Climate-driven shifts in continental net primary production implicated as a driver of a recent abrupt increase in the land carbon sink
Climate-driven shifts in continental net primary production implicated as a driver of a recent abrupt increase in the land carbon sink
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DOI：
10.5194/bg-13-1597-2016
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发表时间：
2016-01-01
期刊：
影响因子：
4.9
通讯作者：
Sarmiento, Jorge L.
中科院分区：
文献类型：
--
作者：
Buermann, Wolfgang;Beaulieu, Claudie;Sarmiento, Jorge L.
世界上的海洋和陆地生态系统充当了人为二氧化碳的汇，在过去的半个世纪里，它们的总汇强度随着二氧化碳排放量的增加而稳步增长。然而，最近对全球碳收支的分析发现，20世纪80年代末土地汇突然大幅增加(类似于1PGC yr(-1))并持续增加，其来源尚不清楚。如果没有陆地汇的这种显著变化，自20世纪80年代末以来大气二氧化碳浓度的增加将类似于比观测到的高出30%(或类似于比当前水平高出12ppm)。在将原因归因于土地下沉变化方面，全球数据分析有限，因为不同的地区可能对不同的驱动因素做出反应。在这里，我们通过使用受观测约束的陆地生物圈模型来解决这一挑战，以确定是否有独立的证据表明陆地下沉突然加强。我们发现，净初级生产力在20世纪80年代末显著增加(超过异养呼吸)，这与推断的全球土地汇增加是一致的，这种转变是由大范围气候异常造成的。我们确定了两个对植物生长的气候限制已经缓解的关键地区：欧亚大陆北部经历了变暖，北非降水增加。大陆气候的这些变化是否有关联尚不确定，但北大西洋气候的变化是重要的。我们的发现表明，更好地了解北大西洋的气候变异性，对于更可信地预测气候变化下的陆地下沉可能是至关重要的。
The world's ocean and land ecosystems act as sinks for anthropogenic CO2, and over the last half century their combined sink strength grew steadily with increasing CO2 emissions. Recent analyses of the global carbon budget, however, have uncovered an abrupt, substantial (similar to 1 PgC yr(-1)) and sustained increase in the land sink in the late 1980s whose origin remains unclear. In the absence of this prominent shift in the land sink, increases in atmospheric CO2 concentrations since the late 1980s would have been similar to 30% larger than observed (or similar to 12 ppm above current levels). Global data analyses are limited in regards to attributing causes to changes in the land sink because different regions are likely responding to different drivers. Here, we address this challenge by using terrestrial biosphere models constrained by observations to determine if there is independent evidence for the abrupt strengthening of the land sink. We find that net primary production significantly increased in the late 1980s (more so than heterotrophic respiration), consistent with the inferred increase in the global land sink, and that large-scale climate anomalies are responsible for this shift. We identify two key regions in which climatic constraints on plant growth have eased: northern Eurasia experienced warming, and northern Africa received increased precipitation. Whether these changes in continental climates are connected is uncertain, but North Atlantic climate variability is important. Our findings suggest that improved understanding of climate variability in the North Atlantic may be essential for more credible projections of the land sink under climate change.