A recent report from the United Nations shows that an area almost a third larger than India has turned from humid conditions to permanently dry – or arid – in the past three decades. Excluding Antarctica, drylands now make up 40.6% of all land on Earth, a +3% increase compared to the earlier 30-year period. Meanwhile, some 77.6% of the planet’s land experienced a drier climate within the same timeframe.
The Science-Policy Interface, the group of scientists for the UN Convention to Combat Desertification (UNCCD) that authored the new report, says rising temperatures are altering the water cycle in many areas of the world, increasing the risk of droughts. Drought-induced water scarcity, land degradation, and desertification increase soil aridity, resulting in less fertile land, crop and plant productivity losses, biodiversity declines, and ecosystem degradation.
Aridity – defined as the long-term dryness of a region, which causes low water content in the soil – is considered the world’s single-largest driver of agricultural systems degradation. Arid land is also more prone to sand and dust storms, wildfires, and poor health, making it increasingly inhospitable for humans and most animal and plant species, according to the authors.
Ibrahim Thiaw, executive secretary of the UNCCD, says aridity represents a “permanent, unrelenting transformation.” As Thiaw explains, droughts end and the affected area eventually recovers. By contrast, when an area’s climate becomes drier, it loses the ability to return to previous “normal” conditions. “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,” Thiaw said.
According to the study, more than three-quarters of all land on Earth experienced a drier climate during the three decades leading up to 2020, compared to the previous 30-year period, and global drylands expanded by about 1.66 million square miles—an area equal to half the size of the continent of Australia/Oceania—to cover more than 40% of all global land.
Hotspots showing significant dryland expansion include the western United States, north-eastern Brazil, north-western Argentina, the entire Mediterranean region, the northern side of the Black Sea, and large parts of Mongolia, north-eastern China, and south-eastern Australia. Future expansion is expected to be worse in sub-Saharan and North Africa, the Middle East, and South Asia.
Crop production in increasingly arid areas will obviously face new risks. The study projects a climate-change related increase in global arid area of +3.9% by 2040 will mean losses of about -20 million tons of corn, -19 million tons of rice, -8 million tons of soybeans, and -21 million tons of wheat. The worst affected areas will see the greatest losses. In sub-Saharan Africa, for example, between 17% and 22% of current crop production could be lost by mid-century due to the impacts of increasing aridity and temperatures.
The authors note that aridity’s impacts on livestock has not been well researched, with most focused on the effects of droughts. Still, the study says climate aridification may also affect livestock production in the future by altering the quantity and quality of forage and available water, increasing heat stress and creating other climate conditions to which a region’s livestock species may not be currently adapted. The full report is available HERE.