Study: Arid Regions Increasing Worldwide
Climate Change is the main driver, but agriculture also plays a major role.
Aridity on our planet is taking on alarming dimensions. More than three quarters of the earth’s land area has become dryer in the past three decades. This is shown by a new scientific study from the United Nations Convention to Combat Desertification (UNCCD). According to the analysis, 77,6 percent of the global land area showed an increased tendency towards aridity in the three decades until 2020. In Europe, the figure is as high as 96 percent of the land - but affects far fewer people than in Asia or Africa.
A tendency towards aridity does not yet signify serious aridity. Until now, 40,6 percent of the global land area (excluding Antarctica) was classified as dryland. But those drylands are increasing as well. As shown in the graphs in the middle and on the right, in the two periods covered the percentage of drylands has been growing in the various regions and globally – although at varying rates. Here too, the increase is remarkable. It comprises 4,3 million square kilometers worldwide. This means more drylands covering an area equivalent to a third of the area of India between 1990 and 2020.
The consequences for agriculture, ecosystems and of course for people living in the drylands are serious. 30,9 percent or 2,3 billion people lived in drylands in 2020, almost a third of the world population – compared to about a fifth or 1,2 billion people 30 years earlier. Most people living in drylands are in Asia (1,3 billion) and Africa (620 million). The most densely populated drylands are in California, Egypt, Eastern and Western Pakistan as well as in large parts of India and in northeast China.
To quantify the extent of aridity, UNCCD uses the Aridity Index (AI). Drylands comprise areas that are classified as “hyperarid, arid, semi-arid, and dry subhumid”. A fifth category in the Aridity Index is „humid“. Aridity is a climatic condition characterized by a substantial lack of humidity. This leads to limited water availability in certain regions.
Aridity refers to long term climatic conditions and is distinct from short term drought events as well as land degradation, which is defined as a reduction or loss of biological or economic productivity as well as of complexity in rain fed agriculture, irrigation agriculture, pastureland, forests and forested regions. Desertification, on the other hand, designates soil degradation in drylands that are not deserts. It can be caused by various factors, including climate change as well as human influence.
Half the World Population in Drylands?
The main driver of increasing aridity according to the UNCCD study is climate change. But maladapted agricultural practices, excessive water use, soil erosion and destruction of natural vegetation also play a role. The number of people living in drylands could well increase to five billion by the end of the century. One of the most visible consequences is likely to be that people would be forced to migrate, leading to increasing challenges for less arid parts of a country and for neighboring countries. Additional projected consequences could be: loss of biodiversity, reduction in soil quality, increase in wildfires and in sand and dust storms, among others. The tendency towards more aridity, however, does not mean that in the foresseable future all land areas will be arid. Large parts of the land surface continue to be classiefied as "humid" by the UNCCD study.
The study makes recommendations on dealing with aridity aimed at mitigation and adaptation. Among the recommendations are a strengthening of aridity monitoring, improvements in land usage practices, higher investment in water efficiency, strengthening the resilience of affected communities as well as the development of an international framework and stronger international cooperation.
All views expressed in the Welternährung are those of the authors and do not necessarily reflect the view or policies of the editorial board or of Welthungerhilfe.
