Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models
Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models
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DOI：
10.5194/bg-13-5151-2016
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发表时间：
2016-09-16
期刊：
影响因子：
4.9
通讯作者：
Moore, J. Keith
中科院分区：
文献类型：
--
作者：
Fu, Weiwei;Randerson, James T.;Moore, J. Keith
我们研究了气候变化对净初级生产力（NPP）和出口生产（沉降颗粒通量; EP）的影响，并在耦合模型相互比较项目（CMIP 5）的第五阶段框架内进行了9个地球系统模型（ESM）的模拟。在代表性浓度路径（RCP）8.5的强变暖情景下，全球NPP和EP在世纪末减少。与1990年代相比，2090年代的NPP减少2-16%，EP减少7- 18%。分层增加幅度最大（NPP和EP相对下降幅度最大）的模型也显示出当代分层的最大正偏差，表明高估了气候变化对NPP和EP的影响。所有的CMIP 5模型显示，响应于表面海洋变暖和淡化，这是伴随着减少表面营养物质，NPP和EP分层的增加。有相当大的变化，在NPP，EP，表面营养浓度和它们的扰动气候变化的幅度跨模型。NPP和EP的负响应，增加分层主要反映了自下而上的控制，向上的营养通量下降，在全球范围内。具有动态浮游植物群落结构的模型显示，EP的下降幅度大于NPP。这种模式是由浮游植物群落组成变化驱动的，大型浮游植物的生产力下降，因为较小的浮游植物（输出效率较低）在不断增加的营养压力下受到青睐。因此，NPP对气候变化响应的预测主要取决于模拟的浮游植物群落结构、生物泵的效率以及由此产生的再生生产水平，这些在模型中差异很大。社区结构在CMIP 5模型中仅得到简单的表示，应加以扩展，以更好地捕捉出口效率的空间格局和气候驱动的变化。
We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth system models (ESMs) performed in the framework of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Global NPP and EP are reduced by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, NPP in the 2090s is reduced by 2-16% and EP by 7-18 %. The models with the largest increases in stratification (and largest relative declines in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting overestimation of climate change impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface-ocean warming and freshening, which is accompanied by decreases in surface nutrients, NPP and EP.There is considerable variability across the models in the magnitudes of NPP, EP, surface nutrient concentrations and their perturbations by climate change. The negative response of NPP and EP to increasing stratification reflects primarily a bottom-up control, as upward nutrient flux declines at the global scale. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This pattern is driven by phytoplankton community composition shifts, with reductions in productivity by large phytoplankton as smaller phytoplankton (which export less efficiently) are favored under the increasing nutrient stress. Thus, the projections of the NPP response to climate change are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump and the resulting levels of regenerated production, which vary widely across the models. Community structure is represented simply in the CMIP5 models, and should be expanded to better capture the spatial patterns and climate-driven changes in export efficiency.