Rapid Seasonal Sea-Ice Retreat in the Arctic Could Be Affecting Pacific Walrus (Odobenus rosmarus divergens) Recruitment

2006 ◽  
Vol 32 (1) ◽  
pp. 98-102 ◽  
Author(s):  
Lee W. Cooper ◽  
Carin J. Ashjian ◽  
Sharon L. Smith ◽  
Louis A. Codispoti ◽  
Jacqueline M. Grebmeier ◽  
...  
Keyword(s):  
Sea Ice ◽  
The Arctic ◽  
Pacific Walrus ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
Ice Retreat ◽  
Sea Ice Retreat

scholarly journals Impacts of large-scale atmospheric circulation changes due to winter sea-ice retreat on Black Carbon transport and deposition to the Arctic

2016 ◽  
Author(s):  
Luca Pozzoli ◽  
Srdan Dobricic ◽  
Simone Russo ◽  
Elisabetta Vignati
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
Southern Oscillation ◽  
The Arctic ◽  
The North ◽  
Ice Retreat ◽  
The North Atlantic Oscillation ◽  
Sea Ice Retreat

Abstract. Winter warming and sea ice retreat observed in the Arctic in the last decades determine changes of large scale atmospheric circulation pattern that may impact as well the transport of black carbon (BC) to the Arctic and its deposition on the sea ice, with possible feedbacks on the regional and global climate forcing. In this study we developed and applied a new statistical algorithm, based on the Maximum Likelihood Estimate approach, to determine how the changes of three large scale weather patterns (the North Atlantic Oscillation, the Scandinavian Blocking, and the El Nino-Southern Oscillation), associated with winter increasing temperatures and sea ice retreat in the Arctic, impact the transport of BC to the Arctic and its deposition. We found that the three atmospheric patterns together determine a decreasing winter deposition trend of BC between 1980 and 2015 in the Eastern Arctic while they increase BC deposition in the Western Arctic. The increasing trend is mainly due to the more frequent occurrences of stable high pressure systems (atmospheric blocking) near Scandinavia favouring the transport in the lower troposphere of BC from Europe and North Atlantic directly into to the Arctic. The North Atlantic Oscillation has a smaller impact on BC deposition in the Arctic, but determines an increasing BC atmospheric load over the entire Arctic Ocean with increasing BC concentrations in the upper troposphere. The El Nino-Southern Oscillation does not influence significantly the transport and deposition of BC to the Arctic. The results show that changes in atmospheric circulation due to polar atmospheric warming and reduced winter sea ice significantly impacted BC transport and deposition. The anthropogenic emission reductions applied in the last decades were, therefore, crucial to counterbalance the most likely trend of increasing BC pollution in the Arctic.

A 14 - 0 ka record of trends and events of sea ice cover, primary production and freshwater discharge in the Beaufort Sea, Arctic Ocean

2020 ◽  
Author(s):  
Junjie Wu ◽  
Ruediger Stein ◽  
Kirsten Fahl ◽  
Nicole Syring ◽  
Jens Hefter ◽  
...  
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Beaufort Sea ◽  
Ice Cover ◽  
Sediment Flux ◽  
The Arctic ◽  
Proxy Records ◽  
Ice Retreat ◽  
Sea Ice Retreat ◽  
Natural Climate

<p>The Arctic is changing rapidly, and one of the main and most obvious features is the drastic sea-ice retreat over the past few decades. Over such time scales, observations are deficient and not long enough for deciphering the processes controlling this accelerated sea-ice retreat. Thus, high-resolution, longer-term proxy records are needed for reconstruction of natural climate variability. In this context, we applied a biomarker approach on the well-dated sediment core ARA04C/37 recovered in the southern Beaufort Sea directly off the Mackenzie River, an area that is characterized by strong seasonal variability in sea-ice cover, primary productivity and terrigenous (riverine) input. Based on our biomarker records, the Beaufort Sea region was nearly ice-free in summer during the late Deglacial to early Holocene (14 to 8 ka). During the mid-late Holocene (8 to 0 ka), a seasonal sea-ice cover developed, coinciding with a drop in both terrigenous sediment flux and primary production. Supported by multiple proxy records, two major flood events characterized by prominent maxima in sediment flux occurred near 13 and 11 ka. The former is coincident with the Younger Dryas Cooling Event probably triggered by a  freshwater outburst from the Lake Agassiz. The origin of the second (younger) one might represent a second Mackenzie flood event, coinciding with meltwater pulse IB/post-glacial flooding of the shelf and related increased coastal erosion. Here, our interpretation remains a little bit speculative, and further research is needed and also in progress.</p>

Deep-water formation and Arctic circulation under sea-ice retreat: a comparison between CMIP6 models

2021 ◽  
Author(s):  
Anais Bretones ◽  
Kerim Hestnes Nisancioglu ◽  
Mari Fjalstad Jensen
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Mixed Layer Depth ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Overturning Circulation ◽  
Ice Retreat ◽  
Meridional Overturning ◽  
Sea Ice Edge ◽  
Sea Ice Retreat

<div> <div> <div> <div> <p>While a rapid sea-ice retreat in the Arctic has become ubiquitous, the potential weakening of the Atlantic Meridional Overturning circulation (AMOC), in response to rising greenhouse gases, is still under debate. Although climate models predict a weakening of the AMOC, observations are so far inconclusive. It has been suggested that the strength and vertical extent of the AMOC responds to sea-ice retreat, as deep mixing occurs in open-ocean areas close to the sea-ice edge. Here, we investigate this hypothesis by looking at the Arctic tidional Overturning Circulation (ArMOC) and mixed-layer depth in several CMIP6 models forced with the SSP5- 8.5 scenario. For every models we find a decoupling of the ArMOC with the AMOC: while the AMOC weakens during the 21st century, the ArMOC is enhanced.</p> </div> </div> </div> </div>

scholarly journals The complex response of Arctic aerosol to sea-ice retreat

2014 ◽  
Vol 14 (14) ◽  
pp. 7543-7557 ◽  
Author(s):  
J. Browse ◽  
K. S. Carslaw ◽  
G. W. Mann ◽  
C. E. Birch ◽  
S. R. Arnold ◽  
...  
Keyword(s):  
Sea Ice ◽  
Dimethyl Sulfide ◽  
Cloud Condensation Nuclei ◽  
Arctic Sea Ice ◽  
Sea Salt ◽  
Radiative Properties ◽  
Climate Feedback ◽  
The Arctic ◽  
Ice Retreat ◽  
Sea Ice Retreat

Abstract. Loss of summertime Arctic sea ice will lead to a large increase in the emission of aerosols and precursor gases from the ocean surface. It has been suggested that these enhanced emissions will exert substantial aerosol radiative forcings, dominated by the indirect effect of aerosol on clouds. Here, we investigate the potential for these indirect forcings using a global aerosol microphysics model evaluated against aerosol observations from the Arctic Summer Cloud Ocean Study (ASCOS) campaign to examine the response of Arctic cloud condensation nuclei (CCN) to sea-ice retreat. In response to a complete loss of summer ice, we find that north of 70° N emission fluxes of sea salt, marine primary organic aerosol (OA) and dimethyl sulfide increase by a factor of ~ 10, ~ 4 and ~ 15 respectively. However, the CCN response is weak, with negative changes over the central Arctic Ocean. The weak response is due to the efficient scavenging of aerosol by extensive drizzling stratocumulus clouds. In the scavenging-dominated Arctic environment, the production of condensable vapour from oxidation of dimethyl sulfide grows particles to sizes where they can be scavenged. This loss is not sufficiently compensated by new particle formation, due to the suppression of nucleation by the large condensation sink resulting from sea-salt and primary OA emissions. Thus, our results suggest that increased aerosol emissions will not cause a climate feedback through changes in cloud microphysical and radiative properties.

scholarly journals Contributions of advection and melting processes to the decline in sea ice in the Pacific sector of the Arctic Ocean

2019 ◽  
Author(s):  
Haibo Bi ◽  
Qinghua Yang ◽  
Xi Liang ◽  
Haijun Huang
Keyword(s):  
Sea Ice ◽  
Melting Process ◽  
The Arctic ◽  
Positive Trend ◽  
Ice Coverage ◽  
The Pacific ◽  
Ice Retreat ◽  
The Mean ◽  
Sea Ice Retreat ◽  
Increasing Trends

Abstract. The Pacific–Arctic (PA) Ocean is a region sensitive to climate change. Given the alarming changes in sea ice cover during recent years, knowledge of sea ice loss with respect to ice advection and melting processes has become critical. With satellite-derived products from the National Snow and Ice Center (NSIDC), a 38-yr record (1979–2016) of the loss in sea ice area in summer within the Pacific-Arctic (PA) sector due to the two processes is obtained. The average sea ice outflow from the PA to the Atlantic-Arctic (AA) Ocean during the summer season (June–September) reaches 173 × 103 km2, which corresponds to approximately 34 % of the mean annual export (October to September). Over the investigated period, a positive trend of 4.2 × 103 km2/yr is also observed for the outflow field in summer. The mean estimate of sea ice retreat within the PA associated with summer melting is 1.66 × 106 km2, with a positive trend of 53.1 × 103 km2/yr. As a result, the increasing trends of ice retreat caused by outflow and melting together contribute to a stronger decrease in sea ice coverage within the PA (57.3 × 103 km2/yr) in summer. In percentage terms, the melting process accounts for 90.4 % of the sea ice retreat in the PA in summer, whereas the remaining 9.6 % is explained by the outflow process, on average. Moreover, our analysis suggests that the connections are relatively strong (R = 0.63), moderate (R = −0.46), and weak (R = −0.24) between retreat of sea ice and the winds associated with the Dipole Anomaly (DA), North Atlantic Oscillation (NAO), and Arctic Oscillation (AO), respectively. The DA participates by impacting both the advection (R = 0.74) and melting (R = 0.55) processes, whereas the NAO affects the melting process (R = −0.46).

Pacific walrus diet across 4000 years of changing sea ice conditions

2019 ◽  
pp. 1-17 ◽  
Author(s):  
Casey T. Clark ◽  
Lara Horstmann ◽  
Anne de Vernal ◽  
Anne M. Jensen ◽  
Nicole Misarti
Keyword(s):  
Sea Ice ◽  
Chukchi Sea ◽  
Trophic Position ◽  
Bone Collagen ◽  
Pacific Walrus ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
Trophic Changes ◽  
Primary Driver ◽  
Ice Conditions

AbstractDeclining sea ice is expected to change the Arctic's physical and biological systems in ways that are difficult to predict. This study used stable isotope compositions (δ13C and δ15N) of archaeological, historic, and modern Pacific walrus (Odobenus rosmarus divergens) bone collagen to investigate the impacts of changing sea ice conditions on walrus diet during the last ~4000 yr. An index of past sea ice conditions was generated using dinocyst-based reconstructions from three locations in the northeastern Chukchi Sea. Archaeological walrus samples were assigned to intervals of high and low sea ice, and δ13C and δ15N were compared across ice states. Mean δ13C and δ15N values were similar for archaeological walruses from intervals of high and low sea ice; however, variability among walruses was greater during low-ice intervals, possibly indicating decreased availability of preferred prey. Overall, sea ice conditions were not a primary driver of changes in walrus diet. The diet of modern walruses was not consistent with archaeological low sea ice intervals. Rather, the low average trophic position of modern walruses (primarily driven by males), with little variability among individuals, suggests that trophic changes to this Arctic ecosystem are still underway or are unprecedented in the last ~4000 yr.

scholarly journals Contributions of advection and melting processes to the decline in sea ice in the Pacific sector of the Arctic Ocean

2019 ◽  
Vol 13 (5) ◽  
pp. 1423-1439 ◽  
Author(s):  
Haibo Bi ◽  
Qinghua Yang ◽  
Xi Liang ◽  
Liang Zhang ◽  
Yunhe Wang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Melting Process ◽  
The Arctic ◽  
Positive Trend ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Ice Retreat ◽  
The Mean ◽  
Sea Ice Retreat

Abstract. The Pacific sector of the Arctic Ocean (PA, hereafter) is a region sensitive to climate change. Given the alarming changes in sea ice cover during recent years, knowledge of sea ice loss with respect to ice advection and melting processes has become critical. With satellite-derived products from the National Snow and Ice Center (NSIDC), a 38-year record (1979–2016) of the loss in sea ice area in summer within the Pacific-Arctic (PA) sector due to the two processes is obtained. The average sea ice outflow from the PA to the Atlantic-Arctic (AA) Ocean during the summer season (June–September) reaches 0.173×106 km2, which corresponds to approximately 34 % of the mean annual export (October to September). Over the investigated period, a positive trend of 0.004×106 km2 yr−1 is also observed for the outflow field in summer. The mean estimate of sea ice retreat within the PA associated with summer melting is 1.66×106 km2, with a positive trend of 0.053×106 km2 yr−1. As a result, the increasing trends of ice retreat caused by outflow and melting together contribute to a stronger decrease in sea ice coverage within the PA (0.057×106 km2 yr−1) in summer. In percentage terms, the melting process accounts for 90.4 % of the sea ice retreat in the PA in summer, whereas the remaining 9.6 % is explained by the outflow process, on average. Moreover, our analysis suggests that the connections are relatively strong (R=0.63), moderate (R=-0.46), and weak (R=-0.24) between retreat of sea ice and the winds associated with the dipole anomaly (DA), North Atlantic Oscillation (NAO), and Arctic Oscillation (AO), respectively. The DA participates by impacting both the advection (R=0.74) and melting (R=0.55) processes, whereas the NAO affects the melting process (R=-0.46).

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