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Role of the marine biosphere in the global carbon cycle
Author(s) -
Longhurst Alan R.
Publication year - 1991
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1991.36.8.1507
Subject(s) - biosphere , carbon sequestration , sink (geography) , carbon cycle , environmental science , trophic level , carbon sink , interglacial , disequilibrium , climate change , biological pump , ecology , global change , ecosystem , earth science , glacial period , biology , carbon dioxide , geography , geology , medicine , paleontology , cartography , ophthalmology
The geochemical disequilibrium of our planet is due mainly to carbon sequestration by marine organisms over geological time. Changes in atmospheric CO 2 during interglacial‐glacial transitions require biological sequestration of carbon in the oceans. Nutrient‐limited export flux from new production in surface waters is the key process in this sequestration. The most common model for export flux ignores potentially important nutrient sources and export mechanisms. Export flux occurs as a result of biological processes whose complexity appears not to be accommodated by the principal classes of simulation models, this being especially true for food webs dominated by single‐celled protists whose trophic function is more dispersed than among the multicelled metazoa. The fashionable question concerning a hypothetical “missing sink” for CO 2 emissions is unanswerable because of imprecision in our knowledge of critical flux rates. This question also diverts attention from more relevant studies of how the biological pump may be perturbed by climatic consequences of CO 2 emissions. Under available scenarios for climate change, such responses may seem more likely to reinforce, rather than mitigate, the rate of increase of atmospheric CO 2 .