Open AccessFuture Changes in δ 13 C of Dissolved Inorganic Carbon in the Ocean
Author(s) -
Graven Heather,
Lamb Elleanor,
Blake Daisy,
Khatiwala Samar
Publication year - 2021
Publication title -
earth's future
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.641
H-Index - 39
ISSN - 2328-4277
DOI - 10.1029/2021ef002173
Subject(s) - ocean gyre , biogeochemical cycle , environmental science , carbon cycle , atmospheric sciences , carbon fibers , biosphere , ocean current , atmosphere (unit) , carbon dioxide , oceanography , climatology , subtropics , geology , chemistry , environmental chemistry , meteorology , ecology , ecosystem , geography , materials science , organic chemistry , composite number , composite material , biology
Emissions of carbon dioxide from fossil fuel combustion are reducing the ratio 13 C/ 12 C, δ 13 C, in atmospheric CO 2 and in the carbon in the ocean and terrestrial biosphere that exchanges with the atmosphere on timescales of decades to centuries. Future changes to fossil fuel emissions vary across different scenarios and may cause decreases of more than 6% in atmospheric δ 13 CO 2 between 1850 and 2100. The effects of these potential changes on the three‐dimensional distribution of δ 13 C in the ocean have not yet been investigated. Here, we use an ocean biogeochemical‐circulation model forced with a range of Shared Socioeconomic Pathway (SSP)‐based scenarios to simulate δ 13 C in ocean dissolved inorganic carbon from 1850 to 2100. In the future, vertical and horizontal δ 13 C gradients characteristic of the biological pump are reduced or reversed, relative to the preindustrial period, with the reversal occurring in higher emission scenarios. For the highest emission scenario, SSP5‐8.5, surface δ 13 C in the center of Pacific subtropical gyres falls from 2.2% in 1850 to −3.5% by 2100. In lower emission scenarios, δ 13 C in the surface ocean decreases but then rebounds. The relationship between anthropogenic carbon (C ant ) and δ 13 C in the ocean shows a larger scatter in all scenarios, suggesting that uncertainties in δ 13 C‐based estimates of C ant may increase in the future. These simulations were run with fixed physical forcing and ocean circulation, providing a baseline of predicted δ 13 C. Further work is needed to investigate the impact of climate‐carbon cycle feedbacks on ocean δ 13 C changes.