GISP2 oxygen isotope ratios

The GISP2 oxygen isotope record, with its high-resolution detail, yields cr ucial information on past climate change. The glacial delta(18)O oscillatio ns of the GISP2 core, with their very fast onsets, are templates of a proto type oscillation of variable duration with an amplitude of 3.9 parts per th ousand. The halfway mark of the cold-warm transition is reached in 2 years; the top is reached in 50 years. The delta(18)O-time gradient of the leadin g front is about 7.8 parts per thousand per 100 yr. After reaching the top, delta(18)O slowly declines by -0.14 parts per thousand per 100 yr. The dur ation of delta(18)O decline varies from a couple of centuries for fast osci llations to about 4000 yr for slower ones. The subsequent delta(18)O downtu rn during the warm-cold transition has a delta(18)O-time gradient of -3.2 p arts per thousand per 100 yr and lasts about 80 yr. (C) 2000 University of Washington.