Land degradation
Land degradation is a process where land becomes less healthy and productive due to a combination of human activities or natural conditions. The causes for land degradation are numerous and complex. Human activities are often the main cause, such as unsustainable land management practices. Natural hazards are excluded as a cause; however human activities can indirectly affect phenomena such as floods and wildfires.
One of the impacts of land degradation is that it can diminish the natural capacity of the land to store and filter water leading to water scarcity. Human-induced land degradation and water scarcity are increasing the levels of risk for agricultural production and ecosystem services.
The United Nations estimate that about 30% of land is degraded worldwide, and about 3.2 billion people reside in these degrading areas, giving a high rate of environmental pollution. Land degradation reduces agricultural productivity, leads to biodiversity loss, and can reduce food security as well as water security. It was estimated in 2007 that up to 40% of the world's agricultural land is seriously degraded, with the United Nations estimating that the global economy could lose $23 trillion by 2050 through degradation.
Definition
As per the Millennium Ecosystem Assessment of 2005, land degradation is in defined as "the reduction or loss of the biological or economic productivity of drylands". A similar definition states that land degradation is the "degradation, impoverishment and long-term loss of ecosystem services".It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable.
Scale
According to the Special Report on Climate Change and Land of the Intergovernmental Panel on Climate Change in 2019: "About a quarter of the Earth's ice-free land area is subject to human-induced degradation. Soil erosion from agricultural fields is estimated to be currently 11 to 20 times to more than 100 times higher than the soil formation rate."The United Nations estimated in 2014 that ~30% of land is degraded worldwide, and ~3.2 billion people reside in these degrading areas, giving a high rate of environmental pollution. Approximately 12 million hectares of productive land—which roughly equals the size of Greece—is degraded every year. This is due to the socio-economic exploitation of lands without proper planning for long-term sustainability.
In 2021, estimates claim that two thirds of Africa's productive land area are severely affected by land degradation.
In 2024, the United Nations claimed that 75% of soils are degraded at some extent. By the year 2050 the share of degraded land can rise to 90%, if current trends continue. During the years 2015-2019 around 100 million hectares of soil were degraded every year. The Global Environment Facility suggested that 95% of soil can degrade by 2050.
Types
In addition to the usual types of land degradation that have been known for centuries, four other types have emerged in the last 50 years:- pollution, often chemical, due to agricultural, industrial, mining or commercial activities;
- loss of arable land due to urban construction, road building, land conversion, agricultural expansion, etc.;
- artificial radioactivity, sometimes accidental;
- land-use constraints associated with armed conflicts.
A problem with defining land degradation is that what one group of people might view as degradation, others might view as a benefit or opportunity. For example, planting crops at a location with heavy rainfall and steep slopes would create scientific and environmental concern regarding the risk of soil erosion by water, yet farmers could view the location as a favourable one for high crop yields.
Causes
Land degradation is mainly derived by numerous, complex, and interrelated anthropogenic and/or natural proximate and underlying causes. For example, in Ethiopia the country has been affected by chronic and ongoing land degradation processes and forms. The major proximate drivers are biophysical factors and unsustainable land management practices, while the underlying drivers are social, economic, and institutional factors.Land degradation is a global problem largely related to the agricultural sector, general deforestation and climate change. Causes include:
- Land clearance, such as clearcutting, overlogging and deforestation
- Agricultural activities such as:
- * Activities that lead to depletion of soil nutrients through poor farming practices such as exposure of naked soil after crop harvesting or deep plowing ;
- * Inappropriate irrigation
- Pollution of soil as a result of littering, urbanization, mining, oil spills, pesticides, herbicides, fertilizers and animal waste.
- Climate change because it can "exacerbate land degradation, particularly in low-lying coastal areas, river deltas, drylands and in permafrost areas"
Severe land degradation affects a significant portion of the Earth's arable lands, decreasing the wealth and economic development of nations. As the land resource base becomes less productive, food security is compromised and competition for dwindling resources increases, the seeds of famine and potential conflict are sown.
Climate change and land degradation
According to the Special Report on Climate Change and Land of the Intergovernmental Panel on Climate Change climate change exacerbates land degradation, especially in low-lying coastal areas, river deltas, drylands and permafrost areas. During the years 1961–2013, the area of drylands in drought rose by more than 1% per year. In 2015, about 500,000,000 people lived in areas which experienced desertification in the years 1980s - 2000s. People living in those areas are severely impacted by climate change. Additionally, it is reported that 74% of the poor are directly affected by land degradation globally.Significant land degradation from seawater inundation, particularly in river deltas and on low-lying islands, is a potential hazard that was identified in a 2007 IPCC report.
As a result of sea-level rise from climate change, salinity levels can reach levels where agriculture becomes impossible in very low-lying areas.
In 2009 the European Investment Bank agreed to invest up to $45 million in the Land Degradation Neutrality Fund. Launched at UNCCD COP 13 in 2017, the LDN Fund invests in projects that generate environmental benefits, socio-economic benefits, and financial returns for investors. The Fund was initially capitalized at US$100 million and is expected to grow to US$300 million.
In the 2022 IPCC report, land degradation is responding more directly to climate change as all types of erosion and SOM declines are increasing. Other land degradation pressures are also being caused by human pressures like managed ecosystems. These systems include human run croplands and pastures.
Impacts
Land degradation takes many forms and affects water and land resources. It can diminish the natural capacity of the land to store and filter water leading to water scarcity.The results of land degradation are significant and complex. They include lower crop yields, less diverse ecosystems, more vulnerability to natural disasters like floods and droughts, people losing their homes, less food available, and economic problems. Degraded land also releases greenhouse gases, making climate change worse.
Further possible impacts include:
- A temporary or permanent decline in the productive capacity of the land. This can be seen through a loss of biomass, a loss of actual productivity or in potential productivity, or a loss or change in vegetative cover and soil nutrients.
- Loss of biodiversity: A loss of range of species or ecosystem complexity as a decline in the environmental quality.
- Increased vulnerability of the environment or people to destruction or crisis.
- Wars and conflicts. Degradation of soil is one of the factors which increase competition over agricultural land, and all except 3 conflicts inside states in Africa from the 1990s are linked to such competition.
- Environmental migration
Sensitivity and resilience
Prevention
Sustainable land management
Actions to halt land degradation can be broadly classified as prevention, mitigation, and restoration interventions.Sustainable land management has been proven in reversing land degradation. It also ensures water security by increasing soil moisture availability, decreasing surface runoff, decreasing soil erosion, leading to an increased infiltration, and decreased flood discharge.
The United Nations Sustainable Development Goal 15 has a target to restore degraded land and soil and achieve a land degradation-neutral world by 2030. The full title of Target 15.3 is: "By 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world."