Researchers report estimates of global preindustrial biomass burning. Biomass burning affects the climate through changes in greenhouse gases, atmospheric aerosols, surface albedo, and atmospheric chemistry. How modern fire activity compares with fire activity in the preindustrial era and the extent of human impact on fire activity remain unclear due to inconsistencies between different records. Melinda Nicewonger and colleagues reconstructed emissions from biomass burning over the past millennium based on measurements of ethane, which results from biomass burning, in ice cores. In ice cores from both Greenland and Antarctica, ethane levels were highest during the medieval period (MP, 1000-1500 CE) and lowest during the Little Ice Age (LIA, 1600-1800 CE). The observed variation in ethane levels was consistent with simulations based on an atmospheric model, in which biomass burning emissions decreased 30-45% between the MP and LIA. Such a decrease is consistent with existing ice core methane records, but not with carbon monoxide or sedimentary charcoal records. Estimated emissions from biomass burning during the MP were higher than modern levels. The decrease in biomass burning correlates with climate cooling between the MP and the LIA, suggesting that biomass burning is sensitive to climate, according to the authors.
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Article #18-07172: "Large changes in biomass burning over the last millennium inferred from paleoatmospheric ethane in polar ice cores," by Melinda R. Nicewonger, Murat Aydin, Michael J. Prather, and Eric S. Saltzman.
MEDIA CONTACT: Melinda R. Nicewonger, University of California, Irvine, CA; tel: 949-824-1726, 281-814-8046; e-mail: nicewonm@uci.edu