Sudden emergence of a shallow aragonite saturation horizon in the Southern Ocean
Sudden emergence of a shallow aragonite saturation horizon in the Southern Ocean
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DOI：
10.1038/s41558-019-0418-8
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发表时间：
2019-03
影响因子：
30.7
通讯作者：
Gabriela Negrete-García;N. Lovenduski;C. Hauri;K. Krumhardt;S. Lauvset
中科院分区：
文献类型：
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作者：
Gabriela Negrete-García;N. Lovenduski;C. Hauri;K. Krumhardt;S. Lauvset
模型预测，按照目前的二氧化碳排放速度，到本世纪末，南大洋表面文石的含量将达到不饱和。这将对生物地球化学和海洋生态系统造成广泛的影响，特别是文石生物的健康，如翼足目动物，它们可以主宰极地地表水群落。在这里，我们使用水文和海洋碳化学观测来量化今天南大洋文石饱和层的深度，并使用共同体地球系统模型(CESM)的大量模拟来跟踪其演变。从现在到本世纪末，在南大洋的许多地点出现了一个新的浅层文石饱和层。虽然所有的集合成员都捕捉到了出现，但内部气候变化可能会影响出现的年份；因此，它的检测可能被过去的集合平均分析所忽视。新层位的出现是由人为CO2在南大洋温跃层中缓慢积累所推动的，那里的碳酸盐离子浓度表现出局部最小值，并接近饱和。在稳定排放的情况下，新的地平线也很明显，表明适合文石生物栖息地的数量不可避免地突然减少。
Models project that with current CO2emission rates, the Southern Ocean surface will be undersaturated with respect to aragonite by the end of this century, , –. This will result in widespread impacts on biogeochemistry and ocean ecosystems, –, particularly the health of aragonitic organisms, such as pteropods, which can dominate polar surface water communities. Here, we quantify the depth of the present-day Southern Ocean aragonite saturation horizon using hydrographic and ocean carbon chemistry observations, and use a large ensemble of simulations from the Community Earth System Model (CESM),to track its evolution. A new, shallow aragonite saturation horizon emerges in many Southern Ocean locations between now and the end of the century. While all ensemble members capture the emergence, internal climate variability may affect the year of emergence; thus, its detection may have been overlooked by ensemble average analysis in the past. The emergence of the new horizon is driven by the slow accumulation of anthropogenic CO2in the Southern Ocean thermocline, where the carbonate ion concentration exhibits a local minimum and approaches undersaturation. The new horizon is also apparent under an emission-stabilizing scenario indicating an inevitable, sudden decrease in the volume of suitable habitat for aragonitic organisms.