Five decades of northern land carbon uptake revealed by the interhemispheric CO2 gradient
Five decades of northern land carbon uptake revealed by the interhemispheric CO2 gradient
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DOI：
10.1038/s41586-019-1078-6
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发表时间：
2019-04-11
期刊：
影响因子：
64.8
通讯作者：
Tans, P.
中科院分区：
文献类型：
--
作者：
Ciais, P.;Tan, J.;Tans, P.
在过去的几十年里，全球陆地和海洋碳汇随着二氧化碳排放量的增加而成比例增加（1）。人们认为，北方陆地对全球陆地碳汇的贡献占主导地位（2-7）;然而，北方陆地碳汇的长期趋势仍不确定。在这里，使用1958年至2016年大气二氧化碳的半球间梯度测量，我们表明北方陆地汇在20世纪60年代至80年代末保持稳定，然后在20世纪90年代每年增加0.5 +/- 0.4 petagram碳，在21世纪初每年增加0.6 +/- 0.5 petagram碳。20世纪90年代北方陆地碳汇的增加占同期全球陆地碳通量增加的65%。随后在2000年代的增加大于全球陆地碳通量的增加，这表明南半球的碳吸收量同时减少。将我们的研究结果与同期陆地碳模式集合的模拟结果（5，8）进行比较表明，北方陆地汇在20世纪60年代和90年代之间的年代际变化可以用大气二氧化碳浓度增加、气候变率和土地覆盖变化的组合来解释。然而，所有模型都低估了2000年代的增长，这表明需要更好地考虑氮沉降、漫射光和土地使用变化等驱动因素的变化。总的来说，我们的研究结果强调了北方半球土地作为碳汇的重要性。
The global land and ocean carbon sinks have increased proportionally with increasing carbon dioxide emissions during the past decades(1). It is thought that Northern Hemisphere lands make a dominant contribution to the global land carbon sink(2-7); however, the long-term trend of the northern land sink remains uncertain. Here, using measurements of the interhemispheric gradient of atmospheric carbon dioxide from 1958 to 2016, we show that the northern land sink remained stable between the 1960s and the late 1980s, then increased by 0.5 +/- 0.4 petagrams of carbon per year during the 1990s and by 0.6 +/- 0.5 petagrams of carbon per year during the 2000s. The increase of the northern land sink in the 1990s accounts for 65% of the increase in the global land carbon flux during that period. The subsequent increase in the 2000s is larger than the increase in the global land carbon flux, suggesting a coincident decrease of carbon uptake in the Southern Hemisphere. Comparison of our findings with the simulations of an ensemble of terrestrial carbon models(5,8) over the same period suggests that the decadal change in the northern land sink between the 1960s and the 1990s can be explained by a combination of increasing concentrations of atmospheric carbon dioxide, climate variability and changes in land cover. However, the increase during the 2000s is underestimated by all models, which suggests the need for improved consideration of changes in drivers such as nitrogen deposition, diffuse light and land-use change. Overall, our findings underscore the importance of Northern Hemispheric land as a carbon sink.