scholarly journals Climate mitigation averts corrosive acidification in the upper ocean

2021 ◽  
Author(s):  
Sarah Schlunegger ◽  
Keith Rodgers ◽  
Burke Hales ◽  
John Dunne ◽  
Masao Ishii ◽  
...  
Keyword(s):  
Euphotic Zone ◽  
Gulf Of Alaska ◽  
Global Ocean ◽  
Climate Mitigation ◽  
Large Marine Ecosystems ◽  
Surface Ocean ◽  
The North ◽  
Marine Habitats ◽  
Anthropogenic Carbon ◽  
The North Pacific

Abstract The invasion of anthropogenic carbon into the global ocean poses an existential threat to calcifying marine organisms1–4. Observations indicate that conditions corrosive to aragonite shells, unprecedented in the surface ocean, are already occurring in mesoscale upwelling features of the North Pacific2,5,6 and Southern Ocean7, and modeling experiments indicate that large volumes of the global ocean8 including the polar ocean’s surface might become corrosive to aragonite by 20304,9–13. Such changes are expected to compress important marine habitats, but the pathways by which habitat compression manifests over global scales, and their sensitivity to mitigation, remain unexplored. Using a suite of large ensemble projections from an Earth system model14,15, we assess the effectiveness of climate mitigation for averting habitat loss at the ecologically-critical horizon of the base of the ocean’s euphotic zone. We find that without mitigation, 40-42% of this sensitive horizon experiences conditions corrosive to aragonite by 2100, with moderate mitigation this reduces to 16-19%, and with aggressive mitigation to 6-7%. Mitigation has a stronger effect on the eastern relative to western domains of the northern extratropical ocean with some of the greatest benefits in the ocean’s most productive Large Marine Ecosystems, including the California Current and Gulf of Alaska. This work reveals the significant impact that mitigation efforts compatible with the Paris Agreement target of 1.5°C could have upon preserving marine habitats that are vulnerable to ocean acidification.

scholarly journals Petrobactin, a siderophore produced by Alteromonas, mediates community iron acquisition in the global ocean

2021 ◽  
Author(s):  
Lauren E. Manck ◽  
Jiwoon Park ◽  
Benjamin J. Tully ◽  
Alfonso M. Poire ◽  
Randelle M. Bundy ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Iron Acquisition ◽  
Biogeochemical Cycling ◽  
Iron Bioavailability ◽  
Siderophore Production ◽  
Global Ocean ◽  
The North ◽  
The North Pacific ◽  
Alteromonas Macleodii

AbstractIt is now widely accepted that siderophores play a role in marine iron biogeochemical cycling. However, the mechanisms by which siderophores affect the availability of iron from specific sources and the resulting significance of these processes on iron biogeochemical cycling as a whole have remained largely untested. In this study, we develop a model system for testing the effects of siderophore production on iron bioavailability using the marine copiotroph Alteromonas macleodii ATCC 27126. Through the generation of the knockout cell line ΔasbB::kmr, which lacks siderophore biosynthetic capabilities, we demonstrate that the production of the siderophore petrobactin enables the acquisition of iron from mineral sources and weaker iron-ligand complexes. Notably, the utilization of lithogenic iron, such as that from atmospheric dust, indicates a significant role for siderophores in the incorporation of new iron into marine systems. We have also detected petrobactin, a photoreactive siderophore, directly from seawater in the mid-latitudes of the North Pacific and have identified the biosynthetic pathway for petrobactin in bacterial metagenome-assembled genomes widely distributed across the global ocean. Together, these results improve our mechanistic understanding of the role of siderophore production in iron biogeochemical cycling in the marine environment wherein iron speciation, bioavailability, and residence time can be directly influenced by microbial activities.

The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

2020 ◽  
Vol 33 (6) ◽  
pp. 2111-2130
Author(s):  
Woo Geun Cheon ◽  
Jong-Seong Kug
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic ◽  
Global Ocean Circulation ◽  
The Antarctic ◽  
The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

scholarly journals Euphotic zone metabolism in the North Pacific Subtropical Gyre based on oxygen dynamics

2020 ◽  
Author(s):  
Sara Ferron ◽  
Benedetto Barone ◽  
Matthew J Church ◽  
Angelicque E. White ◽  
David M. Karl
Keyword(s):  
North Pacific ◽  
Euphotic Zone ◽  
Subtropical Gyre ◽  
North Pacific Subtropical Gyre ◽  
The North ◽  
Oxygen Dynamics ◽  
The North Pacific

The Joint Global Ocean Flux Study in the North Pacific

2002 ◽  
Vol 49 (24-25) ◽  
pp. 5297-5301 ◽  
Author(s):  
Toshiro Saino ◽  
Alexander Bychkov ◽  
Chen-Tung Arthur Chen ◽  
Paul J Harrison
Keyword(s):  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
The North Pacific

Fetal growth and the condition of pregnant northern fur seals off western North America from 1958 to 1972

1992 ◽  
Vol 70 (11) ◽  
pp. 2125-2131 ◽  
Author(s):  
Andrew W. Trites
Keyword(s):  
Body Length ◽  
Fetal Growth ◽  
Gulf Of Alaska ◽  
Condition Index ◽  
Pregnant Females ◽  
The North ◽  
Fur Seals ◽  
Northern Fur Seals ◽  
The 1960S ◽  
The North Pacific

Annual estimates of the condition of pregnant northern fur seals (Callorhinus ursinus) and the size of their fetuses were determined from over 2600 samples collected in the North Pacific from 1958 to 1972. A condition index related the observed mass of pregnant females (adjusted for fetal mass) to their predicted mass (calculated from body length). It showed that females carrying male fetuses were in poorer condition than those carrying female fetuses. It also showed that the mean condition of pregnant females improved from 1958 to 1964, but dropped sharply in 1965. Body condition remained poor until 1972, when it plunged again. Fetal mass declined throughout the 1960s, unlike body length, which changed very little. It is suggested that fetal growth, particularly mass, is a sensitive indicator of feeding conditions during the last trimester of pregnancy while pregnant females are in the Gulf of Alaska and Bering Sea. It is further speculated that the condition index for adults reflects overall feeding conditions experienced throughout the annual migration.

scholarly journals Seasonal Evolution of Aleutian Low Pressure Systems: Implications for the North Pacific Subpolar Circulation*

2009 ◽  
Vol 39 (6) ◽  
pp. 1317-1339 ◽  
Author(s):  
Robert S. Pickart ◽  
Alison M. Macdonald ◽  
G. W. K. Moore ◽  
Ian A. Renfrew ◽  
John E. Walsh ◽  
...  
Keyword(s):  
North Pacific ◽  
Lower Troposphere ◽  
Gulf Of Alaska ◽  
Low Pressure ◽  
Aleutian Low ◽  
The North ◽  
Early Fall ◽  
The Impact ◽  
The North Pacific ◽  
Low Pressure Systems

Abstract The seasonal change in the development of Aleutian low pressure systems from early fall to early winter is analyzed using a combination of meteorological reanalysis fields, satellite sea surface temperature (SST) data, and satellite wind data. The time period of the study is September–December 2002, although results are shown to be representative of the long-term climatology. Characteristics of the storms were documented as they progressed across the North Pacific, including their path, central pressure, deepening rate, and speed of translation. Clear patterns emerged. Storms tended to deepen in two distinct geographical locations—the Gulf of Alaska in early fall and the western North Pacific in late fall. In the Gulf of Alaska, a quasi-permanent “notch” in the SST distribution is argued to be of significance. The signature of the notch is imprinted in the atmosphere, resulting in a region of enhanced cyclonic potential vorticity in the lower troposphere that is conducive for storm development. Later in the season, as winter approaches and the Sea of Okhotsk becomes partially ice covered and cold, the air emanating from the Asian continent leads to enhanced baroclinicity in the region south of Kamchatka. This corresponds to enhanced storm cyclogenesis in that region. Consequently, there is a seasonal westward migration of the dominant lobe of the Aleutian low. The impact of the wind stress curl pattern resulting from these two regions of storm development on the oceanic circulation is investigated using historical hydrography. It is argued that the seasonal bimodal input of cyclonic vorticity from the wind may be partly responsible for the two distinct North Pacific subarctic gyres.

scholarly journals Quantifying the influence of CO<sub>2</sub> seasonality on future ocean acidification

2015 ◽  
Vol 12 (8) ◽  
pp. 5907-5940
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 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.

scholarly journals New Insights into Annual and Semiannual Cycles of Sea Level Pressure

2012 ◽  
Vol 140 (4) ◽  
pp. 1347-1355 ◽  
Author(s):  
Ge Chen ◽  
Chengcheng Qian ◽  
Caiyun Zhang
Keyword(s):  
Sea Level ◽  
Southern Oscillation ◽  
Global Ocean ◽  
Boreal Winter ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Dominant Feature ◽  
The One ◽  
The North Pacific

Sea level pressure (SLP) acts, on the one hand, as a “bridge parameter” to which geophysical properties at the air–sea interface (e.g., wind stress and sea surface height) are linked, and on the other hand, as an “index parameter” by which major atmospheric oscillations, including the well-known Southern Oscillation, are defined. Using 144 yr (1854–1997) of extended reconstructed SLP data, seasonal patterns of its variability are reinvestigated in detail. New features on fundamental structure of its annual and semiannual cycles are revealed in two aspects. First, the spatiotemporal patterns of yearly and half-yearly SLPs are basically determined by a network of “amphidromes,” which are surrounded by rotational variations. Fourteen cyclonic and anticyclonic annual SLP amphidromes (half each and often in pair) are found in the global ocean, while the numbers of the two types of semiannual amphidrome are 11 and 9, respectively. The second dominant feature in SLP variability is the pattern of oscillation or seesaw for both annual and semiannual components. At least eight oscillation zones are identified for the annual cycle, which can be categorized into a boreal winter mode and an austral winter mode. As for the semiannual cycle, the seesaw pattern is geographically divided into three regimes: the North Pacific regime, the North Atlantic regime, and the Southern Ocean regime. These findings serve as a new contribution to characterizing and understanding the seasonality of the global ocean–atmosphere system.

scholarly journals The global ocean circulation on a retrograde rotating earth

2011 ◽  
Vol 7 (2) ◽  
pp. 487-499 ◽  
Author(s):  
V. Kamphuis ◽  
S. E. Huisman ◽  
H. A. Dijkstra
Keyword(s):  
Ocean Circulation ◽  
Deep Water ◽  
North Pacific ◽  
Global Ocean ◽  
Freshwater Flux ◽  
Deep Water Formation ◽  
The North ◽  
Water Formation ◽  
Global Ocean Circulation ◽  
The North Pacific

Abstract. To understand the three-dimensional ocean circulation patterns that have occurred in past continental geometries, it is crucial to study the role of the present-day continental geometry and surface (wind stress and buoyancy) forcing on the present-day global ocean circulation. This circulation, often referred to as the Conveyor state, is characterised by an Atlantic Meridional Overturning Circulation (MOC) with a deep water formation at northern latitudes and the absence of such a deep water formation in the North Pacific. This MOC asymmetry is often attributed to the difference in surface freshwater flux: the Atlantic as a whole is a basin with net evaporation, while the Pacific receives net precipitation. This issue is revisited in this paper by considering the global ocean circulation on a retrograde rotating earth, computing an equilibrium state of the coupled atmosphere-ocean-land surface-sea ice model CCSM3. The Atlantic-Pacific asymmetry in surface freshwater flux is indeed reversed, but the ocean circulation pattern is not an Inverse Conveyor state (with deep water formation in the North Pacific) as there is relatively weak but intermittently strong deep water formation in the North Atlantic. Using a fully-implicit, global ocean-only model the stability properties of the Atlantic MOC on a retrograde rotating earth are also investigated, showing a similar regime of multiple equilibria as in the present-day case. These results indicate that the present-day asymmetry in surface freshwater flux is not the most important factor setting the Atlantic-Pacific salinity difference and, thereby, the asymmetry in the global MOC.

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