MOLECULAR RECORD OF SECULAR SEA-SURFACE TEMPERATURE-CHANGES ON 100-YEAR TIMESCALES FOR GLACIAL TERMINATION-I, TERMINATION-II AND TERMINATION-IV

HIGH-RESOLUTION palaeoclimate records based on oxygen isotope data have provided important insights into climate variability and rates of natural climate change on about a thousand-year timescale 1-3. Little is known 4, however, about the variation of climate and of palaeoceanographic conditions throughout the Quaternary on timescales of less than 1,000 years (at frequencies far greater than those of the Milankovitch orbital cycles). Here we show that such high time resolution is possible from molecular stratigraphic studies based on 'biomarker' organic molecules (alkenones). We have sampled alkenone stratigraphic records at 70- to 200-yr intervals across glacial terminations I, II and IV in sediment cores from ODP site 658, off northwest Africa 5. Sea surface temperatures (SSTs) derived from the alkenone (U37k) index 6-8 vary rapidly beyond the range of analytical noise by up to 2.5-degrees-C in 300 yr, showing hitherto unknown cycles with about 600-yr periodicities. Some of the changes parallel similar events in the oxygen isotope stratigraphy. SST oscillations may be linked, in part, to abrupt breakdowns in Atlantic deep-water ventilation resulting from meltwater events of Quaternary glacial terminations 3,9,10.