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SUMMARY:Playing with fire: Ice core biomass burning records from four cont
 inents - Dr. Natalie Kehrwald\, University of Venice\, Italy
DTSTART:20130702T100000Z
DTEND:20130702T110000Z
UID:TALK45803@talks.cam.ac.uk
CONTACT:Dr. Ailsa Benton
DESCRIPTION:Aerosols continue to be one of the least understood aspects of
  the modern climate system and even less is known about their past influen
 ce. Ice cores contain specific molecular markers including levoglucosan (1
 \,6-anhydro-β-D-glucopyranose) and other pyrochemical evidence that provi
 des much-needed information on the role of fire aerosols in driving past c
 limate and the possibility of current biomass burning affecting future glo
 bal climate. In addition to climate and fire linkages\, humans have influe
 nced fire activity for thousands of years through changing fire ignition r
 ates\, fuels\, and land cover. We quantify fire proxy records from four co
 ntinents to provide an interdisciplinary synthesis of the interactions bet
 ween past fires\, human activity\, and climate change. Here\, we present l
 evoglucosan flux measured across the past 10\,000 years in the EPICA Dome 
 C ice core (7506'S\, 12321'E\, 3233 masl)\, Holocene and Eemian levo
 glucosan concentrations in the NEEM\, Greenland (7727’ N\; 513’W
 \, 2454 masl) ice core\, during the past 4000 years in the Kilimanjaro (3
 04.6’S\; 3721.2’E\, 5893 masl) ice core\, and preliminary Holoce
 ne Tibetan Plateau snow pit and ice core results. \n\nHuman activities can
  and have altered fire activity beyond background climate conditions as lo
 ng ago as the late Pleistocene and have significantly changed vegetation r
 egimes with changing agricultural and pastoral practices. Kilimanjaro levo
 glucosan concentrations peak 800 – 1000 yr BP\, coincident with the larg
 est regional droughts and associated human migration. NEEM Holocene fire a
 ctivity is highest during decadal-scale northern central Asian droughts an
 d does not demonstrate a modern rise associated with increased settlement 
 in boreal regions. EPICA Dome C results demonstrate an order of magnitude 
 increase in levoglucosan concentrations beginning approximately 500 yr BP 
 that is likely due to human activity rather than changing climate conditio
 ns. Unlike methane and its isotopic signatures\, levoglucosan is not a glo
 bally mixed marker\, and these hemispheric differences are consistent with
  the atmospheric lifetime\, sources\, and transport of levoglucosan. The E
 PICA Dome C levoglucosan profile is strikingly similar to regional charcoa
 l compilations from New Zealand and southeastern Australia\, and substanti
 ally differs from South American records. Transport models demonstrate the
  possibility of New Zealand and Australia as major levoglucosan sources to
  EPICA Dome C. These fire histories provide insight into the interplay bet
 ween climate\, human activity\, and biomass burning aerosols through time.
 \n
LOCATION:room 307\,  British Antarctic Survey\, High Cross\, Cambridge\, C
 B3 0ET
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