17. December 2010 08:50
Fire and ice: unexpected trends in burning biomass revealed by ice cores
Strasbourg, 17 December 2010 - An investigation of Antarctic ice cores has uncovered evidence that challenges the common misconception that levels of biomass burning - the consumption of wood, peat and other materials in wildfires, cooking fires and communal fires - are higher today than in the past. The findings show large variations in the levels of vegetation fires in the southern hemisphere over the last 650 years, and are published in the journal Science.
The record mainly focuses on carbon monoxide (CO) and is signifcantly different from the record in the northern hemisphere, suggesting changes may be necessary for several leading climate models.
In this study, scientists from the French Centre National de la Recherche Scientifique (CNRS) and Stony Brook University in the US used a new analytical technique to probe the levels of CO found in bubbles of ancient air trapped within ice cores drilled in the Antarctic's vast ice sheet.
"Combined with concentration measurements of CO, this record allows us to constrain the relative strength of biomass burning activity over the 650-year period in the Southern Hemisphere," said co-author and research lead John Mak, a geoscientist at Stony Brook University.
"What we find is that the amount of biomass burning has changed significantly over that time period," Mak added, "and that biomass burning was in fact a significant source of CO during pre-industrial times."
The biomass burning trends indicated by the CO largely agree with Southern Hemisphere records tracking charcoal particles in sediments and with measurements of methane from trapped ice.
Unexpectedly, the researchers found that biomass burning appears to have been more prevalent 100 to 150 years ago than it was during the 20th century.
"While this is consistent with previous findings," added Mak, "there is still a common mis-perception that biomass burning rates are much higher today than in the past. This is significant since many researchers assume that human-induced biomass burning is much greater than 'naturally' occurring biomass burning. While this may still be the case - there were people around in the 18th century - the fact that today's rates of Southern Hemisphere biomass burning seem to be lower than one to two centuries ago calls for a re-evaluation of sources."
The research was supported in part by the EUROCORES programme EUROCLIMATE ('Climate variability and (past, present and future) carbon cycle') managed by the European Science Foundation (ESF). EUROCORES received support from the EU under the Sixth Framework Programme (FP6).
Notes to Editors
The full reference for the paper is: Z. Wang, J. Chappellaz, K. Park, J.E. Mak, "Large variations in Southern Hemisphere biomass burning during the last 650 years", Science 17 December 2010.
French press release available from CNRS
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The European Science Foundation (ESF) is an independent, non-governmental organisation that promotes collaboration in scientific research, funding of research and science policy across Europe. www.esf.org
EUROCORES (European Collaborative Research scheme) enables researchers in different European countries to develop collaboration in areas where international scale and scope are required for top class science in a global context. The scheme provides a flexible framework for national basic research funding and performing organisations to join forces in supporting forefront European research in and across all scientific areas. The national organisations support all aspects including scientific coordination, networking and research funding.
This research was also supported by the National Science Foundation in the US. www.nsf.gov
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