It has been well acknowledged that a continuous increase in atmospheric carbon dioxide (CO₂) concentration will lead to climate warming. Numerous experiments have found that increased precipitation could promote soil CO₂ emissions into the atmosphere, but there is great uncertainty in the magnitude of increased precipitation of this feedback. Here, we assessed the influences of different durations and magnitudes of increased precipitation on soil CO₂ efflux across biomes through a meta-analysis. Humid (extremely wet, moderately wet, and slightly wet), temperate, and arid (slight drought, moderate drought and extreme drought) areas were classified according to the Palmer drought severity index (PDSI). Overall, the average experimentally applied precipitation increases of 31.81%, 19.14% and 37.68% significantly stimulated soil CO₂ efflux by 12.74%, 13.10% and 14.71%, respectively for experiments from all areas, humid areas, and arid areas. No significant effects were found for temperate areas. Increased precipitation stimulated large soil CO₂ efflux in extreme drought areas (PDSI > −3) by 38.09%. Moreover, soil CO₂ efflux increased with increasing precipitation intensity but decreased with increasing precipitation duration regardless of the area with different PDSIs. Our results highlight the positive feedback between soil CO₂ efflux and increased precipitation in both humid and arid terrestrial ecosystems, which improves our understanding in possible climate change effects on the global carbon cycle. Further efforts should assess the differential effects of various durations and magnitudes of increased precipitation in ecosystems with different wetness conditions.

众所周知，大气中二氧化碳（CO ₂）浓度的持续增加将导致气候变暖。许多实验已经发现，增加的降水量可以促进土壤CO ₂排放到大气中，但是这种反馈增加的降水量存在很大的不确定性。在这里，我们评估了不同持续时间和增加降水量对土壤CO _2的影响通过荟萃分析跨生物群系流出。根据帕尔默干旱严重性指数（PDSI）对潮湿（极湿，中湿和微湿），温带和干旱（轻度干旱，中度干旱和极端干旱）地区进行了分类。总体而言，在所有地区，潮湿地区和干旱地区进行的实验中，平均实验应用的降水增加分别为31.81％，19.14％和37.68％，分别显着刺激了土壤CO ₂排放量分别为12.74％，13.10％和14.71％。在温带地区未发现明显影响。降水增加促使极端干旱地区（PDSI> -3）的大量土壤CO ₂排放增加38.09％。此外，土壤CO ₂流出量随降水强度的增加而增加，但随降水持续时间的增加而减小，而与不同PDSI的面积无关。我们的研究结果强调了土壤CO ₂流出与湿润和干旱陆地生态系统中降水增加之间的正反馈，这增进了我们对气候变化对全球碳循环可能影响的理解。进一步的努力应评估在不同湿度条件下生态系统中各种持续时间和降水增加幅度的不同影响。