# 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 (medium confidence). Soil erosion from agricultural fields is estimated to be currently 11 to 20 times (no-tillage) to more than 100 times (conventional tillage) higher than the soil formation rate (medium confidence)."
The United Nations estimate 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.

## Types

In addition to the usual types of land degradation that have been known for centuries (water, wind and mechanical erosion, physical, chemical and biological degradation), 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.
Overall, more than 36 types of land degradation can be assessed. All are induced or aggravated by human activities, e.g. soil erosion, soil contamination, soil acidification, sheet erosion, silting, aridification, salinization, urbanization, etc.
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.

### Solar power systems

Solar power is widely considered as an alternative, sustainable, and renewable energy source compared to fossil fuels. However, it has adverse environmental impacts. There are six types of impacts:
* Soil erosion, the construction of solar plants requires vegetation removal, land grading, soil compaction, and construction of access roads all of which contribute to soil erosion. Additionally, changes in the natural landscape can lead to an increased in stormwater runoff further exacerbating soil erosion.
* Water, usage of water occurs at all stages of a solar plant's development (construction, operation, and decommissioning) in the form of dust suppression, cooling, and cleaning. Concentrating solar power (CSP) in particular, generally requires excessive water usage for cooling purposes. For this reason alone, solar plant sites and their water consumption should be closely examined as access to freshwater becomes more scarce.
* Emissions, solar energy systems do not emit carbon into the atmosphere during operation directly. However, no human development project can completely avoid some impacts on the environment, solar plants can be indirectly connected to the manufacturing, transportation, and construction.
* Hazardous waste, the manufacturing of photovoltaic (PV) cells include a number of hazardous materials. Such materials include, compounds of cadmium (Cd), selenium (Se), and lead (Pb).
* Vegetation and wildlife, both are directly and indirectly impacted through solar power plant constructions. Large scale solar plants requires intense clearing of land, which affects native vegetation, habitat, and ultimately, the loss of wildlife. The construction of utility-scale solar energy (USSE) contributes to avian mortality. USSE-related avian mortality was estimated to be between 16,200 and 59,400 birds in the Southern California region. This statistic was extrapolated to be between 37,800 and 138,600 birds for all USSE facilities across the United States. Solar energy plants are being constructed in a wide range of environments and ecosystems such as forests, grasslands, deserts, and farmlands. Forests typically have the highest levels of biodiversity, biomass density, and cloud cover therefore construction of solar energy plants in these regions will have the most adverse effects on vegetation and wildlife.
* Land use footprint, in comparison to fossil fuel based plants, solar energy plants have higher land use efficiency. Land use efficiency of solar energy plants can be further minimize by construction plants in abandoned mines or in conjunction with other renewable energy operations such as wind or facilities such as a water treatment plant.

### Wind power systems

Similar to previous, wind power is also a relatively clean source of energy but it also has adverse environmental impacts. There six types of impacts:
* Visual, typically located in rural or natural regions, wind energy power plants are commonly viewed as an opposing element to the natural landscape and is associated with industry among local residents and environmental activists.
* Noise, there are two types of noises produced by wind turbines, aerodynamic and mechanical. Aerodynamic noise comes from turbine blades circulating. This type of noise is varied and based on the size of turbines, wind speed, and blade rotation speed. Mechanical noise comes from the turbine's internal mechanisms and parts. This type is varied by the quality of sound insulation. Unlike aerodynamic noise, mechanical noise does not increase with the overall size of wind turbines. Additionally, reported health problems attributed to noise from wind turbines include a list of symptoms such as sleep disorders, headaches, mood disorders, inability to concentrate, tinnitus, and vestibular problems.
* Electromagnetic interference, wind turbines can cause disruption to local radios, television, microwave communication systems, and navigational systems by generating electromagnetic interferences.
* Local climate, wind masses that move through the blades of a wind turbine experience losses in momentum. This change in atmospheric dynamics could lead to increased in temperature of the surrounding environment due to weaker winds that would otherwise provide cooling affects.
* Vegetation and wildlife, similar to solar plants, wind turbine plants also require large scale clearing of land, vegetation, soil erosion all of which will result in adverse effects on wildlife. Wind turbine plants can directly impact mortality of wildlife (birds and bats) through collision mortality and indirectly through loss of habitats.
* Wind turbines on farmlandLand use footprint, the use of land for wind turbines depends on the terrain with flatter areas requiring more land than those in hilly areas. Wind turbine plants can operate in conjunction with other land use such as agriculture and solar without affecting energy production.

## 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;
** Monocultures which destabilize the local ecosystem;
** Poor livestock farming practices such as overgrazing (the grazing of natural pastures at stocking intensities above the livestock carrying capacity);
** Inappropriate irrigation
* Climate change because it can "exacerbate land degradation, particularly in low-lying coastal areas, river deltas, drylands and in permafrost areas"
High population density is not always related to land degradation. Rather, it is the practices of the human population that can cause a landscape to become degraded.
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 (IPCC) climate change is one of the causes of land degradation. The report state that: "Climate change exacerbates land degradation, particularly in low-lying coastal areas, river deltas, drylands and in permafrost areas (high confidence). Over the period 1961–2013, the annual area of drylands in drought has increased, on average by slightly more than 1% per year, with large inter-annual variability. In 2015, about 500 (380–620) million people lived within areas which experienced desertification between the year 1980s and 2000s. The highest numbers of people affected are in South and East Asia, the circum Sahara region including North Africa, and the Middle East including the Arabian Peninsula (low confidence). Other dryland regions have also experienced desertification. People living in already degraded or desertified areas are increasingly negatively affected by climate change (high confidence)." 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 (LDN 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 (soil focus) 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.

### Sensitivity and resilience

Sensitivity and resilience are measures of the vulnerability of a landscape to degradation. These two factors combine to explain the degree of vulnerability. Sensitivity is the degree to which a land system undergoes change due to natural forces, human intervention or a combination of both. Resilience is the ability of a landscape to absorb change, without significantly altering the relationship between the relative importance and numbers of individuals and species that compose the community. It also refers to the ability of the region to return to its original state after being changed in some way. The resilience of a landscape can be increased or decreased through human interaction based upon different methods of land-use management. Land that is degraded becomes less resilient than undegraded land, which can lead to even further degradation through shocks to the landscape.

## 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."

### Public awareness and education

Increasing public awareness about the importance of land conservation, sustainable land management, and the consequences of land degradation is vital for fostering behavioral change and mobilizing support for action. Education, outreach campaigns, and knowledge-sharing platforms can empower individuals, communities, and stakeholders to adopt more sustainable practices and become stewards of the land.