When deserts appear automatically over the natural course of a planet's life cycle, then it can be called a natural phenomenon; however, when deserts emerge due to the rampant and unchecked depletion of nutrients in soil that are essential for it to remain arable, then a virtual soil death can be spoken of, which traces its cause back to human overexploitation.
Desertification is a significant global ecological and environmental problem with far reaching consequences on socio-economic and political conditions.
Considerable controversy exists over the proper definition of the term ‘desertification’ for which Helmut Geist (2005) has identified more than 100 formal definitions. The most widely accepted of these is that of the Princeton University Dictionary which defines it as ‘the process of fertile land transforming into desert typically as a result of deforestation, drought or improper/inappropriate agriculture".
Desertification has been neatly defined in the text of the United Nations Convention to Combat Desertification (UNCCD) as ‘land degradation in arid, semi-arid and dry sub-humid regions resulting from various factors, including climatic variations and human activities.’
A drought or drouth is a natural disaster of below-average precipitation in a given region, resulting in prolonged shortages in the water supply, whether atmospheric, surface water or ground water. A drought can last for months or years, or may be declared after as few as 15 days. It can have a substantial impact on the ecosystem and agriculture of the affected region and harm to the local economy.
Annual dry seasons in the tropics significantly increase the chances of a drought developing and subsequent bush fires. Periods of heat can significantly worsen drought conditions by hastening evaporation of water vapour.
Many plant species, such as those in the family Cactaceae (or cacti), have drought tolerance adaptations like reduced leaf area and waxy cuticles to enhance their ability to tolerate drought. Some others survive dry periods as buried seeds. Semi-permanent drought produces arid biomes such as deserts and grasslands.
Prolonged droughts have caused mass migrations and humanitarian crisis. Most arid ecosystems have inherently low productivity. The most prolonged drought ever in the world in recorded history occurred in the Atacama Desert in Chile 400 years ago .
The World Day to Combat Desertification and Drought is a United Nations observance each June 17. Its purpose is to raise awareness of the presence of desertification and drought, highlighting methods of preventing desertification and recovering from drought. Each year's global celebration has a unique, novel emphasis that had not been developed previously.
This day was proclaimed by the United Nations General Assembly resolution on January 30, 1995, after the day when United Nations Convention to Combat Desertification is drafted.
The 2030 Agenda for Sustainable Development declares that “we are determined to protect the planet from degradation, including through sustainable consumption and production, sustainably managing its natural resources and taking urgent action on climate change, so that it can support the needs of the present and future generations”.