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1605776 
Journal Article 
Productivity feedback did not terminate the Paleocene-Eocene Thermal Maximum (PETM) 
Torfstein, A; Winckler, G; Tripati, A 
2010 
Yes 
Climate of the Past
ISSN: 1814-9324
EISSN: 1814-9332 
6 
2 
265-272 
WOS:000277185200010 
The Paleocene-Eocene Thermal Maximum (PETM) occurred
approximately 55 million years ago, and is one of the most dramatic abrupt global warming events
in the geological record. This warming was triggered by the sudden release of thousands of
gigatons of carbon into the atmosphere and is widely perceived to be the best analogue for
current anthropogenic climate change. Yet, the mechanism of recovery from this event remains
controversial. A massive increase in the intensity of the marine biological pump ('productivity
feedback') has been suggested to cause a drawdown of atmospheric CO(2) and subsequent carbon
sequestration in the ocean. A re-evaluation of the 'productivity feedback hypothesis', based on
biogenic barium mass accumulation rates (Ba-MARs) for a site in the Southern Ocean, finds that
any increase in export production lagged the initial carbon release by at least similar to 70 000
years. This implies that export production did not facilitate rapid removal of excess carbon from
the atmosphere. Thus, the most likely mechanism for carbon removal appears to be silicate
weathering, which occurred at much slower rates than previously assumed.