Luo Hao, Quaas Johannes, Han Yong
Advanced Science & Technology of Space and Atmospheric Physics Group (ASAG), School of Atmospheric Sciences, Sun Yat-sen University, 519082, Zhuhai, China.
Leipzig Institute for Meteorology, Leipzig University, 04103, Leipzig, Germany.
Nat Commun. 2024 Aug 26;15(1):7345. doi: 10.1038/s41467-024-51783-y.
Biophysical processes of forests affect climate through the regulation of surface water and heat fluxes, which leads to further effects through the adjustment of clouds and water cycles. These indirect biophysical effects of forests on clouds and their radiative forcing are poorly understood but highly relevant in the context of large-scale deforestation or afforestation, respectively. Here, we provide evidence for local decreases in global low-level clouds and tropical high-level clouds from deforestation through both idealized deforestation simulations with climate models and from observations-driven reanalysis using space-for-time substitution. The decreased cloud cover can be explained by alterations in surface turbulent heat flux, which diminishes uplift and moisture to varying extents. Deforestation-induced reduction in cloud cover warms the climate, partially counteracting the cooling effects of increased surface albedo. The findings from idealized deforestation experiments and space-for-time substitution exhibit disparities, with global average offsets of, respectively, approximately 44% and 26%, suggesting the necessity for further constraints.
森林的生物物理过程通过调节地表水和热通量影响气候，进而通过调节云和水循环产生进一步影响。森林对云和辐射强迫的这些间接生物物理效应了解甚少，但分别在大规模毁林或造林的背景下具有高度相关性。在这里，我们通过使用气候模型进行理想化毁林模拟以及利用时空替代的观测驱动再分析，提供了毁林导致全球低云量和热带高云量局部减少的证据。云量减少可以用地表湍流通量的变化来解释，地表湍流通量在不同程度上减少了上升气流和水汽。毁林导致的云量减少使气候变暖，部分抵消了地表反照率增加的冷却效应。理想化毁林实验和时空替代的结果存在差异，全球平均抵消率分别约为44%和26%，这表明需要进一步的约束。
