Sack Lunch Seminar (SLS)

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






Greenland ice core records show that mean annual temperature increased by 10˚C in just 20 years during the Younger Dryas – Preboreal abrupt warming event ~11,600 years ago. Ice core records also show that this remarkable event was accompanied by a rapid ~50% increase in atmospheric methane (CH4) concentration. The cause of this CH4 increase has been the subject of much debate. One major hypothesis states that the CH4 rise was driven by increased emissions from wetlands in response to the warming. Another major hypothesis states that warming-induced dissociation of massive quantities of marine CH4 clathrate drove the increase. The 14C content of CH4 (14CH4) should distinguish between wetland and clathrate contributions to the Younger Dryas – Preboreal CH4 increase. I will present measurements of 14CH4 in glacial ice, targeting this climatic transition, using ice samples obtained from an ablation site in West Greenland. The results suggest that wetland sources were likely responsible for the majority of the Younger Dryas – Preboreal CH4 rise.