• DOI:10.1126/science.1168909
• Corpus ID: 21979910

14CH4 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources

@article{Petrenko200914CH4MI,
  title={14CH4 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources},
  author={V. V. Petrenko and Andrew M. Smith and Edward J. Brook and David C. Lowe and Katja Riedel and Gordon W. Brailsford and Quan Hua and Hinrich Schaefer and Niels Reeh and Ray F. Weiss and David M. Etheridge and Jeffrey P. Severinghaus},
  journal={Science},
  year={2009},
  volume={324},
  pages={506 - 508}
}

• V. Petrenko, Andrew M. Smith, +9 authors J. Severinghaus
• Published 24 April 2009
• Environmental Science
• Science

Radiocarbon measurements show that wetlands were responsible for the rapid increase of atmospheric methane concentration during the last deglaciation. Methane from Wetlands At the end of the cold climate interval called the Younger Dryas, approximately 11,600 years ago, global temperatures began their final ascent to the warmth of the Holocene, and the concentration of methane in the atmosphere increased rapidly and substantially. There has been much speculation about the cause of that increase, with most recent evidence pointing to wetlands as the source. The most direct proof of that explanation requires the measurement of the radiocarbon content of that methane. Petrenko et al. (p. 506; see the Perspective by Nisbet and Chappellaz) analyzed 1000 kilogramsized samples of Greenland ice, which have sufficient methane to allow measurement of its 14C content. They show that wetland sources indeed must have been responsible for the majority of the rise in atmospheric methane levels at the end of the Younger Dryas. The cause of a large increase of atmospheric methane concentration during the Younger Dryas–Preboreal abrupt climatic transition (~11,600 years ago) has been the subject of much debate. The carbon-14 (14C) content of methane (14CH4) should distinguish between wetland and clathrate contributions to this increase. We present measurements of 14CH4 in glacial ice, targeting this transition, performed by using ice samples obtained from an ablation site in west Greenland. Measured 14CH4 values were higher than predicted under any scenario. Sample 14CH4 appears to be elevated by direct cosmogenic 14C production in ice. 14C of CO was measured to better understand this process and correct the sample 14CH4. Corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas–Preboreal CH4 rise.