Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change
Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change
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DOI：
10.1073/pnas.1900194116
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发表时间：
2019-06-25
影响因子：
11.1
通讯作者：
Worm, Boris
中科院分区：
文献类型：
--
作者：
Lotze, Heike K.;Tittensor, Derek P.;Worm, Boris
虽然现在通常通过多模型间比较来评估气候变化的物理层面，但对全球海洋生态系统的预测影响一般依赖于具有一套具体假设的个别模型。为了解决这些单一模型的局限性，我们提出了来自六个全球海洋生态系统模型的标准化总体预测，其中包括两个地球系统模型和四个有无捕鱼的排放情景。我们得出了整个海洋食物网的平均生物量趋势和相关的不确定性。在没有捕捞的情况下，到2100年，全球平均动物生物量在低排放下下降了5%(+/-4%SD)，在高排放下下降了17%(+/-11%SD)，平均每升温1摄氏度就下降5%。预计生物量下降主要是由气温上升和初级生产量减少推动的，在营养水平较高的情况下，这一过程更为明显，这一过程被称为营养放大。渔业并没有在很大程度上改变气候变化的影响。相当大的区域差异表现为高纬度生物量显著增加，中低纬度生物量减少，变化方向模型吻合较好，但变化幅度不同。海洋生态系统和地球系统模型的变化造成的不确定性是相似的。与经验数据相比，总体预测表现良好，强调了多模型推理对预测未来结果的好处。我们的结果表明，全球海洋动物生物量随着气候变化而持续下降，并且这些影响在营养水平较高时被放大。模型开发的下一步包括捕捞的动态情景、累积的人类影响以及管理措施对未来海洋生物量趋势的影响。
While the physical dimensions of climate change are now routinely assessed through multimodel intercomparisons, projected impacts on the global ocean ecosystem generally rely on individual models with a specific set of assumptions. To address these single-model limitations, we present standardized ensemble projections from six global marine ecosystem models forced with two Earth system models and four emission scenarios with and without fishing. We derive average biomass trends and associated uncertainties across the marine food web. Without fishing, mean global animal biomass decreased by 5% (+/- 4% SD) under low emissions and 17% (+/- 11% SD) under high emissions by 2100, with an average 5% decline for every 1 degrees C of warming. Projected biomass declines were primarily driven by increasing temperature and decreasing primary production, and were more pronounced at higher trophic levels, a process known as trophic amplification. Fishing did not substantially alter the effects of climate change. Considerable regional variation featured strong biomass increases at high latitudes and decreases at middle to low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to variations in marine ecosystem and Earth system models were similar. Ensemble projections performed well compared with empirical data, emphasizing the benefits of multimodel inference to project future outcomes. Our results indicate that global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels. Next steps for model development include dynamic scenarios of fishing, cumulative human impacts, and the effects of management measures on future ocean biomass trends.