Impact of accelerated future global mean sea level rise on hypoxia in the Baltic Sea
Impact of accelerated future global mean sea level rise on hypoxia in the Baltic Sea
复制标题
未来全球平均海平面加速上升对波罗的海缺氧的影响
DOI：
10.1007/s00382-016-3333-y
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发表时间：
2017
期刊：
影响因子：
4.6
通讯作者：
E. Almroth‐Rosell
中科院分区：
文献类型：
--
作者：
H. Meier;A. Höglund;K. Eilola;E. Almroth‐Rosell
摘要 日益严重的缺氧问题是当今世界许多沿海海域的主要威胁，而弄清楚其驱动因素是跨学科研究的一大挑战。使用物理-生物地球化学耦合模型，我们估计了过去和未来加速的全球平均海平面上升（GSLR）对半封闭浅海的水交换和氧气条件的影响。选择波罗的海作为研究地点，该海目前正遭受富营养化和死底区的影响，原因是（1）来自陆地的养分负荷过多，（2）与世界海洋的水交换有限，以及（3）可能是全球变暖等其他驱动因素。我们通过 1850-2008 年期间的模型模拟表明，过去的 GSLR 对海洋生态系统的影响相对较小。如果我们假设 21 世纪末的 GSLR 相对于今天的平均海平面为 +0.5 m，那么对海洋生态系统的影响可能仍然很小。这样的 GSLR 大约对应于政府间气候变化专门委员会第五次评估报告报告的预计集合平均值。然而，我们的结论是，在波罗的海和与波罗的海水文条件相似的其他沿海海域的未来高端预测（>+1 m）中应考虑 GSLR，因为 GSLR 可能会导致海水流入加强，导致与目前的情况相比盐度更高并增加垂直分层。与直觉相反，加强深水通风并不会导致氧气条件总体改善，反而会导致死底区域扩大，同时沉积物内部磷负荷增加，并增加蓝藻水华的风险。
Abstract Expanding hypoxia is today a major threat for many coastal seas around the world and disentangling its drivers is a large challenge for interdisciplinary research. Using a coupled physical-biogeochemical model we estimate the impact of past and accelerated future global mean sea level rise (GSLR) upon water exchange and oxygen conditions in a semi-enclosed, shallow sea. As a study site, the Baltic Sea was chosen that suffers today from eutrophication and from dead bottom zones due to (1) excessive nutrient loads from land, (2) limited water exchange with the world ocean and (3) perhaps other drivers like global warming. We show from model simulations for the period 1850–2008 that the impacts of past GSLR on the marine ecosystem were relatively small. If we assume for the end of the twenty-first century a GSLR of +0.5 m relative to today’s mean sea level, the impact on the marine ecosystem may still be small. Such a GSLR corresponds approximately to the projected ensemble-mean value reported by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. However, we conclude that GSLR should be considered in future high-end projections (>+1 m) for the Baltic Sea and other coastal seas with similar hydrographical conditions as in the Baltic because GSLR may lead to reinforced saltwater inflows causing higher salinity and increased vertical stratification compared to present-day conditions. Contrary to intuition, reinforced ventilation of the deep water does not lead to overall improved oxygen conditions but causes instead expanded dead bottom areas accompanied with increased internal phosphorus loads from the sediments and increased risk for cyanobacteria blooms.