Climate change is warming the ocean and impacting lower trophic level (LTL) organisms. Marine ecosystem models can provide estimates of how these changes will propagate to larger animals and impact societal services such as fisheries, but at present these estimates vary widely. A better understanding of what drives this inter-model variation will improve our ability to project fisheries and other ecosystem services into the future, while also helping to identify uncertainties in process understanding. Here, we explore the mechanisms that underlie the diversity of responses to changes in temperature and LTLs in eight global marine ecosystem models from the Fisheries and Marine Ecosystem Model Intercomparison Project (FishMIP). Temperature and LTL impacts on total consumer biomass and ecosystem structure (defined as the relative change of small and large organism biomass) were isolated using a comparative experimental protocol. Total model biomass varied between −35% to +3% in response to warming, and -17% to +15% in response to LTL changes. There was little consensus about the spatial redistribution of biomass or changes in the balance between small and large organisms (ecosystem structure) in response to warming, an LTL impacts on total consumer biomass varied depending on the choice of LTL forcing terms. Overall, climate change impacts on consumer biomass and ecosystem structure are well approximated by the sum of temperature and LTL impacts, indicating an absence of nonlinear interaction between the models’ drivers. Our results highlight a lack of theoretical clarity about how to represent fundamental ecological mechanisms, most importantly how temperature impacts scale from individual to ecosystem level, and the need to better understand the two-way coupling between LTL organisms and consumers. We finish by identifying future research needs to strengthen global marine ecosystem modelling and improve projections of climate change impacts.

气候变化正在使海洋变暖并影响低营养级 (LTL) 生物。海洋生态系统模型可以估计这些变化将如何传播到更大的动物并影响渔业等社会服务，但目前这些估计差异很大。更好地了解驱动这种模型间变化的原因将提高我们将渔业和其他生态系统服务预测到未来的能力，同时也有助于识别过程理解中的不确定性。在这里，我们探索了渔业和海洋生态系统模型比对项目 (FishMIP) 中八个全球海洋生态系统模型中温度和 LTL 变化响应多样性的机制。温度和 LTL 对总消费者生物量和生态系统结构（定义为小型和大型生物体生物量的相对变化）的影响使用比较实验方案进行了分离。总模型生物量在-35% 到 +3% 之间变化，以响应变暖，-17% 到 +15% 响应 LTL 变化。关于生物量的空间重新分布或小型和大型生物（生态系统结构）之间的平衡变化以响应变暖几乎没有共识，LTL 对总消费者生物量的影响取决于 LTL 强迫术语的选择。总体而言，气候变化对消费者生物量和生态系统结构的影响可以通过温度和 LTL 影响的总和很好地近似，表明模型驱动因素之间不存在非线性相互作用。我们的结果强调了关于如何表示基本生态机制的理论缺乏清晰度，最重要的是温度如何影响从个体到生态系统水平的规模，以及需要更好地理解 LTL 生物和消费者之间的双向耦合。最后，我们确定了未来的研究需求，以加强全球海洋生态系统建模并改进对气候变化影响的预测。