在最后一个冰河时期燃烧生物质的突然变化
Ben Riddell-Young1,2, James Edward Lee3, Edward J Brook4
1College of Earth, Ocean, and Atmospheric Sciences (CEOAS), Oregon State University, Corvallis, OR, USA. Benjamin.riddell-young@noaa.gov.
Nature
|January 1, 2025
概括
过去冰河时期的甲 (CH4) 变化是由野火活动增加所驱动的,这与气候的急剧变化有关. 这项研究使用冰核同位素揭示了大气中二氧化碳含量增加的甲排放.
科学领域:
- 古气候学
- 大气化学
- 陆地生物地质化学
背景情况:
- 大气中甲 (CH4) 的变化对于了解过去的气候动态和碳循环至关重要.
- 冰芯记录显示了与丹斯加德-奥什格 (Dansgaard-Oeschger) 和海因里希 (Heinrich) 等突发气候事件相关的快速CH4波动.
- 这些CH4变化的确切驱动因素尚不清楚,需要同位素分析.
研究的目的:
- 调查在最后一个冰川时期大气中突然发生的CH4变化的原因.
- 通过稳定同位素测量来限制CH4变异的来源.
- 将CH4排放与突然气候变化及其对碳循环的影响联系起来.
主要方法:
- 在南极冰芯 (WAIS Divide 和 Talos Dome) 中测量稳定同位素 (δ13C-CH4 和 δD-CH4).
- 在DO和HE事件中与CH4脉冲同步的同位素转移的分析.
- 应用盒式模型来解释同位素数据并推断排放源的变化.
主要成果:
- 观察到与HE CH4脉冲同步的 δ13C-CH4的突发缩.
- 在13C-CH4中观察到突如其来的~0.5‰丰富与DO CH4的增加同步.
- 突发的CH4变化对δD-CH4的最小变化,表明微生物或地质来源的变化有限.
结论:
- 在高温和低温事件中突然的热带降雨转移可能会使13C丰富的燃烧性CH4排放增加90-150%,这表明全球野火范围增加.
- 这些燃烧导致的CH4排放可能占与高温相关的CO2突然增加的三分之一.
- 随着过去的突然气候变化, 火灾制度和地球碳循环显然发生了变化.
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