Methane Emissions in a Chemistry-Climate Model: Feedbacks and Climate Response.
Methane Emissions in a Chemistry-Climate Model: Feedbacks and Climate Response.
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DOI：
10.1029/2019ms002019
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发表时间：
2020-10
影响因子：
6.8
通讯作者：
Pyle JA
中科院分区：
文献类型：
--
作者：
Heimann I;Griffiths PT;Warwick NJ;Abraham NL;Archibald AT;Pyle JA
了解甲烷的过去、现在和未来的演变仍然是一个巨大的挑战。在这里，我们使用了一系列模型，从简单的箱模型到化学气候模型（CCM），UM‐UKCA，来评估当代和未来可能的大气甲烷负担。我们评估了两个排放数据集，2000年部署在UM‐UKCA对关键观测的限制。我们探讨了模型边界条件对甲烷处理的影响，并表明，根据其他因素，如CO排放量，可以获得满意的协议与任何一个CH 4排放数据集，突出强调明确选择模型排放量的困难，在耦合化学模型与强反馈。CH 4-CO-OH系统中的反馈及其不确定性在预测可能的未来中起着关键作用。在未来，温室气体强迫的大幅增加，对流层温度驱动的增加，水蒸气的增加，以及[OH]的增加。在甲烷排放量没有变化的情况下，这导致甲烷与2000年相比显著减少。然而，增加RCP8.5情景中甲烷排放量的预计增加会导致甲烷丰度大幅增加。这会通过CO和NOx排放量的变化进行修改。显然，未来的甲烷水平是不确定的，主要取决于气候变化以及甲烷和臭氧前体的未来排放途径。我们强调，需要进一步的工作来了解耦合CH 4-CO-OH系统，以便更好地了解未来的甲烷演化。我们在一个采用基于通量的甲烷排放处理的模型中研究了当前和未来气候中的甲烷我们使用0-D箱模型和3-D化学气候模型研究了CH 4-CO-OH系统中反馈的来源和重要性我们研究了未来气候中的甲烷水平以及气候和排放变化所扮演的角色
Understanding the past, present, and future evolution of methane remains a grand challenge. Here we have used a hierarchy of models, ranging from simple box models to a chemistry‐climate model (CCM), UM‐UKCA, to assess the contemporary and possible future atmospheric methane burden. We assess two emission data sets for the year 2000 deployed in UM‐UKCA against key observational constraints. We explore the impact of the treatment of model boundary conditions for methane and show that, depending on other factors, such as CO emissions, satisfactory agreement may be obtained with either of the CH4 emission data sets, highlighting the difficulty in unambiguous choice of model emissions in a coupled chemistry model with strong feedbacks. The feedbacks in the CH4‐CO‐OH system, and their uncertainties, play a critical role in the projection of possible futures. In a future driven by large increases in greenhouse gas forcing, increases in tropospheric temperature drive, an increase in water vapor, and, hence, [OH]. In the absence of methane emission changes this leads to a significant decrease in methane compared to the year 2000. However, adding a projected increase in methane emissions from the RCP8.5 scenario leads to a large increase in methane abundance. This is modified by changes to CO and NOx emissions. Clearly, future levels of methane are uncertain and depend critically on climate change and on the future emission pathways of methane and ozone precursors. We highlight that further work is needed to understand the coupled CH4‐CO‐OH system in order to understand better future methane evolution. We study methane in present and future climate in a model employing flux‐based treatment of methane emissions We examine the source and importance of feedbacks in the CH4‐CO‐OH system using a 0‐D box model and a 3‐D chemistry‐climate model We examine methane levels in future climate and the role played by climate and emissions changes