Small temperature benefits provided by realistic afforestation efforts
Small temperature benefits provided by realistic afforestation efforts
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DOI：
10.1038/ngeo1182
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发表时间：
2011-08-01
影响因子：
18.3
通讯作者：
Montenegro, Alvaro
中科院分区：
文献类型：
--
作者：
Arora, Vivek K.;Montenegro, Alvaro
植树造林，将农田或边际土地转变为森林，可以固碳。因此，植树造林被联合国视为各国政府可采用的关键气候变化缓解战略之一(1)。然而，森林的反射率也低于农田，并且对入射太阳辐射的吸收比绿化地区更大。因此，植树造林会导致气候净变暖，特别是在高纬度地区(2-5)。在这里，我们使用综合地球系统模型来评估五种造林情景的气候变化减缓潜力，造林在50年的时间内逐步进行。在2081年至2100年期间，对目前农作物所占面积进行完全（100%）和部分（50%）植树造林分别导致气温升高约0.45和0:25摄氏度。与更现实的全球造林努力（只有不到 50% 的耕地转化）相关的温度效益预计会更小，这表明造林并不能替代减少温室气体排放。我们还表明，热带地区每单位造林面积的变暖减少量大约是寒带和北温带地区的三倍，这表明从气候角度来看，避免砍伐森林和继续在热带造林是有效的森林管理策略。
Afforestation, the conversion of croplands or marginal lands into forests, results in the sequestration of carbon. As a result, afforestation is considered one of the key climate-change mitigation strategies available to governments by the United Nations(1). However, forests are also less reflective than croplands, and the absorption of incoming solar radiation is greater over afforested areas. Afforestation can therefore result in net climate warming, particularly at high latitudes(2-5). Here, we use a comprehensive Earth system model to assess the climate-change mitigation potential of five afforestation scenarios, with afforestation carried out gradually over a 50-year period. Complete (100%) and partial (50%) afforestation of the area occupied at present by crops leads to a reduced warming of around 0.45 and 0 : 25 degrees C respectively, during the period 2081-2100. Temperature benefits associated with more realistic global afforestation efforts, where less than 50% of cropland is converted, are expected to be even smaller, indicating that afforestation is not a substitute for reduced greenhouse-gas emissions. We also show that warming reductions per unit afforested area are around three times higher in the tropics than in the boreal and northern temperate regions, suggesting that avoided deforestation and continued afforestation in the tropics are effective forestmanagement strategies from a climate perspective.