近日，北京大学彭书时团队报道了NO_x排放上升和南移维持大气CH₄平台。相关论文于2026年9月2日发表在《自然》杂志上。

甲烷在大气增长率方面表现出年代际变率。在20世纪90年代，大气甲烷增长相较于80年代有所减缓，这主要归因于人为排放的稳定或下降。相比之下，21世纪初的经济扩张导致了人为甲烷排放的增加。然而，全球监测网络并未检测到预期的大气甲烷浓度上升；相反，在1999年至2006年间几乎未观测到大气甲烷增长。针对这一甲烷平顶期，已有若干假说被提出，但其根本原因仍不明确。

研究组结合模型模拟与甲烷及其同位素观测数据，将这一平顶期归因于2000–2006年间相对于1999年羟基自由基（OH）增加了1.4±0.4%，且主要发生在热带地区。研究组发现，热带OH的增强主要受全球氮氧化物（NO_x）排放量上升及其空间分布向发展中国家和海洋转移的驱动，而这一转移又受到热带国家经济增长和与全球贸易扩张相关的航运排放增加的推动。这些变化导致2000–2006年全球甲烷损失量相对于1999年增加了2.2±0.7%，2006年则增加了3.7±1.3%；其中2000–2006年的增加量相当于同期人为甲烷排放增长量的136% [90%, 184%]，从而维持了所观测到的甲烷平顶期。

附：英文原文

Title: Atmospheric CH4 plateau sustained by NOx emission rise and southward shift

Author: Zhu, Yu, Shen, Lu, Liu, Gang, Bates, Kelvin H., Cai, Yuxin, Peng, Shushi

Issue&Volume: 2026-09-02

Abstract: Methane exhibits decadal variability in atmospheric growth rates1. During the 1990s, atmospheric methane growth slowed relative to the 1980s, largely attributed to the stabilization or decline in anthropogenic emissions2,3,4,5,6,7. By contrast, economic expansion in the early 2000s (ref.8) led to an increase in anthropogenic methane emissions9. The anticipated rise in atmospheric methane concentrations, however, was not detected by global monitoring networks1. Instead, almost no atmospheric methane growth was observed between 1999 and 2006 (ref.1). Several hypotheses have been proposed to explain this methane plateau10,11,12,13, but the underlying causes remain uncertain3. Here we combine model simulations with methane and isotopic observations and attribute the plateau to a 1.4±0.4% hydroxyl radical (OH) increase during 2000–2006 relative to 1999, mostly occurring in the tropics. We find that the tropical OH enhancement was primarily driven by a global rise and spatial redistribution of nitrogen oxides (NOx) emissions towards developing regions and the oceans, spurred by economic growth in tropical countries and increased shipping emissions linked to global trade expansion14,15. These changes led to an amplified global methane loss of 2.2±0.7% during 2000–2006 and 3.7±1.3% in 2006 relative to 1999, with the 2000–2006 enhancement equivalent to 136% [90%, 184%] of the contemporaneous anthropogenic methane emission growth, thereby sustaining the observed methane plateau.

DOI: 10.1038/s41586-026-10983-w

Source: https://www.nature.com/articles/s41586-026-10983-w