Limitations of soil degradation on the planet

Healthy soils have resilience that allows them structure and function to withstand repeated disturbances.^8,9Temperature perturbation¹⁰Compaction¹¹Copper pollution¹². They provide essential ecosystem service³These include food production, which can help us reach several Sustainable Development Goals including zero hunger, clean water, sanitation, life on the land, flood regulation, conservation of biodiversity, and clean water.¹³. However, soil resilience is being compromised by human-caused degradation (Fig.1).^3,14. The greatest threats to healthy soils are population growth, unsustainable agricultural practices and deforestation.^3,14,15. Soils that have been disturbed beyond a critical level are at risk of going into a downward spiral to an alternative, degraded condition.^9,14. This state is marked by a loss in soil functions and services, including the ability to provide food and sustain life on Earth.^14,16. Because soil restoration can take a long time, it is often considered a nonrenewable resource.^6,9,14,15.

The main drivers and quantifiable threats to soil degradation and their consequences on societal and planetary health are the key indicators of soil degradation.

The downward spiral in soil degradation is fuelled by soil threats that are strongly interrelated, and linked through powerful feedback channels. Loss of soil structure from heavy machinery or intensive grazing can lead to soil biota loss and further degradation at a local level.¹⁷. Globally, there is a strong positive feedback between soil erosion and climate changes. Global warming is caused when soil erosion results in a loss of soil organic matter.¹⁴. Warmer conditions can lead to an increase in rainfall intensity, wind speed and wildfire, which can all contribute to soil erosion.^14,18.

It is not uncommon to find soil conditions that are poor in human history. Poor soil protection has been linked with the fall of civilizations in the past.¹⁹. One of these was the collapse of the Sumerian civilization in Mesopotamia by salinization or upland erosion¹⁹Both Ancient Greece as well as the Roman Empire were affected by widespread, severe soil erosion.¹⁹. While healthy soils allow for the growth of civilizations and their prosperity, severe soil degradation occurs when there is an increase in food production and unsustainable agricultural practices. Soil degradation leads to a decline of food security and political stability that compromises the resilience of civilizations, and eventually causes their collapse.¹⁹. However, in the past, the human population was smaller and more scattered than it is today.⁶. This means that the past impacts of soil degrading only harmed local ecosystems, and societies. Soil degradation is no longer a local problem today, with a population of 7.9 billion that is expected increase to 9.8 billion by 2050.⁶. At least 3.2 billion people around the world are already suffering from land degradation.²⁰This decrease in food security and landscape resilience to extreme weather events can lead to an increase in inequality as well as political instability.^15,20. The annual costs of soil degradation in the European Union exceed 50 billion euros¹⁵. Globally, soil degrading has been linked with mass migrations, violence, armed conflict, and other forms of human-caused destruction.^19,20. Globally, soil degradation will affect 90% of soils by 2050³This means that almost all global ecosystems will be directly affected.