Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada;
Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
Proc Natl Acad Sci U S A. 2019 Jun 25;116(26):12907-12912. doi: 10.1073/pnas.1900194116. Epub 2019 Jun 11.
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 °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.
虽然气候变化的物理维度现在通常通过多模型比较来评估，但对全球海洋生态系统的预计影响通常依赖于具有特定假设的个别模型。为了解决这些单一模型的局限性，我们提出了六个全球海洋生态系统模型在两种地球系统模型和四种排放情景下的标准化集合预测，包括有和没有捕捞的情景。我们得出了海洋食物网中整个生物量的趋势和相关不确定性。在没有捕捞的情况下，到 2100 年，低排放情景下全球动物生物量平均减少 5%（±4% SD），高排放情景下减少 17%（±11% SD），每升温 1°C 平均减少 5%。预计生物量下降的主要原因是温度升高和初级生产力下降，在较高的营养级中更为明显，这一过程称为营养级放大。捕捞并没有显著改变气候变化的影响。一些地区的变化显著，高纬度地区的生物量增加，中低纬度地区的生物量减少，模型在变化方向上达成了很好的一致，但变化幅度有所不同。海洋生态系统和地球系统模型的变化导致的不确定性相似。与经验数据相比，集合预测表现良好，强调了多模型推断在预测未来结果方面的优势。我们的研究结果表明，全球海洋动物生物量随着气候变化而持续下降，而且这些影响在较高的营养级中更为明显。模型开发的下一步包括捕捞的动态情景、人类累积影响以及管理措施对未来海洋生物量趋势的影响。
