The Future of Scientific Drilling in the North Pacific and Arctic

Abstract. Ocean acidification is a predictable consequence of rising atmospheric carbon dioxide (CO2), and is highly likely to impact the entire marine ecosystem – from plankton at the base 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 (RCPs 2.6, 4.5 and 8.5) to provide new insights into future aragonite under-saturation onset. Under a high emissions scenario (RCP 8.5), our results suggest accounting for seasonality will bring forward the initial onset of month-long under-saturation by 17 years compared to annual-mean estimates, with differences extending up to 35 ± 17 years in the North Pacific due to strong regional seasonality. Our results also show large-scale under-saturation once atmospheric CO2 reaches 486 ppm in the North Pacific and 511 ppm in the Southern Ocean independent of emission scenario. Our results suggest that accounting for seasonality is critical to projecting the future impacts of ocean acidification on the marine environment.

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A modelling perspective of North Pacific Intermediate water in the future

10.5194/egusphere-egu2020-22599 ◽

2020 ◽

Author(s):

Xun Gong ◽

Lars Ackermann ◽

Gerrit Lohmann

Keyword(s):

Pacific Ocean ◽

North Pacific ◽

Carbon Sink ◽

North Pacific Ocean ◽

Intermediate Water ◽

North Pacific Intermediate Water ◽

The North ◽

The Future ◽

Near Future ◽

The North Pacific

North Pacific Intermediate water (NPIW) is a dominant water mass controlling ~400-1200m depth North Pacific Ocean, characterized by its low salinities and relatively lower temperatures. In the modern climate, the interplay between NPIW-related physical and biogeochemical processes among seasons determines annual-mean budget and efficiency of carbon sink into the North Pacific Ocean. Thus, to understand the NPIW physics is key to project roles of the North Pacific Ocean in changing Earth climate and carbon systems in the future. In this study, we provide a modelling view of the NPIW history since Yr 1850 (historical experiment) and its projection to near future (IPCC-defined RCP 4.2 and 8.5 experiments until Yr 2100), using new-generation Alfred Wegener Institute Earth System Model (AWI-ESM). Our results suggest an important role of regional hydroclimate feedback over the NW Pacific and Sea of Okhotsk in determining the NPIW from recent past to near future.

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Future changes in ENSO teleconnections over the North Pacific and North America in CMIP6 simulations

10.5194/egusphere-egu2020-8916 ◽

2020 ◽

Author(s):

Jonathan Beverley ◽

Mat Collins ◽

Hugo Lambert ◽

Rob Chadwick

Keyword(s):

North America ◽

North Pacific ◽

Southern Oscillation ◽

Coupled Model ◽

Positive Temperature ◽

Temperature Anomalies ◽

The North ◽

Enso Teleconnections ◽

The Future ◽

The North Pacific

El Ni&#241;o&#8211;Southern Oscillation (ENSO) has major impacts on the weather and climate across many regions of the world. Understanding how these teleconnections may change in the future is therefore an important area of research. Here, we use simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to investigate future changes in ENSO teleconnections in the North Pacific/North America sector.Precipitation over the equatorial Pacific associated with ENSO is projected to shift eastwards under global warming as a result of greater warming in the east Pacific, which reduces the barrier to convection as the warm pool expands eastwards. As a result, there is medium confidence (IPCC AR5 report) that ENSO teleconnections will shift eastwards in the North Pacific/North America sector. In the CMIP6 models, the present day teleconnection is relatively well simulated, with most models showing an anomalously deep Aleutian low and associated positive temperature anomalies over Alaska and northern North America in El Ni&#241;o years. In the future warming simulations (we use abrupt-4xCO2, in which CO2 concentrations are immediately quadrupled from the global annual mean 1850 value), in agreement with the IPCC AR5 report, the North America teleconnection and associated circulation change is shifted eastwards in most models. However, it is also significantly weaker, with the result that the positive temperature anomalies in El Ni&#241;o years over North America are much reduced. This weakening is seen both in models with a projected increase and projected decrease in the amplitude of future El Ni&#241;o events. The mechanisms related to these projected changes, along with potential implications for future long range predictability over North America, will be discussed.

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Quantifying the influence of CO2 seasonality on future aragonite undersaturation onset

Biogeosciences ◽

10.5194/bg-12-6017-2015 ◽

2015 ◽

Vol 12 (20) ◽

pp. 6017-6031 ◽

Cited By ~ 14

Author(s):

T. P. Sasse ◽

B. I. McNeil ◽

R. J. Matear ◽

A. Lenton

Keyword(s):

Ocean Acidification ◽

North Pacific ◽

Dissolved Inorganic Carbon ◽

Marine Ecosystem ◽

Global Ocean ◽

Saturation State ◽

The North ◽

Data Limitations ◽

The Future ◽

The North Pacific

Abstract. Ocean acidification is a predictable consequence of rising atmospheric carbon dioxide (CO2), 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 CO2 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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