Does export production measure transient changes of the biological
carbon pump under global warming?
In a widely-held conception, the biological carbon pump (BCP) is equal
to the export of organic matter out of the euphotic zone. Using global
ocean-atmosphere model experiments we show that the change in export
production is a poor measure of the biological pump’s feedback to the
atmosphere. The change in global true oxygen utilization (TOU), an
integrative measure of the imprint of the biological carbon pump on
marine oxygen, however, is in good agreement with the net change in the
biogenic air-sea flux of oxygen. Since, TOU correlates very well with
apparent oxygen utilization (AOU) in our experiments, we propos to
measure the change of AOU from data of global float programs to monitor
the feedback of the BCP to the atmosphere. For the current ocean we
estimate that BCP changes lead to an uptake of CO by the ocean in the
range of 0.07 to 0.14 GtC/yr.