Rainfall events are globally becoming less frequent but more intense under a changing climate, thereby shifting climatic conditions for terrestrial vegetation independent of annual rainfall totals^1,2,3. However, it remains uncertain how changes in daily rainfall variability are affecting global vegetation photosynthesis and growth^{3,4,5,6,7,8,9,10,11,12,13,14,15,16,17}. Here we use several satellite-based vegetation indices and field observations indicative of photosynthesis and growth, and find that global annual-scale vegetation indices are sensitive to the daily frequency and intensity of rainfall, independent of the total amount of rainfall per year. Specifically, we find that satellite-based vegetation indices are sensitive to daily rainfall variability across 42 per cent of the vegetated land surfaces. On average, the sensitivity of vegetation to daily rainfall variability is almost as large (95 per cent) as the sensitivity of vegetation to annual rainfall totals. Moreover, we find that wet-day frequency and intensity are projected to change with similar magnitudes and spatial extents as annual rainfall changes. Overall, our findings suggest that daily rainfall variability and its trends are affecting global vegetation photosynthesis, with potential implications for the carbon cycle and food security.

在气候变化的情况下，全球降雨事件的频率越来越低，但强度越来越大，因此陆地植被的气候条件发生了变化，与年总降雨量无关^1,2,3。然而，仍不确定每日降雨变化如何影响全球植被光合作用和生长^{3,4,5,6,7,8,9,10,11,12,13,14,15,16,17}。在这里，我们使用了几个基于卫星的植被指数和实地观测，表明光合作用和生长，发现全球年尺度植被指数对每日降雨频率和强度很敏感，与每年的总降雨量无关。具体来说，我们发现基于卫星的植被指数对 42% 的植被陆地表面的每日降雨变化很敏感。平均而言，植被对日降雨变化的敏感性几乎与植被对年总降雨量的敏感性一样大（95%）。此外，我们发现，预计雨日频率和强度的变化幅度和空间范围与年降雨量变化相似。总体而言，我们的研究结果表明，每日降雨变化及其趋势正在影响全球植被光合作用，对碳循环和粮食安全有潜在影响。