title: A 0.5-million-year record of millennial-scale climate variability in the north atlantic
abstract: Long, continuous, marine sediment records from the subpolar North Atlantic document the glacial modulation of regional climate instability throughout the past 0.5 million years. Whenever ice sheet size surpasses a critical threshold indicated by the benthic oxygen isotope (delta18O) value of 3.5 per mil during each of the past five glaciation cycles, indicators of iceberg discharge and sea-surface temperature display dramatically larger amplitudes of millennial-scale variability than when ice sheets are small. Sea-surface temperature oscillations of 1 degrees to 2 degreesC increase in size to approximately 4 degrees to 6 degreesC, and catastrophic iceberg discharges begin alternating repeatedly with brief quiescent intervals. The glacial growth associated with this amplification threshold represents a relatively small departure from the modern ice sheet configuration and sea level. Instability characterizes nearly all observed climate states, with the exception of a limited range of baseline conditions that includes the current Holocene interglacial.
authors.affiliation: Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. Salem State College, Salem, MA 01970, USA.
authors.initials: JF
authors.lastname: McManus
authors.initials: DW
authors.lastname: Oppo
authors.initials: JL
authors.lastname: Cullen