PBL Netherlands Environmental Assessment Agency, The Hague, The Netherlands.
Copernicus Institute for Sustainable Development, Utrecht University, Utrecht, The Netherlands.
Glob Chang Biol. 2020 Mar;26(3):1576-1591. doi: 10.1111/gcb.14887. Epub 2019 Nov 29.
Afforestation is considered a cost-effective and readily available climate change mitigation option. In recent studies afforestation is presented as a major solution to limit climate change. However, estimates of afforestation potential vary widely. Moreover, the risks in global mitigation policy and the negative trade-offs with food security are often not considered. Here we present a new approach to assess the economic potential of afforestation with the IMAGE 3.0 integrated assessment model framework. In addition, we discuss the role of afforestation in mitigation pathways and the effects of afforestation on the food system under increasingly ambitious climate targets. We show that afforestation has a mitigation potential of 4.9 GtCO /year at 200 US$/tCO in 2050 leading to large-scale application in an SSP2 scenario aiming for 2°C (410 GtCO cumulative up to 2100). Afforestation reduces the overall costs of mitigation policy. However, it may lead to lower mitigation ambition and lock-in situations in other sectors. Moreover, it bears risks to implementation and permanence as the negative emissions are increasingly located in regions with high investment risks and weak governance, for example in Sub-Saharan Africa. Afforestation also requires large amounts of land (up to 1,100 Mha) leading to large reductions in agricultural land. The increased competition for land could lead to higher food prices and an increased population at risk of hunger. Our results confirm that afforestation has substantial potential for mitigation. At the same time, we highlight that major risks and trade-offs are involved. Pathways aiming to limit climate change to 2°C or even 1.5°C need to minimize these risks and trade-offs in order to achieve mitigation sustainably.
造林被认为是一种具有成本效益且易于实施的气候变化缓解措施。在最近的研究中，造林被提出作为限制气候变化的主要解决方案。然而，造林潜力的估计差异很大。此外，全球缓解政策的风险以及与粮食安全的负面权衡往往没有得到考虑。在这里，我们提出了一种新的方法，利用 IMAGE 3.0 综合评估模型框架来评估造林的经济潜力。此外，我们还讨论了造林在缓解途径中的作用，以及在越来越雄心勃勃的气候目标下造林对粮食系统的影响。我们表明，在 2050 年，以 200 美元/吨二氧化碳的价格，造林具有每年 4.9 吉吨二氧化碳的减排潜力，在 SSP2 情景下将大规模应用，目标是 2°C（到 2100 年累计 410 吉吨二氧化碳）。造林可以降低缓解政策的总成本。然而，它可能导致其他部门的减排雄心降低和锁定情况。此外，由于负排放越来越集中在投资风险高和治理薄弱的地区，例如撒哈拉以南非洲，因此造林存在实施和永久性的风险。造林还需要大量土地（高达 1100 万公顷），导致农业用地大量减少。对土地的竞争加剧可能导致粮食价格上涨，更多人面临饥饿风险。我们的结果证实，造林具有相当大的减排潜力。同时，我们强调存在重大风险和权衡。为了实现可持续缓解，旨在将气候变化限制在 2°C 甚至 1.5°C 的途径需要最小化这些风险和权衡。
