Increased productivity in the subantarctic ocean during Heinrich events

Publication Type  Journal Article
Year of Publication  2005
Authors  Sachs, J. P.; Anderson, R. F.
Journal Title  Nature
Volume  434
Issue  7037
Pages  1118-1121
Journal Date  Apr 28
ISBN Number  0028-0836
Accession Number  ISI:000228693300040
Key Words  atmospheric co2 concentrations; ice core; thermohaline circulation; climate-change; labrador-sea; taylor dome; new-zealand; sediment; iron; kyr

Massive iceberg discharges from the Northern Hemisphere ice sheets, 'Heinrich events', coincided with the coldest periods of the last ice age(1). There is widespread evidence for Heinrich events and their profound impact on the climate and circulation of the North Atlantic Ocean, but their influence beyond that region remains uncertain(1). Here we use a combination of molecular fingerprints of algal productivity and radioisotope tracers of sedimentation to document eight periods of increased productivity in the subpolar Southern Ocean during the past 70,000 years that occurred within 1,000-2,000 years of a Northern Hemisphere Heinrich event. We discuss possible causes for such a link, including increased supply of iron from upwelling and increased stratification during the growing season, which imply an alteration of the global ocean circulation during Heinrich events. The mechanisms linking North Atlantic iceberg discharges with subantarctic productivity remain unclear at this point. We suggest that understanding how the Southern Ocean was altered during these extreme climate perturbations is critical to understanding the role of the ocean in climate change.


920MDTimes Cited:15Cited References Count:30

URL  <Go to ISI>://000228693300040
DOI  Doi 10.1038/Nature03544