Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scale
<p>As a major sink for anthropogenic carbon, the oceans slow the increase in carbon dioxide in the atmosphere and regulate climate change. Future changes in the ocean carbon sink, and its uncertainty at a global and regional scale, are key to understanding the future evolution of the climate....
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-04-01
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| Series: | Earth System Dynamics |
| Online Access: | https://esd.copernicus.org/articles/14/383/2023/esd-14-383-2023.pdf |
| _version_ | 1827969358434926592 |
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| author | P. Gooya N. C. Swart N. C. Swart R. C. Hamme |
| author_facet | P. Gooya N. C. Swart N. C. Swart R. C. Hamme |
| author_sort | P. Gooya |
| collection | DOAJ |
| description | <p>As a major sink for anthropogenic carbon, the oceans slow the
increase in carbon dioxide in the atmosphere and regulate climate change.
Future changes in the ocean carbon sink, and its uncertainty at a global and
regional scale, are key to understanding the future evolution of the
climate. Here we report on the changes and uncertainties in the historical
and future ocean carbon sink using output from the Coupled Model
Intercomparison Project Phase 6 (CMIP6) multi-model ensemble and compare to
an observation-based product. We show that future changes in the ocean
carbon sink are concentrated in highly active regions – 70 % of the
total sink occurs in less than 40 % of the global ocean. High pattern
correlations between the historical uptake and projected future changes in
the carbon sink indicate that future uptake will largely continue to occur
in historically important regions. We conduct a detailed breakdown of the
sources of uncertainty in the future carbon sink by region. Consistent with
CMIP5 models, scenario uncertainty dominates at the global scale, followed
by model uncertainty and then internal variability. We demonstrate how the
importance of internal variability increases moving to smaller spatial
scales and go on to show how the breakdown between scenario, model, and
internal variability changes between different ocean regions, governed by
different processes. Using the CanESM5 large ensemble we show that internal
variability changes with time based on the scenario, breaking the widely
employed assumption of stationarity. As with the mean sink, we show that
uncertainty in the future ocean carbon sink is also concentrated in the
known regions of historical uptake. Patterns in the signal-to-noise ratio
have implications for observational detectability and time of emergence,
which we show to vary both in space and with scenario. We show that the
largest variations in emergence time across scenarios occur in regions where
the ocean sink is less sensitive to forcing – outside of the highly active
regions. In agreement with CMIP5 studies, our results suggest that for a
better chance of early detection of changes in the ocean carbon sink and to
efficiently reduce uncertainty in future carbon uptake, highly active
regions, including the northwestern Atlantic and the Southern Ocean, should
receive additional focus for modeling and observational efforts.</p> |
| first_indexed | 2024-04-09T18:36:35Z |
| format | Article |
| id | doaj.art-a81250956c7a4682b9e3923408a1dbcc |
| institution | Directory Open Access Journal |
| issn | 2190-4979 2190-4987 |
| language | English |
| last_indexed | 2024-04-09T18:36:35Z |
| publishDate | 2023-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth System Dynamics |
| spelling | doaj.art-a81250956c7a4682b9e3923408a1dbcc2023-04-11T09:13:27ZengCopernicus PublicationsEarth System Dynamics2190-49792190-49872023-04-011438339810.5194/esd-14-383-2023Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scaleP. Gooya0N. C. Swart1N. C. Swart2R. C. Hamme3School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, V8P 5C2, CanadaSchool of Earth and Ocean Sciences, University of Victoria, Victoria, BC, V8P 5C2, CanadaCanadian Centre for Climate Modelling and Analysis, Environment and Climate Change Canada, Victoria, BC, V8W 2P2, CanadaSchool of Earth and Ocean Sciences, University of Victoria, Victoria, BC, V8P 5C2, Canada<p>As a major sink for anthropogenic carbon, the oceans slow the increase in carbon dioxide in the atmosphere and regulate climate change. Future changes in the ocean carbon sink, and its uncertainty at a global and regional scale, are key to understanding the future evolution of the climate. Here we report on the changes and uncertainties in the historical and future ocean carbon sink using output from the Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model ensemble and compare to an observation-based product. We show that future changes in the ocean carbon sink are concentrated in highly active regions – 70 % of the total sink occurs in less than 40 % of the global ocean. High pattern correlations between the historical uptake and projected future changes in the carbon sink indicate that future uptake will largely continue to occur in historically important regions. We conduct a detailed breakdown of the sources of uncertainty in the future carbon sink by region. Consistent with CMIP5 models, scenario uncertainty dominates at the global scale, followed by model uncertainty and then internal variability. We demonstrate how the importance of internal variability increases moving to smaller spatial scales and go on to show how the breakdown between scenario, model, and internal variability changes between different ocean regions, governed by different processes. Using the CanESM5 large ensemble we show that internal variability changes with time based on the scenario, breaking the widely employed assumption of stationarity. As with the mean sink, we show that uncertainty in the future ocean carbon sink is also concentrated in the known regions of historical uptake. Patterns in the signal-to-noise ratio have implications for observational detectability and time of emergence, which we show to vary both in space and with scenario. We show that the largest variations in emergence time across scenarios occur in regions where the ocean sink is less sensitive to forcing – outside of the highly active regions. In agreement with CMIP5 studies, our results suggest that for a better chance of early detection of changes in the ocean carbon sink and to efficiently reduce uncertainty in future carbon uptake, highly active regions, including the northwestern Atlantic and the Southern Ocean, should receive additional focus for modeling and observational efforts.</p>https://esd.copernicus.org/articles/14/383/2023/esd-14-383-2023.pdf |
| spellingShingle | P. Gooya N. C. Swart N. C. Swart R. C. Hamme Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scale Earth System Dynamics |
| title | Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scale |
| title_full | Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scale |
| title_fullStr | Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scale |
| title_full_unstemmed | Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scale |
| title_short | Time-varying changes and uncertainties in the CMIP6 ocean carbon sink from global to local scale |
| title_sort | time varying changes and uncertainties in the cmip6 ocean carbon sink from global to local scale |
| url | https://esd.copernicus.org/articles/14/383/2023/esd-14-383-2023.pdf |
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