[1] Elemental carbon (EC) aerosols absorb solar radiation which results in heating of the atmosphere. Recent increases in the atmospheric burden of EC may account for $10 to 15 % of global warming. Long-term EC data, however, are sparse. We report here our measurements of annual mean atmospheric EC concentration, [EC] for 1978-1986, 1987-1996, and 1997-2005 were, 550, 225, and 62 ng m À3, respectively. We also collected $55 cm long sediment cores from West Pine Pond near Whiteface Mountain. The cores were sliced and their 210 Pb ages determined. The first (top) five slices each represented sediment deposition over 7 years and the remaining 13 years each. EC was chemically separated from the sediment samples from four cores, and its concentration in each slice was determined using the thermal optical method. from 1917from -1930from . From 1931from -1943from through 1978from -1984, the concentration decreased gradually, from 680 to 560 ng m À3. The concentrations for 1985-1991, 1992-1998, and 1999-2005 were 295, 195, and 60 ng m À3 , respectively. Model calculations for BC emissions from fossil fuel combustion for the US by Novakov et al. (2003) qualitatively reproduce the trend determined experimentally in this work.

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