Increased importance of methane reduction for a 1.5 degree target
Increased importance of methane reduction for a 1.5 degree target
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DOI：
10.1088/1748-9326/aab89c
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发表时间：
2018-05-01
影响因子：
6.7
通讯作者：
Powell, Tom
中科院分区：
文献类型：
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作者：
Collins, William J.;Webber, Christopher P.;Powell, Tom
为了理解甲烷对实现温度目标所需的碳减排水平的重要性，有必要采取一种基于过程的方法，而不是依赖于对排放的瞬时气候反应。我们表明，甲烷(CH4)的合理减排水平可以通过增加允许的碳排放，对实现巴黎气候目标的可行性产生重大影响。甲烷对臭氧(O-3)的间接影响加强了这一益处。在这里，CH4和CO2对陆地碳储量的不同影响，包括地表O-3的影响，导致了CH4缓解后允许的碳排放量的额外增加。我们发现，从现在到2100年(每ppb甲烷0.27+/-0.05 GTC)，2100甲烷浓度的变化与额外允许的累积碳排放量之间存在着简单而稳健的关系。这种关系独立于模拟的气候敏感性和精确的温度目标，尽管后来甲烷的缓解降低了它的价值，从而降低了甲烷的减少效果。在这一允许排放量的增加中，高达12%是由于地面臭氧的影响。我们的结论是，及早减少甲烷排放将显著增加将全球变暖稳定在1.5摄氏度以下的可行性，并对人类和生态系统健康产生共同好处。
To understand the importance of methane on the levels of carbon emission reductions required to achieve temperature goals, a processed-based approach is necessary rather than reliance on the transient climate response to emissions. We show that plausible levels of methane (CH4) mitigation can make a substantial difference to the feasibility of achieving the Paris climate targets through increasing the allowable carbon emissions. This benefit is enhanced by the indirect effects of CH4 on ozone (O-3). Here the differing effects of CH4 and CO2 on land carbon storage, including the effects of surface O-3, lead to an additional increase in the allowable carbon emissions with CH4 mitigation. We find a simple robust relationship between the change in the 2100 CH4 concentration and the extra allowable cumulative carbon emissions between now and 2100 (0.27 +/- 0.05 GtC per ppb CH4). This relationship is independent of modelled climate sensitivity and precise temperature target, although later mitigation of CH4 reduces its value and thus methane reduction effectiveness. Up to 12% of this increase in allowable emissions is due to the effect of surface ozone. We conclude early mitigation of CH4 emissions would significantly increase the feasibility of stabilising global warming below 1.5 degrees C, alongside having co-benefits for human and ecosystem health.