use and climate change impacts on global soil erosion by water (2015-2070)
Pasquale Borrelli, David A. Robinson, Panos Panagos, Emanuele Lugato, Jae E. Yang, Christine Alewell, David Wuepper, Luca Montanarella, Cristiano Ballabio
Proceedings of the National Academy of Sciences Aug 2020, 202001403; DOI: 10.1073/pnas.2001403117