Can we trust empirical marine DMS parameterisations within projections of future climate?
Can we trust empirical marine DMS parameterisations within projections of future climate?
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DOI：
10.5194/bg-7-1645-2010
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发表时间：
2010-01-01
期刊：
影响因子：
4.9
通讯作者：
Totterdell, I. J.
中科院分区：
文献类型：
--
作者：
Halloran, P. R.;Bell, T. G.;Totterdell, I. J.
二甲基硫（DMS）是一种全球性的重要气溶胶污染物。1987年，Charlson和其他人提出，某些浮游植物因气候变暖而产生的二甲硫醚产量增加，可能会刺激气溶胶的形成，增加低层大气的蒸发量，并促进冷却。尽管经过二十年的研究，这种负面气候反馈的全球意义仍然存在争议。因此，必须制定和测试计划，以便将浮游植物二甲基硫醚的生产实际纳入地球系统模型。使用这些模型，我们可以调查DMS气候反馈，减少未来气候预测的不确定性。在这里，我们研究了两个经验DMS参数化的背景下，地球系统模型，并发现他们执行略优于标准DMS气候学预测观测从一个独立的全球数据集。然后，我们质疑是否参数化的基础上，我们目前的理解二甲基硫生产的浮游植物，并简单到足以纳入全球气候模型，可以证明，以提高未来的预测能力，这些模型。这是一个现在要问的重要问题，因为越来越复杂的地球系统模型的结果将我们带入政府间气候变化专门委员会对气候科学的第五次评估。比较观测和预测的年际变化，我们认为，未来的气候预测可能会低估了海洋表层DMS变化的幅度。不幸的是，这一结论依赖于一个相对较小的数据集，其中观察到的年际变化可能会被夸大的样本收集的偏见。因此，我们鼓励观测界将重复测量海面二甲硫醚浓度作为一个重要的重点，并强调可能进行采样的年际变化明显较大的地区。最后，我们评估未来的预测，从两个同样有效的经验DMS计划，并展示对比结果。因此，我们的结论是，在模拟未来气候的经验DMS参数化的使用，应进行只有与讨论的警告仔细欣赏。
Dimethylsulphide (DMS) is a globally important aerosol precurser. In 1987 Charlson and others proposed that an increase in DMS production by certain phytoplankton species in response to a warming climate could stimulate increased aerosol formation, increasing the lower-atmosphere's albedo, and promoting cooling. Despite two decades of research, the global significance of this negative climate feedback remains contentious. It is therefore imperative that schemes are developed and tested, which allow for the realistic incorporation of phytoplankton DMS production into Earth System models. Using these models we can investigate the DMS-climate feedback and reduce uncertainty surrounding projections of future climate. Here we examine two empirical DMS parameterisations within the context of an Earth System model and find them to perform marginally better than the standard DMS climatology at predicting observations from an independent global dataset. We then question whether parameterisations based on our present understanding of DMS production by phytoplankton, and simple enough to incorporate into global climate models, can be shown to enhance the future predictive capacity of those models. This is an important question to ask now, as results from increasingly complex Earth System models lead us into the 5th assessment of climate science by the Intergovernmental Panel on Climate Change. Comparing observed and predicted inter-annual variability, we suggest that future climate projections may underestimate the magnitude of surface ocean DMS change. Unfortunately this conclusion relies on a relatively small dataset, in which observed inter-annual variability may be exaggerated by biases in sample collection. We therefore encourage the observational community to make repeat measurements of sea-surface DMS concentrations an important focus, and highlight areas of apparent high inter-annual variability where sampling might be carried out. Finally, we assess future projections from two similarly valid empirical DMS schemes, and demonstrate contrasting results. We therefore conclude that the use of empirical DMS parameterisations within simulations of future climate should be undertaken only with careful appreciation of the caveats discussed.