Australian Rivers Institute, Griffith University, Nathan, Qld, Australia.
Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Qld, Australia.
Glob Chang Biol. 2021 Jun;27(12):2856-2866. doi: 10.1111/gcb.15571. Epub 2021 Mar 17.
Mangroves have among the highest carbon densities of any tropical forest. These 'blue carbon' ecosystems can store large amounts of carbon for long periods, and their protection reduces greenhouse gas emissions and supports climate change mitigation. Incorporating mangroves into Nationally Determined Contributions to the Paris Agreement and their valuation on carbon markets requires predicting how the management of different land-uses can prevent future greenhouse gas emissions and increase CO sequestration. We integrated comprehensive global datasets for carbon stocks, mangrove distribution, deforestation rates, and land-use change drivers into a predictive model of mangrove carbon emissions. We project emissions and foregone soil carbon sequestration potential under 'business as usual' rates of mangrove loss. Emissions from mangrove loss could reach 2391 Tg CO by the end of the century, or 3392 Tg CO when considering foregone soil carbon sequestration. The highest emissions were predicted in southeast and south Asia (West Coral Triangle, Sunda Shelf, and the Bay of Bengal) due to conversion to aquaculture or agriculture, followed by the Caribbean (Tropical Northwest Atlantic) due to clearing and erosion, and the Andaman coast (West Myanmar) and north Brazil due to erosion. Together, these six regions accounted for 90% of the total potential CO future emissions. Mangrove loss has been slowing, and global emissions could be more than halved if reduced loss rates remain in the future. Notably, the location of global emission hotspots was consistent with every dataset used to calculate deforestation rates or with alternative assumptions about carbon storage and emissions. Our results indicate the regions in need of policy actions to address emissions arising from mangrove loss and the drivers that could be managed to prevent them.
红树林的碳密度在所有热带森林中是最高的。这些“蓝色碳”生态系统可以长期储存大量的碳,保护它们可以减少温室气体排放,支持气候变化减缓。将红树林纳入国家对《巴黎协定》的自主贡献,并在碳市场上对其进行估值,需要预测不同土地利用方式的管理如何能够防止未来的温室气体排放并增加 CO2 的固存。我们将碳储量、红树林分布、森林砍伐率和土地利用变化驱动因素等综合全球数据集纳入红树林碳排放量的预测模型。我们预测了在红树林损失的“照常营业”速度下的排放量和土壤碳封存的潜在损失。到本世纪末,红树林损失造成的排放量可能达到 2391 百万吨 CO2,若考虑土壤碳封存的潜在损失,则排放量可能达到 3392 百万吨 CO2。由于转换为水产养殖或农业,预计排放和潜在土壤碳封存损失最大的地区在东南亚和南亚(西珊瑚三角区、巽他陆架和孟加拉湾),其次是加勒比地区(热带西北大西洋),原因是清理和侵蚀,以及安达曼海岸(缅甸西部)和北巴西,原因是侵蚀。这六个地区加起来占未来 CO2 总排放量的 90%。红树林的损失一直在放缓,如果未来的损失率继续降低,那么全球排放量可能会减少一半以上。值得注意的是,全球排放热点的位置与用来计算森林砍伐率的每个数据集一致,或者与关于碳储存和排放的替代假设一致。我们的研究结果表明,需要采取政策行动的地区是那些需要解决由于红树林损失而产生的排放问题的地区,以及那些可以通过管理来防止排放的驱动因素。