Quantifying the influence of CO<sub>2</sub> seasonality on future aragonite undersaturation onset
Ocean acidification is a predictable consequence of rising atmospheric carbon dioxide (CO<sub>2</sub>), and is highly likely to impact the entire marine ecosystem – from plankton at the base of the food chain to fish at the top. Factors which are expected to be impacted include reproduct...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-10-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/12/6017/2015/bg-12-6017-2015.pdf |
| Summary: | Ocean acidification is a predictable consequence of rising atmospheric
carbon dioxide (CO<sub>2</sub>), and is highly likely to impact the entire marine
ecosystem – from plankton at the base of the food chain to fish at the top.
Factors which are expected to be impacted include reproductive health,
organism growth and species composition and distribution. Predicting when
critical threshold values will be reached is crucial for projecting the
future health of marine ecosystems and for marine resources planning and
management. The impacts of ocean acidification will be first felt at the
seasonal scale, however our understanding how seasonal variability will
influence rates of future ocean acidification remains poorly constrained due
to current model and data limitations. To address this issue, we first
quantified the seasonal cycle of aragonite saturation state utilizing new
data-based estimates of global ocean-surface dissolved inorganic carbon and
alkalinity. This seasonality was then combined with earth system model
projections under different emissions scenarios (representative concentration pathways; RCPs 2.6, 4.5 and 8.5) to
provide new insights into future aragonite undersaturation onset. Under a
high emissions scenario (RCP 8.5), our results suggest accounting for
seasonality will bring forward the initial onset of month-long
undersaturation by 17 ± 10 years compared to annual-mean estimates,
with differences extending up to 35 ± 16 years in the North Pacific due
to strong regional seasonality. This earlier onset will result in
large-scale undersaturation once atmospheric CO<sub>2</sub> reaches 496 ppm in the
North Pacific and 511 ppm in the Southern Ocean, independent of emission
scenario. This work suggests accounting for seasonality is critical to
projecting the future impacts of ocean acidification on the marine
environment. |
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| ISSN: | 1726-4170 1726-4189 |