Shortcomings of the isolated abyssal reservoir model for deglacial radiocarbon changes in the mid-depth Indo-Pacific Ocean
Severely negative 14C anomalies from the mid-depth Pacific and the Arabian Sea have been taken as support for the hypothesized deglacial release of a previously isolated, extremely 14C-deplete deep ocean carbon reservoir. We report box model simulations that cast doubt on both the existence of the hypothesized deep reservoir and its ability to explain the mid-depth 14C anomalies. First, the degree of ice age isolation needed to substantially reduce the deep 14C of the deep reservoir causes anoxia and the trapping of alkalinity from CaCO3 dissolution, the latter increasing atmospheric CO2. Second, even with a completely 14C-free deep reservoir, achieving the mid-depth 14C anomalies of observed duration requires ad hoc stifling of aspects of deep circulation to prevent rapid dissipation of the anomalous 14C-free carbon to the rest of the ocean and the atmosphere. We suggest that the mid-depth anomalies do not record basin-scale 14C changes but are instead local phenomena. Copyright © 2011 by the American Geophysical Union.
Geophysical Research Letters