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Desert greening through planting or irrigation is a potential approach to mitigate desertification and climate warming, but its influence on regional climate is unclear due to scarcity of observations. "Desert blooms," which are natural phenomena usually associated with the El Nino-Southern Oscillation, regularly occur in the world’s driest desert, the Atacama Desert. This sudden conversion of land cover likely has a large impact on regional climate through alteration of local energy budgets and provides a unique opportunity to study the potential climatic and environmental consequences of desert greening. Here we evaluated the land surface effects of blooms in the Atacama Desert using vegetation and climate data acquired from remote sensing. The rapid vegetation growth during blooms led to an increase in evapotranspiration and a decrease in albedo. These two processes caused a 0.31 degrees C +/- 0.05 degrees C decrease in daytime land surface temperature. During nighttime, we observed a 0.02 degrees C +/- 0.02 degrees C increase in land surface temperature due to enhanced heat capacity associated with blooms. This asymmetric diurnal variation in land surface temperature produced a net decrease in daily land surface temperature of 0.29 degrees C +/- 0.07 degrees C. Our observations demonstrate the potential benefits of desert blooms on local climate. Results from this study also provide new evidence for plausible climate consequences expected from local "desert greening" strategies.

Plain Language Summary Desert areas have expanded globally over the past century and are projected to increase continually throughout the current century owing to global warming. " Desert greening" by plantation or irrigation has been proposed as a method to decrease desertification, mitigate climate warming through increased carbon sequestration, and produce food and biofuel. However, the actual impact of desert greening on regional climate is still poorly understood due to scarcity of observational studies. "Desert bloom" is a natural phenomenon that happened in the world’s driest Atacama Desert. Relying on remote sensing observations, we find that this desert bloom-caused natural greening has obvious cooling effect on land surface. This finding has important implications for the design of desert greening strategies.