Distribution and Growth Drivers of Oases at a Global Scale

Abstract

The human‐environmental system in drylands is centered on oases. Despite its extent and socio‐ecological importance, understanding the dynamic changes of global oases and their human and environmental driving forces is imperative for sustainable development in drylands under global warming. Nevertheless, the dynamic changes of global oases and how they respond to the evolving environment are not well established. In this study, three criteria were summarized (i.e., existing in dryland climates, surrounded or partially surrounded by desert terrain, having a reliable source of freshwater and forming landscape units with higher vegetation coverage/productivity). A global oasis distribution map from 1995 to 2020 was generated using European Space Agency Climate Change Initiative Land Cover and GIMMS‐3G+ data (overall accuracy within a 95% confidence interval is 0.85 ± 0.01) based on overlay analysis and visual interpretation. In addition, we used geographic and temporal weighted regression methods to evaluate the potential macro‐level elements affecting both global and local oasis growth. The result showed that the global oases area in 2020 occupied an area of 191.91 Mha, and most oases existed in Asia (77.3%). The global oases area has significantly increased from 1995 to 2020 (+8.65 Mha). However, about 13.43 Mha of the global oases are desertified, indicating a high risk of desertification. Water resources, contributing 51.36% to the total driver's contribution, are key to the global oasis expansion. In the context of climate (climate variability and climate change), this research highlights the need for improved holistic water resource management for long‐term global oasis growth, particularly in developing countries where the oases' development is threatened by water scarcity and desertification.