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Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability. [1] [2] [3] [4] These areas tend to fall upon degraded soils, and their health and functioning are key necessities of regulating ecosystems’ atmospheric components. [5] [3]
The distribution of aridity at any time is largely the result of the general circulation of the atmosphere. The latter does change significantly over time through climate change. For example, temperature increase by 1.5–2.1 percent across the Nile Basin over the next 30–40 years could change the region from semi-arid to arid, significantly reducing the land usable for agriculture. In addition, changes in land use can increase demands on soil water and thereby increase aridity. [6]
A December 2024 report from the UNCCD concluded that more than three-quarters of the Earth's land "has become permanently dryer in recent decades", that "drier climates now affecting vast regions across the globe will not return to how they were", and that a quarter of the global population lives in expanding drylands. [7]
Desertification is a type of gradual land degradation of fertile land into arid desert due to a combination of natural processes and human activities.
Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean. It can also come about through artificial processes such as irrigation and road salt.
Rio Convention relates to the following three conventions, which were agreed at the Earth Summit held in Rio de Janeiro in June 1992.
Dryland farming and dry farming encompass specific agricultural techniques for the non-irrigated cultivation of crops. Dryland farming is associated with drylands, areas characterized by a cool wet season followed by a warm dry season. They are also associated with arid conditions, areas prone to drought and those having scarce water resources.
Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defined as any change or disturbance to the environment perceived to be deleterious or undesirable. The environmental degradation process amplifies the impact of environmental issues which leave lasting impacts on the environment.
Rangelands are grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savannas, chaparrals, steppes, and tundras. Rangelands do not include forests lacking grazable understory vegetation, barren desert, farmland, or land covered by solid rock, concrete, or glaciers.
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.
The term Southern Australia is generally considered to refer to the states and territories of Australia of New South Wales, Victoria, Tasmania, the Australian Capital Territory and South Australia. The part of Western Australia south of latitude 26° south — a definition widely used in law and state government policy — is also usually included.
Worldwide more human beings gain their livelihood from agriculture than any other endeavor; the majority are self-employed subsistence farmers living in the tropics. While growing food for local consumption is the core of tropical agriculture, cash crops are also included in the definition.
The Great Green Wall or Great Green Wall for the Sahara and the Sahel is a project adopted by the African Union in 2007, initially conceived as a way to combat desertification in the Sahel region and hold back expansion of the Sahara desert, by planting a wall of trees stretching across the entire Sahel from Djibouti, Djibouti to Dakar, Senegal. The original dimensions of the "wall" were to be 15 km wide and 7,775 km long, but the program expanded to encompass nations in both northern and western Africa. The concept evolved into promoting water harvesting techniques, greenery protection and improving indigenous land use techniques, aimed at creating a mosaic of green and productive landscapes across North Africa. Later it adopted the view that desert boundaries change based on rainfall variations.
Rhodes Whitmore Fairbridge was an Australian geologist and expert on climate change. His father was Kingsley Fairbridge.
Aridification is the process of a region becoming increasingly arid, or dry. It refers to long term change, rather than seasonal variation.
Agriculture employs the majority of Madagascar's population. Mainly involving smallholders, agriculture has seen different levels of state organisation, shifting from state control to a liberalized sector.
Desert greening is the process of afforestation or revegetation of deserts for ecological restoration (biodiversity), sustainable farming and forestry, but also for reclamation of natural water systems and other ecological systems that support life. The term "desert greening" is intended to apply to both cold and hot arid and semi-arid deserts
. It does not apply to ice capped or permafrost regions. It pertains to roughly 32 million square kilometres of land. Deserts span all seven continents of the Earth and make up nearly a fifth of the Earth's landmass, areas that recently have been increasing in size.The climate of Africa is a range of climates such as the equatorial climate, the tropical wet and dry climate, the tropical monsoon climate, the semi-arid climate, the desert climate, the humid subtropical climate, and the subtropical highland climate. Temperate climates are rare across the continent except at very high elevations and along the fringes. In fact, the climate of Africa is more variable by rainfall amount than by temperatures, which are consistently high. African deserts are the sunniest and the driest parts of the continent, owing to the prevailing presence of the subtropical ridge with subsiding, hot, dry air masses. Africa holds many heat-related records: the continent has the hottest extended region year-round, the areas with the hottest summer climate, the highest sunshine duration, and more.
Drylands are defined by a scarcity of water. Drylands are zones where precipitation is balanced by evaporation from surfaces and by transpiration by plants (evapotranspiration). The United Nations Environment Program defines drylands as tropical and temperate areas with an aridity index of less than 0.65. One can classify drylands into four sub-types:
Michael Mortimore was a British geographer and a prolific researcher of issues in the African drylands. He was an academic in Nigerian universities for over 25 years. He ran a British research consultancy, Drylands Research. He is best known for an anti-Malthusian account of population-environment relationships, More People, Less Erosion, and field-based studies of adaptation to drought.
Caroline King-Okumu is an international development opportunities manager for the UK Centre for Ecology and Hydrology. She was formerly a senior researcher for the International Institute for Environment and Development (IIED). Her major areas of research are dryland ecosystems, economic and environmental assessment, and climate change. She is considered an international expert on land and water management, particularly drylands agriculture. King-Okumu is based in Kenya but is involved in research and projects throughout the world.
The effects of climate change on the water cycle are profound and have been described as an intensification or a strengthening of the water cycle. This effect has been observed since at least 1980. One example is when heavy rain events become even stronger. The effects of climate change on the water cycle have important negative effects on the availability of freshwater resources, as well as other water reservoirs such as oceans, ice sheets, the atmosphere and soil moisture. The water cycle is essential to life on Earth and plays a large role in the global climate system and ocean circulation. The warming of our planet is expected to be accompanied by changes in the water cycle for various reasons. For example, a warmer atmosphere can contain more water vapor which has effects on evaporation and rainfall.
National Tree Growing Day is a public holiday in Kenya. It was inaugurated on November 13, 2023 by Interior Cabinet Secretary, Kithure Kindiki, in accordance with a gazette notice issued on November 6, 2023. This announcement made Kenya the first and only nation to declare a public holiday for this purpose.