Very Strong. Atmospheric Methane Growth in the 4 Years 2014-2017: Implications for the paris Agreement
Very Strong. Atmospheric Methane Growth in the 4 Years 2014-2017: Implications for the paris Agreement
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DOI：
10.1029/2018gb006009
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发表时间：
2019-03-01
影响因子：
5.2
通讯作者：
White, J. W. C.
中科院分区：
文献类型：
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作者：
Nisbet, E. G.;Manning, M. R.;White, J. W. C.
大气甲烷在2014年（12.7 +/- 0.5 ppb/年）、2015年（10.1 +/- 0.7 ppb/年）、2016年（7.0 +/- 0.7 ppb/年）和2017年（7.7 +/- 0.7 ppb/年）增长非常迅速，自20世纪80年代以来没有观察到这种增长率。甲烷负担的增加始于2007年，远程地面背景空气中的平均全球摩尔分数从2006年的约1，775 ppb上升到2017年的1，850 ppb。与此同时，C-13/（12）C同位素比率（以δ（13）C-CH 4表示）已经发生了变化，现在已经出现了十多年的负趋势。因此，甲烷最近摩尔分数增加的原因要么是生物源、生热和热解源排放的相对比例（和总量）发生变化，特别是在热带和亚热带地区，要么是甲烷大气汇的下降，或者两者兼而有之。遗憾的是，由于测量数据集有限，目前还不可能更加确定。过去十年中观测到的甲烷增加对气候变暖的影响，如果在未来几十年中继续以>5 ppb/年的速度增加，就足以挑战要求大幅削减大气甲烷负担的《巴黎协定》。然而，由于人为排放的甲烷量相对较大，因此，为了实现巴黎协定的目标，必须尽快实现减排目标。简明扼要大气中的甲烷（CH 4）从2007年开始上升，在过去4年中呈加速趋势。这种增长是世界性的，特别是在热带和北方中纬度地区。随着甲烷含量的上升，甲烷的碳同位素比率也发生了变化。上升的原因尚未完全了解，可能包括排放量增加，也许是空气中甲烷破坏的减少。在符合《巴黎协定》目标的未来温室气体情景中，甲烷自2007年以来的增长是不可预期的，如果继续以同样的速度增长，实现《巴黎协定》目标可能会变得非常困难。现在迫切需要减少甲烷排放，特别是化石燃料工业的甲烷排放。
Atmospheric methane grew very rapidly in 2014 (12.7 +/- 0.5 ppb/year), 2015 (10.1 +/- 0.7 ppb/year), 2016 (7.0 +/- 0.7 ppb/year), and 2017 (7.7 +/- 0.7 ppb/year), at rates not observed since the 1980s. The increase in the methane burden began in 2007, with the mean global mole fraction in remote surface background air rising from about 1,775 ppb in 2006 to 1,850 ppb in 2017. Simultaneously the C-13/(12) C isotopic ratio (expressed as delta(13) C-CH4) has shifted, has shifted, now trending negative for more than a decade. The causes of methane's recent mole fraction increase are therefore either a change in the relative proportions (and totals) of emissions from biogenic and thermogenic and pyrogenic sources, especially in the tropics and subtropics, or a decline in the atmospheric sink of methane, or both. Unfortunately, with limited measurement data sets, it is not currently possible to be more definitive. The climate warming impact of the observed methane increase over the past decade, if continued at >5 ppb/year in the coming decades, is sufficient to challenge the Paris Agreement, which requires sharp cuts in the atmospheric methane burden. However, anthropogenic methane emissions are relatively very large and thus offer attractive targets for rapid reduction, which are essential if the Paris Agreement aims are to be attained.Plain Language Summary The rise in atmospheric methane (CH4), which began in 2007, accelerated in the past 4 years. The growth has been worldwide, especially in the tropics and northern midlatitudes. With the rise has come a shift in the carbon isotope ratio of the methane. The causes of the rise are not fully understood, and may include increased emissions and perhaps a decline in the destruction of methane in the air. Methane's increase since 2007 was not expected in future greenhouse gas scenarios compliant with the targets of the Paris Agreement, and if the increase continues at the same rates it may become very difficult to meet the Paris goals. There is now urgent need to reduce methane emissions, especially from the fossil fuel industry.