Stronger carbon uptake by the ocean in eddy-resolving simulations of
global warming
Abstract
Today, the ocean absorbs ~25% of the human-induced
carbon emissions. Earth System Models (ESMs) indicate that the
absorption increases by 0.79±0.07PgC per ppm of atmospheric CO2 increase
(carbon-concentration feedback), but diminishes by -17.3±5.5PgC per
degree of warming (carbon-climate feedback). Due to limited
computational capacity, ESMs parameterize flows at scales smaller than
their horizontal grid resolution, typically ~1°. We
conduct simulations of global warming using increasingly finer
horizontal resolutions (from 1° to 1/27°), with an ocean-biogeochemical
model, in an idealized mid-latitude double-gyre circulation. Our
findings demonstrate that these ocean carbon cycle feedbacks are highly
influenced by resolution. This sensitivity primarily stems from how the
overturning circulation’s mean state depends on resolution, as well as
how it responds to global warming. Although being a fraction of the
intricate response to climate change, it emphasizes the significance of
an accurate representation of small-scale ocean processes to better
constrain the future ocean carbon uptake.