scholarly journals Coupled impacts of sea ice variability and North Pacific atmospheric circulation on Holocene hydroclimate in Arctic Alaska

2020 ◽  
Vol 117 (52) ◽  
pp. 33034-33042
Author(s):  
Ellie Broadman ◽  
Darrell S. Kaufman ◽  
Andrew C. G. Henderson ◽  
Irene Malmierca-Vallet ◽  
Melanie J. Leng ◽  
...  
Keyword(s):  
Sea Ice ◽  
North Pacific ◽  
Regional Climate ◽  
Coupled Model ◽  
The Arctic ◽  
Bering Strait ◽  
Aleutian Low ◽  
The North ◽  
Arctic Alaska ◽  
The North Pacific

Arctic Alaska lies at a climatological crossroads between the Arctic and North Pacific Oceans. The modern hydroclimate of the region is responding to rapidly diminishing sea ice, driven in part by changes in heat flux from the North Pacific. Paleoclimate reconstructions have improved our knowledge of Alaska’s hydroclimate, but no studies have examined Holocene sea ice, moisture, and ocean−atmosphere circulation in Arctic Alaska, limiting our understanding of the relationship between these phenomena in the past. Here we present a sedimentary diatom assemblage and diatom isotope dataset from Schrader Pond, located ∼80 km from the Arctic Ocean, which we interpret alongside synthesized regional records of Holocene hydroclimate and sea ice reduction scenarios modeled by the Hadley Centre Coupled Model Version 3 (HadCM3). The paleodata synthesis and model simulations suggest the Early and Middle Holocene in Arctic Alaska were characterized by less sea ice, a greater contribution of isotopically heavy Arctic-derived moisture, and wetter climate. In the Late Holocene, sea ice expanded and regional climate became drier. This climatic transition is coincident with a documented shift in North Pacific circulation involving the Aleutian Low at ∼4 ka, suggesting a Holocene teleconnection between the North Pacific and Arctic. The HadCM3 simulations reveal that reduced sea ice leads to a strengthened Aleutian Low shifted west, potentially increasing transport of warm North Pacific water to the Arctic through the Bering Strait. Our findings demonstrate the interconnectedness of the Arctic and North Pacific on multimillennial timescales, and are consistent with future projections of less sea ice and more precipitation in Arctic Alaska.

North Pacific Climate Response to Freshwater Forcing in the Subarctic North Atlantic: Oceanic and Atmospheric Pathways

2009 ◽  
Vol 22 (6) ◽  
pp. 1424-1445 ◽  
Author(s):  
Yuko M. Okumura ◽  
Clara Deser ◽  
Aixue Hu ◽  
Axel Timmermann ◽  
Shang-Ping Xie
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
The Arctic ◽  
Bering Strait ◽  
Aleutian Low ◽  
Freshwater Input ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific ◽  
The Last Glacial

Abstract Sudden changes of the Atlantic meridional overturning circulation (AMOC) are believed to have caused large, abrupt climate changes over many parts of the globe during the last glacial and deglacial period. This study investigates the mechanisms by which a large freshwater input to the subarctic North Atlantic and an attendant rapid weakening of the AMOC influence North Pacific climate by analyzing four different ocean–atmosphere coupled general circulation models (GCMs) under present-day or preindustrial boundary conditions. When the coupled GCMs are forced with a 1-Sv (Sv ≡ 106 m3 s−1) freshwater flux anomaly in the subarctic North Atlantic, the AMOC nearly shuts down and the North Atlantic cools significantly. The South Atlantic warms slightly, shifting the Atlantic intertropical convergence zone southward. In addition to this Atlantic ocean–atmosphere response, all of the models exhibit cooling of the North Pacific, especially along the oceanic frontal zone, consistent with paleoclimate reconstructions. The models also show deepening of the wintertime Aleutian low. Detailed analysis of one coupled GCM identifies both oceanic and atmospheric pathways from the Atlantic to the North Pacific. The oceanic teleconnection contributes a large part of the North Pacific cooling: the freshwater input to the North Atlantic raises sea level in the Arctic Ocean and reverses the Bering Strait throughflow, transporting colder, fresher water from the Arctic Ocean into the North Pacific. When the Bering Strait is closed, the cooling is greatly reduced, while the Aleutian low response is enhanced. Tropical SST anomalies in both the Atlantic and Pacific are found to be important for the equivalent barotropic response of the Aleutian low during boreal winter. The atmospheric bridge from the tropical North Atlantic is particularly important and quite sensitive to the mean state, which is poorly simulated in many coupled GCMs. The enhanced Aleutian low, in turn, cools the North Pacific by increasing surface heat fluxes and southward Ekman transport. The closure of the Bering Strait during the last glacial period suggests that the atmospheric bridge from the tropics and air–sea interaction in the North Pacific played a crucial role in the AMOC–North Pacific teleconnection.

scholarly journals Ocean–Atmosphere State Dependence of the Atmospheric Response to Arctic Sea Ice Loss

2017 ◽  
Vol 30 (5) ◽  
pp. 1537-1552 ◽  
Author(s):  
Joe M. Osborne ◽  
James A. Screen ◽  
Mat Collins
Keyword(s):  
Sea Ice ◽  
North Pacific ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
The North ◽  
Arctic Sea ◽  
Ocean Atmosphere ◽  
Arctic Sea Ice Loss ◽  
The North Pacific ◽  
Sst Anomalies

Abstract The Arctic is warming faster than the global average. This disproportionate warming—known as Arctic amplification—has caused significant local changes to the Arctic system and more uncertain remote changes across the Northern Hemisphere midlatitudes. Here, an atmospheric general circulation model (AGCM) is used to test the sensitivity of the atmospheric and surface response to Arctic sea ice loss to the phase of the Atlantic multidecadal oscillation (AMO), which varies on (multi-) decadal time scales. Four experiments are performed, combining low and high sea ice states with global sea surface temperature (SST) anomalies associated with opposite phases of the AMO. A trough–ridge–trough response to wintertime sea ice loss is seen in the Pacific–North American sector in the negative phase of the AMO. The authors propose that this is a consequence of an increased meridional temperature gradient in response to sea ice loss, just south of the climatological maximum, in the midlatitudes of the central North Pacific. This causes a southward shift in the North Pacific storm track, which strengthens the Aleutian low with circulation anomalies propagating into North America. While the climate response to sea ice loss is sensitive to AMO-related SST anomalies in the North Pacific, there is little sensitivity to larger-magnitude SST anomalies in the North Atlantic. With background ocean–atmosphere states persisting for a number of years, there is the potential to improve predictions of the impacts of Arctic sea ice loss on decadal time scales.

Anatomy of an invasion: the trans-Arctic interchange

Paleobiology ◽  
1991 ◽  
Vol 17 (3) ◽  
pp. 281-307 ◽  
Author(s):  
Geerat J. Vermeij
Keyword(s):  
North Pacific ◽  
Absolute Number ◽  
The Arctic ◽  
Bering Strait ◽  
Western Atlantic ◽  
Early Pliocene ◽  
The North ◽  
The Asymmetry ◽  
The North Pacific ◽  
Northeastern Atlantic

When the Bering Strait between Alaska and Siberia opened about 3.5 Ma during the early Pliocene, cool-temperate and polar marine species were able to move between the North Pacific and Arctic-Atlantic basins. In order to investigate the extent, pattern, and dynamics of this trans-Arctic interchange, I reviewed the Recent and fossil distributions of post-Miocene shell-bearing Mollusca in each of five northern regions: (1) the northeastern Atlantic (Lofoten Islands to the eastern entrance of the English Channel and the northern entrance of the Irish Sea), (2) northwestern Atlantic (southern Labrador to Cape Cod), (3) northeastern Pacific (Bering Strait to Puget Sound), (4) northwestern Pacific (Bering Strait to Hokkaido and the northern Sea of Japan), and (5) Arctic (areas north of the Lofoten Islands, southern Labrador, and Bering Strait).I have identified 295 molluscan species that either took part in the interchange or are descended from taxa that did. Of these, 261 are of Pacific origin, whereas only 34 are of Arctic-Atlantic origin. Various analyses of the pattern of invasion confirm earlier work, indicating that there is a strong bias in favor of species with a Pacific origin.A geographical analysis of invaders implies that, although trans-Arctic interchange contributed to a homogenization of the biotas of the northern oceans, significant barriers to dispersal exist and have existed for trans-Arctic invaders within the Arctic-Atlantic basin. Nevertheless, trans-Arctic invaders in the Atlantic have significantly broader geographical ranges than do taxa with a pre-Pliocene history in the Atlantic.Among the possible explanations for the asymmetry of trans-Arctic invasion, two hypotheses were explicitly tested. The null hypothesis of diversity states that the number of invaders from a biota is proportional to the total number of species in that biota. Estimates of Recent molluscan diversity show that the North Pacific is 1.5 to 2.7 times richer than is the Arctic-Atlantic, depending on how faunistic comparisons are made. This difference in diversity is much smaller than is the asymmetry of trans-Arctic invasion in favor of Pacific species. Rough estimates of regional Pliocene diversity suggest that differences in diversity during the Pliocene were smaller than they are in the Recent fauna. The null hypothesis was therefore rejected.The hypothesis of ecological opportunity states that the number of invaders to a region is proportional to the number of species that became extinct there. The post-Early Pliocene magnitude of extinction was lowest in the North Pacific, intermediate in the northeastern Atlantic, and probably highest in the northwestern Atlantic. The absolute number and faunistic importance of post-Early Pliocene invaders (including trans-Arctic species, as well as taxa previously confined to warm-temperate waters and western Atlantic species that previously occurred only in the eastern Atlantic) was lowest in the North Pacific, intermediate in the northeastern Atlantic, and highest in the northwestern Atlantic. Further support for the hypothesis of ecological opportunity comes from the finding that hard-bottom communities, especially those in the northwestern Atlantic, show a higher representation of molluscan species of Pacific origin, and are likely to have been more affected by climatic events, than were communities on unconsolidated sandy and muddy bottoms. Support for the hypothesis does not rule out other explanations for the observed asymmetry of trans-Arctic invasion.A preliminary study of species-level evolution within lineages of trans-Arctic invaders indicates that anagenesis and cladogenesis have been more frequent among groups with Pacific origins than among those with Atlantic origins, and that the regions within the Arctic-Atlantic basin with the highest absolute number and faunistic representation of invaders (western Atlantic and Arctic) are the regions in which speciation has been least common among the invaders. The asymmetry of invasion is therefore distinct from the asymmetry of species-level evolution of invaders in the various northern marine regions.

scholarly journals Impact of Poleward Moisture Transport from the North Pacific on the Acceleration of Sea Ice Loss in the Arctic since 2002

2017 ◽  
Vol 30 (17) ◽  
pp. 6757-6769 ◽  
Author(s):  
H. J. Lee ◽  
M. O. Kwon ◽  
S.-W. Yeh ◽  
Y.-O. Kwon ◽  
W. Park ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
North Pacific ◽  
Moisture Transport ◽  
Arctic Sea Ice ◽  
Specific Humidity ◽  
The Arctic ◽  
The North ◽  
The Arctic Ocean ◽  
The North Pacific

Abstract Arctic sea ice area (SIA) during late summer and early fall decreased substantially over the last four decades, and its decline accelerated beginning in the early 2000s. Statistical analyses of observations show that enhanced poleward moisture transport from the North Pacific to the Arctic Ocean contributed to the accelerated SIA decrease during the most recent period. As a consequence, specific humidity in the Arctic Pacific sector significantly increased along with an increase of downward longwave radiation beginning in 2002, which led to a significant acceleration in the decline of SIA in the Arctic Pacific sector. The resulting sea ice loss led to increased evaporation in the Arctic Ocean, resulting in a further increase of the specific humidity in mid-to-late fall, thus acting as a positive feedback to the sea ice loss. The overall set of processes is also found in a long control simulation of a coupled climate model.

scholarly journals The contributions of the leading modes of the North Pacific sea surface temperature variability to the Arctic sea ice depletion in recent decades

2019 ◽  
Author(s):  
Lejiang Yu ◽  
Shiyuan Zhong ◽  
Timo Vihma
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
North Pacific ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Boreal Summer ◽  
The North ◽  
Arctic Sea ◽  
Arctic Sea Ice Loss ◽  
The North Pacific

Abstract. Arctic sea ice decrease in extent in recent decades has been linked to sea surface temperature (SST) anomalies in the North Pacific Ocean. In this study, we assess the relative contributions of the two leading modes in North Pacific SST anomalies representing external forcing related to global warming and internal forcing related to Pacific Decadal Oscillation (PDO) to the Arctic sea ice loss in boreal summer and autumn. For the 1979–2017 period, the time series of the global warming and PDO modes show significant positive and negative trends, respectively. The global warming mode accounts for 44.9 % and 50.1 % of the Arctic sea ice loss in boreal summer and autumn during this period, compared to the 20.0 % and 22.2 % from the PDO mode. There is also a seasonal difference in the response of atmospheric circulations to the two modes. The PDO mode excites a wavetrain from North Pacific to the Arctic; the wavetrain is not seen in the response of atmospheric circulation to the global warming mode. Both dynamic and thermodynamic forcings work in the relationship of atmospheric circulation and sea ice anomalies.

The Astarte (Bivalvia: Astartidae) that document the earliest opening of Bering Strait

2002 ◽  
Vol 76 (2) ◽  
pp. 239-245 ◽  
Author(s):  
Louie Marincovich ◽  
Konstantin B. Barinov ◽  
Anton E. Oleinik
Keyword(s):  
New Species ◽  
Arctic Ocean ◽  
North Pacific ◽  
The Arctic ◽  
Bivalve Mollusks ◽  
Bering Strait ◽  
Marine Diatoms ◽  
The North ◽  
The Arctic Ocean ◽  
The North Pacific

The presence of the bivalve mollusks Astarte (Tridonta) borealis Schumacher and A. (T.) hopkinsi new species, in uppermost Miocene or lower Pliocene strata of the Milky River Formation on the Alaska Peninsula, southwestern Alaska, signals the earliest opening of Bering Strait. These species migrated from the Arctic Ocean into the North Pacific when the Bering Strait first flooded and, along with co-occurring marine diatoms, are primary evidence for the earliest opening of the strait, in the latest Miocene or early Pliocene. These paleogeographically important Alaskan Astarte have been cited in this context, but have not been previously illustrated or discussed.

scholarly journals Influence of North Pacific Decadal Variability on the Western Canadian Arctic over the past 700 years

2016 ◽  
Author(s):  
François Lapointe ◽  
Pierre Francus ◽  
Scott F. Lamoureux ◽  
Mathias Vuille ◽  
Jean-Philippe Jenny ◽  
...  
Keyword(s):  
Sea Ice ◽  
Positive Feedback ◽  
North Pacific ◽  
Decadal Variability ◽  
Global Climate ◽  
Regional Climate ◽  
Canadian Arctic ◽  
Summer Precipitation ◽  
The Arctic ◽  
The North

Abstract. It is well established that the Arctic strongly influences global climate through positive feedback processes (Cohen et al., 2014), one of the most effective being the sea-ice – albedo feedback (Screen et al., 2010). Understanding the region’s sensitivity to both internal and external forcings is a prerequisite to better forecast future global climate variations. Here, sedimentological evidence from an annually laminated (varved) record highlights that North Pacific climate variability has been a persistent regulator of the regional climate in the western Canadian Arctic. The varved record is negatively correlated with both the instrumental and reconstructed Pacific Decadal Oscillation (PDO) (D'arrigo et al., 2001; Gedalof et al., 2001; Macdonald et al., 2005; Mantua et al., 1997) throughout most of the last 700 years, suggesting drier conditions during high PDO phases, and vice-versa. This is in agreement with known regional teleconnections whereby the PDO is negatively and positively correlated with summer precipitation and mean sea level pressure, respectively. This pattern is also seen during the positive phase of the North Pacific Index (NPI) (Trenberth et al., 1994) in autumn. A reduced sea-ice cover during summer is observed in the region during PDO- (NPI+), as has been found during winter (Screen et al., 2016). Strongest during the autumn season, low-level southerly winds extend from the northernmost Pacific across the Bering Strait and can reach as far as the Western Canadian Arctic. These climate anomalies projecting onto the PDO- (NPI+) phase are key factors in enhancing evaporation and subsequent precipitation in this region. As projected sea-ice loss will contribute to enhanced future warming in the Arctic, future negative phases of the PDO (or NPI+) will likely act as amplifiers of this positive feedback (Screen et al., 2016).

scholarly journals Control of Bering Strait Transport by the Meridional Overturning Circulation

2020 ◽  
Vol 50 (7) ◽  
pp. 1853-1870
Author(s):  
Paola Cessi
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
North Pacific ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Bering Strait ◽  
The North ◽  
Level Difference ◽  
Sea Level Difference ◽  
The North Pacific

AbstractIt is well established that the mean transport through Bering Strait is balanced by a sea level difference between the North Pacific and the Arctic Ocean, but no mechanism has been proposed to explain this sea level difference. It is argued that the sea level difference across Bering Strait, which geostrophically balances the northward throughflow, is associated with the sea level difference between the North Pacific and the North Atlantic/Arctic. In turn, the latter difference is caused by deeper middepth isopycnals in the Indo-Pacific than in the Atlantic, especially in the northern high latitudes because there is deep water formation in the Atlantic, but not in the Pacific. Because the depth of the middepth isopycnals is associated with the dynamics of the upper branch of the meridional overturning circulation (MOC), a model is formulated that quantitatively relates the sea level difference between the North Pacific and the Arctic/North Atlantic with the wind stress in the Antarctic Circumpolar region, since this forcing powers the MOC, and with the outcropping isopycnals shared between the Northern Hemisphere and the Antarctic circumpolar region, since this controls the location of deep water formation. This implies that if the sinking associated with the MOC were to occur in the North Pacific, rather than the North Atlantic, then the Bering Strait flow would reverse. These predictions, formalized in a theoretical box model, are confirmed by a series of numerical experiments in a simplified geometry of the World Ocean, forced by steady surface wind stress, temperature, and freshwater flux.

scholarly journals Fishery management responses to climate change in the North Pacific

2009 ◽  
Vol 66 (7) ◽  
pp. 1633-1639 ◽  
Author(s):  
Diana L. Stram ◽  
Diana C. K. Evans
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
North Pacific ◽  
Fishery Management ◽  
The Arctic ◽  
Commercial Fish ◽  
The North ◽  
Ecosystem Effects ◽  
Fish And Shellfish ◽  
The North Pacific

Abstract Stram, D. L., and Evans, D. C. K. 2009. Fishery management responses to climate change in the North Pacific. – ICES Journal of Marine Science, 66: 1633–1639. In the North Pacific, warming trends, coupled with declining sea ice, raise concerns about the effects of climate change on fish populations and ecosystem dynamics. Scientists are only beginning to understand the potential feedback mechanisms that will affect everything from plankton populations to major commercial fish species distributions, yet fishery managers have a responsibility to prepare for and respond to changing fishing patterns and potential ecosystem effects. There are ways for fishery managers to be proactive, while waiting for better information to unfold. The North Pacific Fishery Management Council (Council) and the National Marine Fisheries Service have jurisdiction over offshore fisheries in Alaska, USA. Recently, the Council has undertaken risk-averse management actions, in light of uncertainty about the effects of warming trends (and loss of sea ice) and resulting changes to fishing activities in the North Pacific. The Council has assessed whether opportunities for unregulated fishing could result from changes in fish distribution, has closed the Arctic Ocean to all commercial fishing pending further research, and has established extensive area closures where fishing with bottom-trawl gear is prohibited to protect vulnerable crab habitat and to control the northern expansion of the trawl fleet into newly ice-free waters. In cases where linkages between climate variables and fish distributions can be identified, the Council is developing adaptive management measures to respond to varying distributions of fish and shellfish. Finally, the Council has also tried to re-examine existing information to gain a better understanding of climate and ecosystem effects on fishery management. The pilot Fishery Ecosystem Plan for the Aleutian Islands maps interactions among climate factors and ecosystem components and suggests indicators for the Council to monitor.

Voyaging towards the future: the brig Rurik in the North Pacific and the emerging science of the sea

2020 ◽  
pp. 1-27
Author(s):  
ALEXANDRA BEKASOVA
Keyword(s):  
North Pacific ◽  
Bering Strait ◽  
Journal Articles ◽  
Complex Interplay ◽  
Global Networks ◽  
Scientific Investigations ◽  
Knowledge Based ◽  
The North ◽  
Private Correspondence ◽  
The North Pacific

Abstract This article explores the networking activities of Count Nikolai Rumiantsev and Adam von Krusenstern, his close collaborator. The visionary Russian statesman and the celebrated navigator were deeply involved in northern exploration. They funded and organized a circumnavigating voyage by the brig Rurik in 1815–18, with the explicit goals of searching for a northern passage between Eurasia and North America and conducting a series of scientific investigations in the Bering Strait region. This private exploratory enterprise profoundly influenced the exchange of information and reconfigured both local and global networks of knowledge. Based on an analysis of private correspondence, printed accounts and journal articles related to the Rurik's expedition, this study sheds light on how this transnational network of actors emerged and functioned, and how it promoted a lively circulation of information about exploration in the Bering Strait region in the 1810s–1820s. I argue that a complex interplay of geopolitical and intellectual competition, with exchanges, collaborations and coordination among various actors (e.g. patrons, navigators, scholars, entrepreneurs and publishers), stimulated further research on the global ocean's northern spaces and laid the foundations of marine science.

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