Drylands cover almost half of the world’s land surface, encompassing deserts, shrublands, grasslands, and savanna woodlands. These regions are characterized by water scarcity, which has profound impacts on natural ecosystems and human activities such as agriculture, forestry, and livestock production. While the role of climate change and land management practices in dryland expansion has been well-documented, a new study sheds light on an alarming trend: drylands are accelerating their own spread.
Climate scientists from the University of Bristol, Ghent University, Cardiff University, and ETH Zurich collaborated on the research, which revealed that drylands are exacerbating atmospheric drying, resulting in increased water loss through evaporation. This process is driving the global expansion of drylands, transforming previously humid regions into arid environments. The study quantified the self-expansion of drylands by analyzing sources of precipitation and heat over newly expanded areas, showing that existing drylands contribute significantly to their own proliferation.
By tracking air movements over the past four decades, researchers found that drying soils in existing drylands release less moisture and more heat into the atmosphere, leading to reduced rainfall and increased atmospheric water demand in downwind humid regions. This phenomenon has been identified as the primary driver of dryland spread in regions such as Australia and Eurasia. As the world moves towards a warmer and potentially drier future, the self-propagation of drylands poses significant risks to human livelihoods, ecosystems, and socio-economic stability globally.
The study also highlights the regions most vulnerable to further dryland expansion, emphasizing the urgent need for climate change mitigation and sustainable land management practices. By quantifying the impact of distant vegetation responses on dryland expansion, the research underscores the importance of coordinated ecosystem conservation efforts in existing drylands. The team is currently working on developing land-based adaptation strategies to prevent drought and heat propagation, recognizing the critical need for proactive measures to address the accelerating spread of drylands.
The acceleration of dryland expansion is a concerning trend with far-reaching implications for both natural ecosystems and human communities. By understanding the underlying factors driving this phenomenon, researchers are better equipped to develop targeted strategies for mitigating its impacts and promoting sustainable land management practices. Addressing the challenges posed by dryland self-expansion requires a coordinated global effort to combat climate change and protect vulnerable regions from the spread of arid environments.