造林增汇是实现碳中和的成本有效途径吗?——以西北地区为例

Is afforestation for carbon sinks a cost-effective way to achieve carbon neutrality?Take Northwest China as an example

造林增汇是减缓气候变化的重要方式,但其碳中和效果背后的成本有效性不可忽视,这对西北干旱半干旱地区尤为重要。基于西北地区GIS平台数据,构建地理—经济—生态三维整合分析框架,采用环境因子叠加模型和土地利用动态优化模型,从自然可行性和经济可行性两个角度识别了西北地区边际可造林区域,采用Richards生长方程预测了造林碳汇潜力,以此为基础拟合了碳汇供给曲线,并对西北地区造林增汇的成本有效性进行了评价。结果表明:(1)西北地区满足自然和经济双重可行性的造林土地面积为102.71万hm^(2),仅占自然可行造林土地面积的20.56%。其中以草地和未利用地为主,主要分布在青海和甘肃两省。(2)西北地区造林的碳汇潜力为9.37 Mt CO_(2)/年,到2060年能够为该地区碳中和目标提供约9.70%~15.06%的贡献,不可忽视。(3)西北地区造林增汇的平均成本为948.81元/t CO_(2),相比于能源碳减排路径,整体上不具有成本有效性。且在迫切应对气候变化情景下,西北地区造林增汇的成本有效性更弱。据此,提出强化造林增汇对碳中和贡献的政策建议。

Afforestation is an important way to mitigate climate change,but its cost effectiveness cannot be ignored,which is especially important for the arid and semi-arid regions in Northwest China.To evaluate the cost effectiveness of afforestation for carbon sink in Northwest China,this paper constructed a three-dimensional integrated geographyeconomy-ecology analysis framework.The marginal afforestation areas in Northwest China was identified based on the superposition model of environmental factors and the dynamic optimization model of land use.The carbon sink potential by afforestation was predicted using the Richards growth equation,based on which the carbon sink supply curve was fitted.The cost effectiveness of afforestation for carbon sink in Northwest China was also analyzed.The results showed that:(1)The afforestation area that satisfies both natural and economic feasibility is 1027100 hm^(2) in Northwest China,accounting for about 20.56% of natural afforestation.Among them,grassland and unused land were dominant,and suitable afforestation areas were mainly distributed in Qinghai and Gansu provinces.(2)The carbon sink potential of afforestation in Northwest China is 9.37 million tons CO_(2) per year,and by 2060,afforestation will contribute approximately 9.70%-15.06% to the carbon neutrality target of this region,which cannot be ignored.(3)The average cost of afforestation for carbon sink in Northwest China was 948.81 yuan/t CO_(2),which was not cost-effective overall compared with the carbon emission reduction cost of thermal power.And in scenarios where climate change needs to be addressed urgently,the afforestation for carbon sinks in Northwest China will become even less cost effective.Accordingly,policy recommendations were proposed to improve the contribution of afforestation for achieving carbon neutrality.