Aridity: The ‘existential crisis’ redefining life on Earth | Five billion people could be affected by 2100
Riyadh, Saudi Arabia – Even as dramatic water-related disasters such as floods and storms intensified in some parts of the world, more than three-quarters of Earth’s land became permanently drier in recent decades, UN scientists warned today in a stark new analysis.
Some 77.6% of Earth’s land experienced drier conditions during the three decades leading up to 2020 compared to the previous 30-year period, according to the landmark report from the UN Convention to Combat Desertification (UNCCD).
Over the same period, drylands expanded by about 4.3 million km2 – an area nearly a third larger than India, the world’s 7th largest country – and now cover 40.6% of all land on Earth (excluding Antarctica).
In recent decades some 7.6% of global lands – an area larger than Canada – were pushed across aridity thresholds (i.e. from non-drylands to drylands, or from less arid dryland classes to more arid classes).
Most of these areas have transitioned from humid landscapes to drylands, with dire implications for agriculture, ecosystems, and the people living there.
And the research warns that, if the world fails to curb greenhouse gas emissions, another 3% of the world’s humid areas will become drylands by the end of this century.
In high greenhouse gas emissions scenarios, expanding drylands are forecast across the Midwestern United States, central Mexico, northern Venezuela, north-eastern Brazil, south-eastern Argentina, the entire Mediterranean Region, the Black Sea coast, large parts of southern Africa, and southern Australia.
The report, The Global Threat of Drying Lands: Regional and global aridity trends and future projections, was launched at the 16th conference of UNCCD’s nearly 200 Parties in Riyadh, Saudi Arabia (COP16), the largest UN land conference to date, and the first UNCCD COP to be held in the Middle East, a region profoundly affected by impacts from aridity.
“This analysis finally dispels an uncertainty that has long surrounded global drying trends,” says Ibrahim Thiaw, UNCCD Executive Secretary. “For the first time, the aridity crisis has been documented with scientific clarity, revealing an existential threat affecting billions around the globe.”
“Unlike droughts – temporary periods of low rainfall – aridity represents a permanent, unrelenting transformation,” he adds. “Droughts end. When an area’s climate becomes drier, however, the ability to return to previous conditions is lost. The drier climates now affecting vast lands across the globe will not return to how they were and this change is redefining life on Earth.”
The report by UNCCD Science-Policy Interface (SPI) – the UN body for assessing the science of land degradation and drought – points to human-caused climate change as the primary driver of this shift. Greenhouse gas emissions from electricity generation, transport, industry and land use changes warm the planet and other human activities warm the planet and affect rainfall, evaporation and plant life, creating the conditions that increase aridity.
Global aridity index (AI) data track these conditions and reveal widespread change over the decades.
Aridification hotspots
Areas particularly hard-hit by the drying trend include almost all of Europe (95.9% of its land), parts of the western United States, Brazil, parts of Asia (notably eastern Asia), and central Africa.
- Parts of the Western United States and Brazil: Significant drying trends, with water scarcity and wildfires becoming perennial hazards.
- Mediterranean and Southern Europe: Once considered agricultural breadbaskets, these areas face a stark future as semi-arid conditions expand.
- Central Africa and parts of Asia: Biologically megadiverse areas are experiencing ecosystem degradation and desertification, endangering countless species.
By contrast, less than a quarter of the planet’s land (22.4%) experienced wetter conditions, with areas in the central United States, Angola’s Atlantic coast, and parts of Southeast Asia showing some gains in moisture.
The overarching trend, however, is clear: drylands are expanding, pushing ecosystems and societies to suffer from aridity’s life-threatening impacts.
The report names South Sudan and Tanzania as nations with the largest percentage of land transitioning to drylands, and China as the country experiencing the largest total area shifting from non-drylands into drylands.
For the 2.3 billion people – well over 25% of the world’s population – living in the expanding drylands, this new normal requires lasting, adaptive solutions. Aridity-related land degradation, known as desertification, represents a dire threat to human well-being and ecological stability.
And as the planet continues to warm, report projections in the worst-case scenario suggest up to 5 billion people could live in drylands by the century’s end, grappling with depleted soils, dwindling water resources, and the diminishment or collapse of once-thriving ecosystems.
Forced migration is one of aridity’s most visible consequences. As land becomes uninhabitable, families and entire communities facing water scarcity and agricultural collapse often have no choice but to abandon their homes, leading to social and political challenges worldwide. From the Middle East to Africa and South Asia, millions are already on the move – a trend set to intensify in coming decades.
Aridity’s devastating impact
The effects of rising aridity are cascading and multifaceted, touching nearly every aspect of life and society, the report says.
It warns that one fifth of all land could experience abrupt ecosystem transformations from rising aridity by the end of the century, causing dramatic shifts (such as forests becoming grasslands and other changes) and leading to extinctions among many of the world’s plants, animals and other life.
- Aridity is considered the world’s largest single driver behind the degradation of agricultural systems, affecting 40% of Earth’s arable lands
- Rising aridity has been blamed for a 12% decline in gross domestic product (GDP) recorded for African countries between 1990–2015
- More than two thirds of all land on the planet (excluding Greenland and Antarctica) is projected to store less water by the end of the century, if greenhouse gas emissions continue to rise even modestly
- Aridity is considered one of the world’s five most important causes of land degradation (along with land erosion, salinization, organic carbon loss and vegetation degradation)
- Rising aridity in the Middle East has been linked to the region’s more frequent and larger sand and dust storms
- Increasing aridity is expected to play a role in larger and more intense wildfires in the climate-altered future – not least because of its impacts on tree deaths in semi-arid forests and the consequent growing availability of dry biomass for burning
- Rising aridity’s impacts on poverty, water scarcity, land degradation and insufficient food production have been linked to increasing rates of sickness and death globally – especially among children and women
- Rising aridity and drought play a key role in increasing human migration around the world – particularly in the hyper-arid and arid areas of southern Europe, the Middle East and North Africa and southern Asia.
Report marks a turning point
For years, documenting the rise of aridity proved a challenge, the report states. Its long-term nature and the intricate interplay of factors such as rainfall, evaporation, and plant transpiration made analysis difficult. Early studies produced conflicting results, often muddied by scientific caution.
The new report marks a turning point, leveraging advanced climate models and standardized methodologies to deliver a definitive assessment of global drying trends, confirming the inexorable rise of aridity, while providing critical insights into its underlying drivers and potential future trajectory. Continue to read here.
Article Source:
Press Release/Material by UN Convention to Combat Desertification
Featured image credit: Mike van Schoonderwalt | Pexels
