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A reduced estimate of the strength of the ocean's biological carbon pump
Author(s) -
Henson Stephanie A.,
Sanders Richard,
Madsen Esben,
Morris Paul J.,
Le Moigne Frédéric,
Quartly Graham D.
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl046735
Subject(s) - biological pump , carbon cycle , carbon fibers , environmental science , particulate organic carbon , total organic carbon , tracer , flux (metallurgy) , range (aeronautics) , carbon flux , atmospheric sciences , climatology , environmental chemistry , geology , phytoplankton , ecology , chemistry , materials science , biology , physics , ecosystem , composite number , composite material , organic chemistry , nutrient , nuclear physics
A major term in the global carbon cycle is the ocean's biological carbon pump which is dominated by sinking of small organic particles from the surface ocean to its interior. Several different approaches to estimating the magnitude of the pump have been used, yielding a large range of estimates. Here, we use an alternative methodology, a thorium isotope tracer, that provides direct estimates of particulate organic carbon export. A large database of thorium‐derived export measurements was compiled and extrapolated to the global scale by correlation with satellite sea surface temperature fields. Our estimates of export efficiency are significantly lower than those derived from the f ‐ratio, and we estimate global integrated carbon export as ∼5 GtC yr −1 , lower than most current estimates. The lack of consensus amongst different methodologies on the strength of the biological carbon pump emphasises that our knowledge of a major planetary carbon flux remains incomplete.