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Simulated 21st century's increase in oceanic suboxia by CO 2 ‐enhanced biotic carbon export
Author(s) -
Oschlies Andreas,
Schulz Kai G.,
Riebesell Ulf,
Schmittner Andreas
Publication year - 2008
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2007gb003147
Subject(s) - biogeochemical cycle , environmental science , carbon cycle , oceanography , biogeochemistry , nutrient , atmospheric carbon cycle , mesocosm , carbon fibers , biological pump , effects of global warming on oceans , ocean acidification , ecosystem , global warming , climate change , environmental chemistry , ecology , chemistry , geology , biology , materials science , composite number , composite material
The primary impacts of anthropogenic CO 2 emissions on marine biogeochemical cycles predicted so far include ocean acidification, global warming induced shifts in biogeographical provinces, and a possible negative feedback on atmospheric CO 2 levels by CO 2 ‐fertilized biological production. Here we report a new potentially significant impact on the oxygen‐minimum zones of the tropical oceans. Using a model of global climate, ocean circulation, and biogeochemical cycling, we extrapolate mesocosm‐derived experimental findings of a p CO 2 ‐sensitive increase in biotic carbon‐to‐nitrogen drawdown to the global ocean. For a simulation run from the onset of the industrial revolution until A.D. 2100 under a “business‐as‐usual” scenario for anthropogenic CO 2 emissions, our model predicts a negative feedback on atmospheric CO 2 levels, which amounts to 34 Gt C by the end of this century. While this represents a small alteration of the anthropogenic perturbation of the carbon cycle, the model results reveal a dramatic 50% increase in the suboxic water volume by the end of this century in response to the respiration of excess organic carbon formed at higher CO 2 levels. This is a significant expansion of the marine “dead zones” with severe implications not only for all higher life forms but also for oxygen‐sensitive nutrient recycling and, hence, for oceanic nutrient inventories.