We investigate the relative importance of ecosystem complexity and phytoplankton light absorption for climate studies. While the complexity of Earth System models (ESMs) with respect to marine biota has increased over the past years, the relative importance of biological processes in driving climate‐relevant mechanisms such as the biological carbon pump and phytoplankton light absorption is still unknown. The climate effects of these mechanisms have been studied separately, but not together. To shed light on the role of biologically mediated feedbacks, we performed different model experiments with the EcoGENIE ESM. The model experiments have been conducted with and without phytoplankton light absorption and with two or 12 plankton functional types. For a robust comparison, all simulations are tuned to have the same primary production. Our model experiments show that phytoplankton light absorption changes ocean physics and biogeochemistry. Higher sea surface temperature decreases the solubility of CO₂ which in turn increases the atmospheric CO₂ concentration, and finally the atmospheric temperature rises by 0.45°C. An increase in ecosystem complexity increases the export production of particulate organic carbon but decreases the amount of dissolved organic matter. These changes in the marine carbon cycling, however, hardly reduces the atmospheric CO₂ concentrations and slightly decreases the atmospheric temperature by 0.034°C. Overall we show that phytoplankton light absorption has a higher impact on the carbon cycle and on the climate system than a more detailed representation of the marine biota.

中文翻译：

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地球系统模型中浮游植物光吸收和生态系统复杂性的相对重要性

我们调查了生态系统复杂性和浮游植物光吸收在气候研究中的相对重要性。尽管在过去几年中，地球系统模型（ESM）在海洋生物群方面的复杂性有所增加，但生物过程在驱动与气候相关的机制（例如生物碳泵和浮游植物光吸收）中的相对重要性仍然未知。这些机制对气候的影响已经分别研究，但没有一起研究。为了阐明生物媒介反馈的作用，我们使用EcoGENIE ESM进行了不同的模型实验。在有或没有浮游植物光吸收以及具有两种或12种浮游生物功能类型的情况下进行了模型实验。为了进行可靠的比较，所有模拟都调整为具有相同的主要产量。我们的模型实验表明，浮游植物的光吸收改变了海洋物理和生物地球化学。较高的海面温度降低了一氧化碳的溶解度_{如图2所示}，这又增加了大气中CO _2的浓度，最终大气温度升高了0.45℃。生态系统复杂性的增加增加了颗粒状有机碳的出口产量，但减少了溶解有机物的量。但是，海洋碳循环中的这些变化几乎不会降低大气中的CO ₂浓度，而会使大气温度略微降低0.034°C。总体而言，我们显示出浮游植物的光吸收比海洋生物群的更详细表示对碳循环和气候系统的影响更大。