Changing concentration, lifetime and climate forcing of atmospheric methane
Changing concentration, lifetime and climate forcing of atmospheric methane
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DOI：
10.1034/j.1600-0889.1998.t01-1-00002.x
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发表时间：
1998-04-01
影响因子：
2.3
通讯作者：
Dentener, FJ
中科院分区：
文献类型：
--
作者：
Lelieveld, J;Crutzen, PJ;Dentener, FJ
以前对冰芯分析的研究和最近的现场测量表明，在过去的150年里，甲烷的含量从大约0.75增加到1.73mU/mol。在这里，我们回顾了来源和汇估计，我们提供了全球3D模型计算，表明全球CH4分布的主要特征得到了很好的代表。利用该模型推导出甲烷排放总量约为600TgYr(-1)。根据已公布的同位素测量结果，与化石燃料相关的CHI排放的总贡献率已估计为约110Tg/年。然而，与煤、天然气和石油相关的单个CH4排放量无法准确量化。特别是，与天然气和石油相关的排放量仍然是投机性的。由于总的人为CH4源约为410tgyr(-1)(相当于总源量的70%)，而近期大气CH4的平均增加类似于20tgyr(-1)，人为源减少5%可以稳定大气中的CH4水平。我们在全球三维化学输送和辐射输送计算的基础上，计算了甲烷增加对气候强迫的间接化学效应。这表明直接辐射效应增强了约30%，与前人的工作一致，过去150年来CH4(直接和间接影响)对气候强迫的贡献为0.57Wm(-2)(直接0.44Wm(-2)，间接0.13Wm(-2))。这大约是二氧化碳(1.6Wm(-2))造成的气候强迫的35%，是所有长期温室气体(2.6Wm(-2))强迫的22%左右。情景计算(IPCC-IS92a)表明，在过去150年中，大气中甲烷的寿命增加了约25%-30%，目前为7.9年。未来的寿命变化预计要小得多，约为6%，主要是由于热带地区对流层O-3(->；OH)的预期增加。到2050年，全球甲烷的平均浓度可能增加到2.55mU/m o l左右，其寿命有望增加到8.4年。此外，与IPCC(1996)一致，我们计算了100年时间范围内CH4全球变暖潜势(GWP)为21(kgCH(4)/kgCO(2))。情景计算表明，未来CH4的气候强迫(包括间接影响)相对于CO2的重要性将降低；目前这一重要性约为35%，预计到2050年将降至约15%。
Previous studies on ice core analyses and recent in situ measurements have shown that CH4 has increased from about 0.75 to 1.73 mu mol/mol during the past 150 years. Here, we review sources and sink estimates and we present global 3D model calculations, showing that the main features of the global CH4 distribution are well represented. The model has been used to derive the total CH4 emission source, being about 600 Tg yr(-1). Based on published results of isotope measurements the total contribution of fossil fuel related CHI emissions has been estimated to be about 110 Tg yr(-1). However, the individual coal, natural gas and oil associated CH4 emissions can not be accurately quantified. In particular natural gas and oil associated emissions remain speculative. Since the total anthropogenic CH4 source is about 410 Tg yr(-1) (similar to 70% of the total source) and the mean recent atmospheric CH4 increase is similar to 20 Tg yr(-1) an anthropogenic source reduction of 5% could stabilize the atmospheric CH4 level. We have calculated the indirect chemical effects of increasing CH4 on climate forcing on the basis of global 3D chemistry-transport and radiative transfer calculations. These indicate an enhancement of the direct radiative effect by about 30%, in agreement with previous work The contribution of CH4 (direct and indirect effects) to climate forcing during the past 150 years is 0.57 W m(-2) (direct 0.44 W m(-2), indirect 0.13 W m(-2)). This is about 35% of the climate forcing by CO2 (1.6 W m(-2)) and about 22% of the forcing by all long-lived greenhouse gases (2.6 W m(-2)). Scenario calculations (IPCC-IS92a) indicate that the CH4 lifetime in the atmosphere increased by about 25-30% during the past 150 years to a current value of 7.9 years. Future lifetime changes are expected to be much smaller, about 6%, mostly due to the expected increase of tropospheric O-3 (-->OH) in the tropics. The global mean concentration of CH4 may increase to about 2.55 mu mol/mol, its lifetime is expected to increase to 8.4 years in the year 2050. Further, we have calculated a CH4 global warming potential (GWP) of 21 (kgCH(4)/kgCO(2)) over a time horizon of 100 years, in agreement with IPCC (1996). Scenario calculations indicate that the importance of the climate forcing by CH4 (including indirect effects) relative to that of CO2 will decrease in future; currently this is about 35%, while this is expected to decrease to about 15% in the year 2050.