Schimel D S, House J I, Hibbard K A, Bousquet P, Ciais P, Peylin P, Braswell B H, Apps M J, Baker D, Bondeau A, Canadell J, Churkina G, Cramer W, Denning A S, Field C B, Friedlingstein P, Goodale C, Heimann M, Houghton R A, Melillo J M, Moore B, Murdiyarso D, Noble I, Pacala S W, Prentice I C, Raupach M R, Rayner P J, Scholes R J, Steffen W L, Wirth C
Max Planck Institute für Biogeochemie, Jena, Germany.
Nature. 2001 Nov 8;414(6860):169-72. doi: 10.1038/35102500.
Knowledge of carbon exchange between the atmosphere, land and the oceans is important, given that the terrestrial and marine environments are currently absorbing about half of the carbon dioxide that is emitted by fossil-fuel combustion. This carbon uptake is therefore limiting the extent of atmospheric and climatic change, but its long-term nature remains uncertain. Here we provide an overview of the current state of knowledge of global and regional patterns of carbon exchange by terrestrial ecosystems. Atmospheric carbon dioxide and oxygen data confirm that the terrestrial biosphere was largely neutral with respect to net carbon exchange during the 1980s, but became a net carbon sink in the 1990s. This recent sink can be largely attributed to northern extratropical areas, and is roughly split between North America and Eurasia. Tropical land areas, however, were approximately in balance with respect to carbon exchange, implying a carbon sink that offset emissions due to tropical deforestation. The evolution of the terrestrial carbon sink is largely the result of changes in land use over time, such as regrowth on abandoned agricultural land and fire prevention, in addition to responses to environmental changes, such as longer growing seasons, and fertilization by carbon dioxide and nitrogen. Nevertheless, there remain considerable uncertainties as to the magnitude of the sink in different regions and the contribution of different processes.
鉴于陆地和海洋环境目前吸收了化石燃料燃烧排放的约一半二氧化碳，了解大气、陆地和海洋之间的碳交换至关重要。因此，这种碳吸收限制了大气和气候变化的程度，但其长期性质仍不确定。在此，我们概述陆地生态系统碳交换全球和区域模式的当前知识状况。大气二氧化碳和氧气数据证实，陆地生物圈在20世纪80年代的净碳交换方面基本呈中性，但在20世纪90年代成为净碳汇。近期的这个碳汇很大程度上可归因于北温带地区，且大致在北美和欧亚大陆之间平分。然而，热带陆地地区在碳交换方面大致处于平衡状态，这意味着存在一个抵消热带森林砍伐所致排放的碳汇。陆地碳汇的演变在很大程度上是土地利用随时间变化的结果，比如废弃农田的重新生长和防火措施，此外还有对环境变化的响应，比如生长季节延长以及二氧化碳和氮的施肥作用。尽管如此，不同区域碳汇的规模以及不同过程的贡献仍存在相当大的不确定性。
