Morgenstern Olaf, Moss Rowena, Manning Martin, Zeng Guang, Schaefer Hinrich, Usoskin Ilya, Turnbull Jocelyn, Brailsford Gordon, Nichol Sylvia, Bromley Tony
National Institute of Water and Atmospheric Research (NIWA), 301 Evans Bay Parade, Wellington, 6021, New Zealand.
School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.
Nat Commun. 2025 Jan 2;16(1):249. doi: 10.1038/s41467-024-55603-1.
Hydroxyl (OH) is the atmosphere's main oxidant removing most pollutants including methane. Its short lifetime prevents large-scale direct observational quantification. Abundances inferred using anthropogenic trace gas measurements and models yield conflicting trend estimates. By contrast, radiocarbon monoxide (CO), produced naturally by cosmic rays and almost exclusively removed by OH, is a tracer with a well-understood source. Here we show that Southern-Hemisphere CO measurements indicate increasing OH. New Zealand CO data exhibit an annual-mean decrease of 12 ± 2% since 1997, whereas Antarctic measurements show a December-January decrease of 43 ± 24%. Both imply similar OH increases, corroborating our own and other model results suggesting that OH has been globally increasing during recent decades. Model sensitivity simulations illustrate the roles of methane, nitrogen oxides, stratospheric ozone depletion, and global warming driving these trends. They have substantial implications for the budgets of pollutants removed by OH, and especially imply larger than documented methane emission increases.
羟基（OH）是大气中的主要氧化剂，能去除包括甲烷在内的大多数污染物。其寿命较短，阻碍了大规模直接观测量化。利用人为痕量气体测量和模型推断出的丰度得出了相互矛盾的趋势估计值。相比之下，由宇宙射线自然产生且几乎完全由羟基去除的放射性一氧化碳（CO）是一种来源明确的示踪剂。在此我们表明，南半球一氧化碳测量结果显示羟基在增加。自1997年以来，新西兰的一氧化碳数据显示年平均值下降了12±2%，而南极的测量结果显示12月至1月下降了43±24%。两者都意味着类似的羟基增加，证实了我们自己以及其他模型的结果，即近几十年来全球羟基一直在增加。模型敏感性模拟说明了甲烷、氮氧化物、平流层臭氧消耗和全球变暖在推动这些趋势中所起的作用。它们对羟基去除的污染物预算有重大影响，尤其意味着甲烷排放量的增加幅度大于记录在案的情况。
