Dryland expansion causes widespread water scarcity and biodiversity loss. Although the drying influence of global warming is well established, the role of existing drylands in their own expansion is relatively unknown. In this work, by tracking the air flowing over drylands, we show that the warming and drying of that air contributes to dryland expansion in the downwind direction. As they dry, drylands contribute less moisture and more heat to downwind humid regions, reducing precipitation and increasing atmospheric water demand, which ultimately causes their aridification. In ~40% of the land area that recently transitioned from a humid region into a dryland, self-expansion accounted for >50% of the observed aridification. Our results corroborate the urgent need for climate change mitigation measures in drylands to decelerate their own expansion.

中文翻译：

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陆地-大气反馈使旱地自我扩张


旱地扩张导致广泛的水资源短缺和生物多样性丧失。尽管全球变暖对干旱的影响已得到充分证实，但现有旱地在其自身扩张中的作用相对未知。在这项工作中，通过跟踪流经旱地的空气，我们发现空气的变暖和干燥有助于旱地顺风方向的扩张。当干燥时，旱地向顺风潮湿地区提供的水分减少，热量增加，降水减少，大气需水量增加，最终导致干旱。在最近从潮湿地区转变为干旱地区的约 40% 的土地面积中，自膨胀占观测到的干旱化的 >50%。我们的研究结果证实了旱地迫切需要采取减缓气候变化的措施，以减缓其自身的扩张。