Forestation of the vast global drylands has been considered a promising climate change mitigation strategy. However, its actual climatic benefits are uncertain because the forests’ reduced albedo can produce large warming effects. Using high-resolution spatial analysis of global drylands, we found 448 million hectares suitable for afforestation. This area’s carbon sequestration potential until 2100 is 32.3 billion tons of carbon (Gt C), but 22.6 Gt C of that is required to balance albedo effects. The net carbon equivalent would offset ~1% of projected medium-emissions and business-as-usual scenarios over the same period. Focusing forestation only on areas with net cooling effects would use half the area and double the emissions offset. Although such smart forestation is clearly important, its limited climatic benefits reinforce the need to reduce emissions rapidly.

中文翻译：

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通过在广阔的旱地地区造林来减缓气候变化的潜力有限

在广阔的全球旱地造林被认为是一种有前景的减缓气候变化的战略。然而，它的实际气候效益是不确定的，因为森林减少的反照率会产生巨大的变暖效应。通过对全球旱地的高分辨率空间分析，我们发现 4.48 亿公顷适合植树造林。该地区到 2100 年的碳封存潜力为 323 亿吨碳 (Gt C)，但平衡反照率效应需要 22.6 Gt C。净碳当量将抵消同期预计中等排放和一切照旧情景的约 1%。仅将造林重点放在具有净降温效果的地区将使用一半的面积并将排放抵消增加一倍。尽管这种智能造林显然很重要，