Surface albedo greatly affects how much energy the Earth absorbs. Intensive human activities and accelerated climate change have altered surface albedo across spatial and temporal scales^1,2,3, yet assessments of the effects of land use or land cover (LULC) and snow variations on land surface albedo are scarce at the global scale. As a result, the global land surface albedo dynamics over recent decades and their corresponding radiative forcing to the climate system remain poorly understood^4,5,6,7,8,9. Here we quantify the individual and combined effects of snow cover dynamics, LULC conversions and non-conversion regions on albedo variations during 2001–2020 and estimate their induced radiative forcing. We show that the negative radiative forcing induced by the global land surface albedo change was −0.142 (−0.158, −0.114) W m⁻² over the past two decades. The global snow-free land surface albedo increased by 2.2% (P < 0.001), with a negative radiative forcing of −0.164 (−0.186, −0.138) W m⁻² (P < 0.001). The magnitude of this negative forcing is sevenfold larger than the positive forcing induced by snow dynamics, and equivalent to 59.9% of that caused by CO₂ emissions from 2011 to 2019¹⁰. The global radiative forcing due to albedo changes in LULC non-conversion regions is 3.9 to 8.1 times greater than that from LULC conversions. The radiative forcing induced by albedo changes highlights the important role of land surface dynamics in modulating global warming.

表面反照率极大地影响了地球吸收的能量。密集的人类活动和加速的气候变化在空间和时间尺度上改变了地表反照率 ^1,2,3，但在全球范围内，对土地利用或土地覆盖 （LULC） 和雪变化对地表反照率影响的评估很少。因此，近几十年来全球地表反照率动力学及其对气候系统的相应辐射强迫仍然知之甚少 ^4,5,6,7,8,9。在这里，我们量化了 2001-2020 年期间积雪动力学、LULC 转换和非转换区域对反照率变化的单独和综合影响，并估计它们诱导的辐射强迫。我们表明，在过去二十年中，全球地表反照率变化引起的负辐射强迫为 -0.142 （-0.158， -0.114） W ^m-2。全球无雪地表反照率增加了 2.2% （P < 0.001），负辐射强迫为 -0.164 （-0.186， -0.138） W ^m-2 （P < 0.001）。这种负强迫的幅度是雪动力学引起的正强迫的七倍，相当于 2011 年至 2019 年 CO₂ 排放造成的正强迫的 59.9%¹⁰。由于 LULC 非转换区域中的反照率变化引起的全局辐射强迫是 LULC 转换的 3.9 到 8.1 倍。反照率变化引起的辐射强迫突出了地表动力学在调节全球变暖中的重要作用。