Examining Changes in Drought and Aridification Characteristics for the Drylands of Northeast Brazil: A Review.

This review examines the changing characteristics of drought and aridification in the drylands of Northeast Brazil (NEB), a region marked by significant vulnerability to water scarcity and climate extremes. Globally, drylands make up a substantial portion of developing countries, and South America's drylands cover roughly 31% of the continent, with NEB representing one of the most densely populated semi-arid regions. The review distinguishes between aridity, a persistent climatic state defined by low precipitation and high evaporative demand, and drought, an episodic event characterized by prolonged below-normal water availability. Both phenomena drive agroecological patterns, affecting plant physiology, structure, diversity, and ecosystem functioning. Recent climate shifts and unsustainable human activities are pushing the boundaries of arid and semi-arid zones beyond their traditional limits, raising concerns about the expansion of desertification and intensified water scarcity. Drought events in Brazil have increased in frequency and severity, especially in NEB, with impacts exacerbated by concurrent climate stressors such as heatwaves. Severe droughts have occurred across multiple regions-including the Pantanal, Amazonia, Southeast Brazil, and the La Plata basin-and are often linked to El Niño and La Niña cycles, threatening food, water, and energy security. The spatial and temporal variability of drought complicates monitoring and management, emphasizing the need for improved assessment and predictive tools. Vegetation responses in NEB indicate worsening water limitation, with consequences for agroecosystem resilience and productivity. This review highlights the urgent need for integrated strategies to address both drought and aridification in the NEB, given their expanding influence under climate change and their profound effects on societal and agroecological systems.