2025年1月1日出版的《自然》杂志发表了美国俄勒冈州立大学Riddell-Young小组的最新成果，他们的最新研究揭示了末次冰期生物质燃烧的突变。

研究人员对WAIS分水岭和Talos Dome冰芯的δ13C-CH4和δD-CH4进行了多年代际测量，研究发现，δ13C-CH4突变富集1‰与HE CH4脉冲同步，δ13C-CH4突变富集0.5‰与DO CH4增加同步。δD-CH4在CH4突变过程中变化不大。

利用箱形模型解释这些同位素变化，并假设微生物排放的δ13C-CH4恒定，研究人员认为与HEs和DO事件相关的热带降雨突变增加了富含13C的热源CH4排放，从而将全球野火范围扩大了90-150%。碳循环箱模拟实验表明，由此释放的陆地碳可能已经从与HEs相关的二氧化碳从三分之一突然增加到全部。这些发现表明，火的状态和陆地碳循环与末次冰期过去的气候突变同时发生变化。

据研究人员介绍，了解过去大气甲烷（CH4）变率的规律对于表征CH4与全球气候和陆地生物地球化学循环之间的关系具有重要意义。大气CH4的冰芯记录包含与末次冰期气候突变有关的快速变化，被称为Dansgaard-Oeschger （DO）事件和Heinrich事件。这些CH4变化的驱动因素仍然未知，但可以通过对大气CH4稳定同位素组成的冰芯测量加以限制，该测量对不同同位素可区分的排放类别（微生物、热成因和地质）的强度很敏感。

附：英文原文

Title: Abrupt changes in biomass burning during the last glacial period

Author: Riddell-Young, Ben, Lee, James Edward, Brook, Edward J., Schmitt, Jochen, Fischer, Hubertus, Bauska, Thomas K., Menking, James A., Iseli, Ren, Clark, Justin Reid

Issue&Volume: 2025-01-01

Abstract: Understanding the causes of past atmospheric methane (CH4) variability is important for characterizing the relationship between CH4, global climate and terrestrial biogeochemical cycling. Ice core records of atmospheric CH4 contain rapid variations linked to abrupt climate changes of the last glacial period known as Dansgaard–Oeschger (DO) events and Heinrich events (HE). The drivers of these CH4 variations remain unknown but can be constrained with ice core measurements of the stable isotopic composition of atmospheric CH4, which is sensitive to the strength of different isotopically distinguishable emission categories (microbial, pyrogenic and geologic). Here we present multi-decadal-scale measurements of δ13C–CH4 and δD–CH4 from the WAIS Divide and Talos Dome ice cores and identify abrupt 1‰ enrichments in δ13C–CH4 synchronous with HE CH4 pulses and 0.5‰ δ13C–CH4 enrichments synchronous with DO CH4increases. δD–CH4 varied little across the abrupt CH4 changes. Using box models to interpret these isotopic shifts6 and assuming a constant δ13C–CH4 of microbial emissions, we propose that abrupt shifts in tropical rainfall associated with HEs and DO events enhanced 13C-enriched pyrogenic CH4 emissions, and by extension global wildfire extent, by 90–150%. Carbon cycle box modelling experiments suggest that the resulting released terrestrial carbon could have caused from one-third to all of the abrupt CO2 increases associated with HEs. These findings suggest that fire regimes and the terrestrial carbon cycle varied contemporaneously and substantially with past abrupt climate changes of the last glacial period.

DOI: 10.1038/s41586-024-08363-3

Source: https://www.nature.com/articles/s41586-024-08363-3

来源：科学网  小柯机器人