Changes in black carbon deposition to Antarctica from two high-resolution ice core records, 1850-2000 AD
Abstract. Refractory black carbon aerosols (rBC) emitted\nby biomass burning (fires) and fossil fuel combustion, affect\nglobal climate and atmospheric chemistry. In the Southern\nHemisphere (SH), rBC is transported in the atmosphere\nfrom low- and mid-latitudes to Antarctica and deposited to\nthe polar ice sheet preserving a history of emissions and atmospheric\ntransport. Here, we present two high-resolution\nAntarctic rBC ice core records drilled from the West Antarctic\nIce Sheet divide and Law Dome on the periphery of the\nEast Antarctic ice sheet. Separated by ⬚3500 km, the records\nspan calendar years 1850–2001 and reflect the rBC distribution\nover the Indian and Pacific ocean sectors of the Southern\nOcean. Concentrations of rBC in the ice cores displayed\nsignificant variability at annual to decadal time scales, notably\nin ENSO-QBO and AAO frequency bands. The delay\nobserved between rBC and ENSO variability suggested\nthat ENSO does not directly affect rBC transport, but rather\ncontinental hydrology, subsequent fire regimes, and aerosol\nemissions. From 1850 to 1950, the two ice core records were\nuncorrelated but were highly correlated from 1950 to 2002\n(cross-correlation coefficient at annual resolution: r = 0.54,\np < 0.01) due to a common decrease in rBC variability. The\ndecrease in ice-core rBC from the 1950s to late 1980s displays\nsimilarities with inventories of SH rBC grass fires and\nbiofuel emissions, which show reduced emission estimates\nover that period.