Oceanic sink changes

Glob. Biogeochem. Cycles http://doi.org/7hk (2015)

The North Atlantic is one of the world's most important ocean carbon sinks, which partly mitigate climate change. However the efficiency of CO₂ uptake is expected to be reduced by changes in circulation and biological processes, although the magnitude of their effect is unclear.

Nadine Goris, from the University of Bergen, and Bjerknes Centre for Climate Research, Norway, and colleagues showed that decreasing biological activity is the main reason for the warming-induced reduction in this carbon sink. They compared two model simulations from 1850–2099 (one with warming due to increases in atmospheric CO₂ included, and one without) to explore the biological, chemical and physical drivers of carbon uptake in the North Atlantic.

Under warming, biological production decreased CO₂ uptake while ocean circulation had the opposite effect, but the extent to which these processes counteracted each other differed by regions. A more pronounced reduction in biological activity in the subpolar region resulted in a decrease in CO₂ uptake (∼8 PgC) twice as large as the subtropical North Atlantic (∼4 PgC).

To better understand the effects of climate change on the ocean carbon cycle and its implications we must improve our limited knowledge of biological production in the oceans.