海洋是一大碳汇，吸收约三分之一由人类活动造成的CO2排放，但CO2捕获的分布和速度存在相当大的不确定性。Khatiwala等人介绍了对在工业时代海洋中所吸收的由人类活动排放的碳所做的一个基于观测的重建工作。他们绘制了碳浓度最大的地区的分布图，并跟踪了碳随时间的积累。他们的发现表明，海洋对由人类活动排放的碳的吸收自上个世纪50年代以来急剧增长，在最近几十年增长速度有小幅下降。南大洋是最大的碳汇，占吸收总量的40%以上。这些结果还表明，陆地生物圈在上个世纪40年代以前一直是CO2的一个源，但随后变成了一个汇。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 462, 346-349 (19 November 2009) | doi:10.1038/nature08526
Reconstruction of the history of anthropogenic CO2 concentrations in the ocean
S. Khatiwala1, F. Primeau2 & T. Hall3
1 Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA
2 Department of Earth System Science, University of California, Irvine, California 92697, USA
3 NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York 10025, USA
4 Correspondence to: S. Khatiwala1 Correspondence and requests for materials should be addressed to S.K.
The release of fossil fuel CO2 to the atmosphere by human activity has been implicated as the predominant cause of recent global climate change1. The ocean plays a crucial role in mitigating the effects of this perturbation to the climate system, sequestering 20 to 35 per cent of anthropogenic CO2 emissions2, 3, 4. Although much progress has been made in recent years in understanding and quantifying this sink, considerable uncertainties remain as to the distribution of anthropogenic CO2 in the ocean, its rate of uptake over the industrial era, and the relative roles of the ocean and terrestrial biosphere in anthropogenic CO2 sequestration. Here we address these questions by presenting an observationally based reconstruction of the spatially resolved, time-dependent history of anthropogenic carbon in the ocean over the industrial era. Our approach is based on the recognition that the transport of tracers in the ocean can be described by a Green's function, which we estimate from tracer data using a maximum entropy deconvolution technique. Our results indicate that ocean uptake of anthropogenic CO2 has increased sharply since the 1950s, with a small decline in the rate of increase in the last few decades. We estimate the inventory and uptake rate of anthropogenic CO2 in 2008 at 140 25 Pg C and 2.3 0.6 Pg C yr-1, respectively. We find that the Southern Ocean is the primary conduit by which this CO2 enters the ocean (contributing over 40 per cent of the anthropogenic CO2 inventory in the ocean in 2008). Our results also suggest that the terrestrial biosphere was a source of CO2 until the 1940s, subsequently turning into a sink. Taken over the entire industrial period, and accounting for uncertainties, we estimate that the terrestrial biosphere has been anywhere from neutral to a net source of CO2, contributing up to half as much CO2 as has been taken up by the ocean over the same period.
