Nitrous oxide emissions are enhanced in a warmer and wetter world
Nitrous oxide emissions are enhanced in a warmer and wetter world
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DOI：
10.1073/pnas.1704552114
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发表时间：
2017-11-07
影响因子：
11.1
通讯作者：
Turner, Peter A.
中科院分区：
文献类型：
--
作者：
Griffis, Timothy J.;Chen, Zichong;Turner, Peter A.
一氧化二氮（N2 O）的全球变暖潜力是二氧化碳的300倍，在100年的时间尺度上，是平流层臭氧消耗的主要重要因素。N2 O排放的气候敏感性知之甚少，这使得很难预测化肥使用和气候变化将如何影响辐射强迫和臭氧层。对美国玉米带（世界上最密集的农业区之一）内一个非常高的塔每小时6 y的N2 O混合比的分析与逆模型相结合，表明N2 O排放的年际变化很大（316 Gg N2 O-N中心点y（-1）至585 Gg N2 O-N中心点y（-1））。这意味着区域排放因子对气候高度敏感。在观测期间最温暖的年份和春季（2012年），排放因子为7.5%，几乎是以往报告的两倍。与径流和淋溶有关的间接排放占总排放量年际变化的主导地位。在目前的气候和人类氮利用趋势下，我们预测，到2050年，区域N2 O排放量将超过600 Gg N2 O-N中心点y（-1），平均而言，将对更温暖和更潮湿的条件产生强烈的正反馈。美国玉米带的这种排放趋势可能是其他农业地区N2 O排放加剧的预兆。这种反馈将对《巴黎协定》构成重大挑战，因为该协定需要大规模的一氧化二氮减排努力才能实现其目标。
Nitrous oxide (N2O) has a global warming potential that is 300 times that of carbon dioxide on a 100-y timescale, and is of major importance for stratospheric ozone depletion. The climate sensitivity of N2O emissions is poorly known, which makes it difficult to project how changing fertilizer use and climate will impact radiative forcing and the ozone layer. Analysis of 6 y of hourly N2O mixing ratios from a very tall tower within the US Corn Belt-one of the most intensive agricultural regions of the world-combined with inverse modeling, shows large interannual variability in N2O emissions (316 Gg N2O-N center dot y(-1) to 585 Gg N2O-N center dot y(-1)). This implies that the regional emission factor is highly sensitive to climate. In the warmest year and spring (2012) of the observational period, the emission factor was 7.5%, nearly double that of previous reports. Indirect emissions associated with runoff and leaching dominated the interannual variability of total emissions. Under current trends in climate and anthropogenic N use, we project a strong positive feedback to warmer and wetter conditions and unabated growth of regional N2O emissions that will exceed 600 Gg N2O-N center dot y(-1), on average, by 2050. This increasing emission trend in the US Corn Belt may represent a harbinger of intensifying N2O emissions from other agricultural regions. Such feedbacks will pose a major challenge to the Paris Agreement, which requires large N2O emission mitigation efforts to achieve its goals.