BIOMASS BURNING RECORD AND BLACK CARBON IN THE GISP2 ICE CORE

We have determined the black carbon concentration in three sets of ice core samples from the GISP2 (Greenland Ice Sheet Project 2) ice core. The major peaks in black carbon concentration between 320 and 330 A.D. correlate well with peaks in ammonium concentration and with the dips in electrical conductivity measurements (ECM), which allows us to identify extensive forest fires in this time period. The average black carbon concentration during the 320 to 330 A.D. decade is found to be 2.1 mu g of black carbon per 1 kg of snow melt water. The current snow (1989 and 1990) from the GISP2 site shows an average black carbon concentration of about 2.0 mu/kg suggesting that the rate of black carbon deposition at the GISP2 Greenland site during 1989-1990 was about the same as 1670 years ago.