Effect Of Sea Ice Loss Research Articles

Limited increases in Arctic offshore oil and gas production with climate change and the implications for energy markets

Climate change impacts on sea ice thickness is opening access to offshore Arctic resources. The degree to which these resources are exploited will depend on sea-ice conditions, technology costs, international energy markets, and the regulatory environment. We use an integrated human-Earth system model, GCAM, to explore the effects of spatial–temporal patterns of sea-ice loss under climate change on future Arctic offshore oil and gas extraction, considering interactions with global energy markets and emission reduction scenarios. We find that under SSP5, a “fossil-fueled development” scenario, the effects of sea-ice loss are larger for Arctic offshore oil production than gas. Under SSP5, future extraction of Arctic offshore oil and gas through 2100 adds roughly 0.8–2.6 EJ/year to oil and gas markets but does not have large impacts on global oil and gas markets. Surprisingly, a low-carbon scenario results in greater Arctic offshore oil production to offset the more emissions-intensive unconventional oil production.

Opposite Responses of the Dry and Moist Eddy Heat Transport Into the Arctic in the PAMIP Experiments

AbstractGiven uncertainty in the processes involved in polar amplification, elucidating the role of poleward heat and moisture transport is crucial. The Polar Amplification Model Intercomparison Project (PAMIP) permits robust separation of the effects of sea ice loss from sea surface warming under climate change. We utilize a moist isentropic circulation framework that accounts for moisture transport, condensation, and eddy transport, in order to analyze the circulation connecting the mid‐latitudes and the Arctic. In PAMIP's atmospheric general circulation model experiments, prescribed sea ice loss reduces poleward heat transport (PHT) by warming the returning moist isentropic circulation at high latitudes, while prescribed warming of the ocean surface increases PHT by strengthening the moist isentropic circulation. Inter‐model spread of PHT into the Arctic reflects the tug‐of‐war between sea‐ice and surface‐warming effects.

Memory effects of Eurasian land processes cause enhanced cooling in response to sea ice loss

Amplified Arctic warming and its relevance to mid-latitude cooling in winter have been intensively studied. Observational evidence has shown strong connections between decreasing sea ice and cooling over the Siberian/East Asian regions. However, the robustness of such connections remains a matter of discussion because modeling studies have shown divergent and controversial results. Here, we report a set of general circulation model experiments specifically designed to extract memory effects of land processes that can amplify sea ice–climate impacts. The results show that sea ice–induced cooling anomalies over the Eurasian continent are memorized in the snow amount and soil temperature fields, and they reemerge in the following winters to enhance negative Arctic Oscillation-like anomalies. The contribution from this memory effect is similar in magnitude to the direct effect of sea ice loss. The results emphasize the essential role of land processes in understanding and evaluating the Arctic–mid-latitude climate linkage.

Assessing the Role of High‐Frequency Winds and Sea Ice Loss on Arctic Phytoplankton Blooms in an Ice‐Ocean‐Biogeochemical Model

AbstractThe long‐term trend of increasing phytoplankton net primary production (NPP) in the Arctic correlates with increasing light penetration due to sea ice loss. However, recent studies suggest that enhanced stormy wind mixing may also play a significant role enhancing NPP. Here, we isolate the role of sea ice and stormy winds (hereafter high‐frequency winds) using an eddy‐permitting ice‐ocean‐biogeochemical model configured for the North Atlantic and the Arctic. In the model, the presence of high‐frequency winds stimulates nutrient upwelling by producing an earlier and longer autumn‐winter mixing period with deeper mixing layer. The early onset of autumn mixing results in nutrients being brought‐up to near‐surface waters before the light becomes the dominant limiting factor, which leads to the autumn bloom. The enhanced mixing results in higher nutrient concentrations in spring and thus a large spring bloom. The model also shows significant iron limitation in the Labrador Sea, which is intensified by high‐frequency winds. The effect of sea ice loss on NPP was found to be regionally dependent on the presence of high‐frequency winds. This numerical study suggests high‐frequency winds play significant role increasing NPP in the Arctic and sub‐Arctic by alleviating phytoplankton nutrient limitation and that the isolated effect of sea ice loss on light plays a comparatively minor role.

Survey-based assessment of the frequency and potential impacts of recreation on polar bears

Conservation plans for polar bears (Ursus maritimus) typically cannot prescribe management actions to address their primary threat: sea ice loss associated with climate warming. However, there may be other stressors that compound the negative effects of sea ice loss which can be mitigated. For example, Arctic tourism has increased concurrent with polar bears increasingly using terrestrial habitats, which creates the potential for increased human-bear interactions. Little is known about the types, frequency, or potential impacts of recreation. We conducted a Delphi survey among experts who live and work in polar bear habitats, followed by an internet-based survey to which 47 managers, tour operators, community members, and scientists contributed. Participants identified viewing-based recreation as increasing and affecting the largest proportion of bears within subpopulations that come ashore during the ice-free season. Survey respondents suggested that negative effects of viewing, including displacement and habituation, could be reduced by restricting human use areas and distances between bears and people. Killing of bears in defense was associated more with camping or hunting for other species than other recreations, and may be mitigated with deterrents. Snowmobiling was the most common recreation across the polar bears' range, and reportedly caused some den abandonment and displacement. However, respondents estimated that <10% of polar bears are exposed to most types of recreation and <50% surmised any negative impacts. Nevertheless, mitigating some of the negative impacts identified in this study may become increasingly important as polar bears cope with sea ice loss.

Assessment of global polar bear abundance and vulnerability

AbstractEstimates of abundance and trend are central to assessing population status; yet, are often challenging to obtain or unavailable, suffer from wide confidence intervals and may be collected at irregular intervals. Polar bearsUrsus maritimushave become an iconic species for climate change, yet information on abundance and status for significant parts of their range is unknown. We examine the existing information on subpopulation abundance of polar bears across their range to assess past monitoring. We model the relationship between subpopulation densities and ecological parameters including latitude, continental shelf habitat, prey diversity, sea ice extent and the length of the ice‐free season. Of the 19 subpopulations across the circumpolar Arctic, 14 have estimates (range: 161–2826 bears). Excluding three subpopulations that were regularly monitored, the mean interval between consecutive estimates was 10.9 years (range: 1–36 years), with only six subpopulations having estimates &lt;10 years old. Subpopulation density estimates ranged from 0.57 to 9.30 bears per km2with a mean of 2.36 bears per 1000 km2and a median of 1.71 bears per 1000 km2. Our regression analysis found prey diversity as the only significant correlate with polar bear density. Based on this relationship, we estimate the global population at 23 315 bears (range: 15 972–31 212). An assessment of each subpopulation's vulnerability to climate change based on subpopulation size, amount of continental shelf habitat, prey diversity and changing ice conditions indicates that the Southern Beaufort Sea, Northern Beaufort Sea and Arctic Basin subpopulations are the most vulnerable followed by the Laptev Sea and Viscount Melville Sound subpopulations. With ongoing Arctic warming and the deleterious effects of sea ice loss on polar bears, we recommend that subpopulation assessments be conducted with greater frequency and in subpopulations lacking abundance estimates such that meaningful subpopulation monitoring can proceed.

Indirect effects of sea ice loss on summer‐fall habitat and behaviour for sympatric populations of an Arctic marine predator

AbstractAimClimate change is fundamentally altering habitats, with complex consequences for species across the globe. The Arctic has warmed 2–3 times faster than the global average, and unprecedented sea ice loss can have multiple outcomes for ice‐associated marine predators. Our goal was to assess impacts of sea ice loss on population‐specific habitat and behaviour of a migratory Arctic cetacean.LocationArctic Ocean.MethodsUsing satellite telemetry data collected during summer‐fall from sympatric beluga whale (Delphinapterus leucas) populations (“Chukchi” and “Beaufort” belugas), we applied generalized estimating equations to evaluate shifts in sea ice habitat associations and diving behaviour during two periods: 1993–2002 (“early”) and 2004–2012 (“late”). We used resource selection functions to assess changes in sea ice selection as well as predict trends in habitat selection and “optimal” habitat, based on satellite‐derived sea ice data from 1990 to 2014.ResultsSea ice cover declined substantially between periods, and Chukchi belugas specifically used significantly lower sea ice concentrations during the late than early period. Use of bathymetric features did not change between periods for either population. Population‐specific sea ice selection, predicted habitat and the amount of optimal habitat also generally did not change during 1990–2014. Chukchi belugas tracked during 2007–2012 made significantly more long‐duration and deeper dives than those tracked during 1998–2002.Main conclusionsTaken together, our results suggest bathymetric parameters are consistent predictors of summer‐fall beluga habitat rather than selection for specific sea ice conditions during recent sea ice loss. Beluga whales were able to mediate habitat change despite their sea ice associations. However, trends towards prolonged and deeper diving possibly indicate shifting foraging opportunities associated with ecological changes that occur in concert with sea ice loss. Our results highlight that responses by some Arctic marine wildlife can be indirect and variable among populations, which could be included in predictions for the future.

Habitat degradation affects the summer activity of polar bears.

Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species' distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50-75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.

Major cause of unprecedented Arctic warming in January 2016: Critical role of an Atlantic windstorm

In January 2016, the Arctic experienced an extremely anomalous warming event after an extraordinary increase in air temperature at the end of 2015. During this event, a strong intrusion of warm and moist air and an increase in downward longwave radiation, as well as a loss of sea ice in the Barents and Kara seas, were observed. Observational analyses revealed that the abrupt warming was triggered by the entry of a strong Atlantic windstorm into the Arctic in late December 2015, which brought enormous moist and warm air masses to the Arctic. Although the storm terminated at the eastern coast of Greenland in late December, it was followed by a prolonged blocking period in early 2016 that sustained the extreme Arctic warming. Numerical experiments indicate that the warming effect of sea ice loss and associated upward turbulent heat fluxes are relatively minor in this event. This result suggests the importance of the synoptically driven warm and moist air intrusion into the Arctic as a primary contributing factor of this extreme Arctic warming event.

Suppressed midlatitude summer atmospheric warming by Arctic sea ice loss during 1979–2012

AbstractSince the 1980s, rapid Arctic warming, sea ice decline, and weakening summer circulation have coincided with an increasing number of extreme heat waves and other destructive weather events in the Northern Hemisphere (NH) midlatitudes in summer. Recent papers disagree about whether such high‐impact events are related to Arctic warming and/or ice loss. Here we use atmospheric model ensemble simulations to attribute effects of sea ice loss and other factors on observed summer climate trends during 1979–2012. The ongoing greenhouse gas buildup and resulting sea surface temperature warming outside the Arctic explains nearly all land warming and a significant portion of observed weakening zonal winds in the NH midlatitudes. However, sea ice loss has induced a negative Arctic Oscillation(AO)‐type circulation with significant summer surface and tropospheric cooling trends over large portions of the NH midlatitudes, which reduce the warming and might reduce the probability of regional severe hot summers.

Growth dynamics of saffron cod (Eleginus gracilis) and Arctic cod (Boreogadus saida) in the Northern Bering and Chukchi Seas

Saffron cod (Eleginus gracilis) and Arctic cod (Boreogadus saida) are two circumpolar gadids that serve as critically important species responsible for energy transfer in Arctic food webs of the northern Bering and Chukchi Seas. To understand the potential effects of sea ice loss and warming temperatures on these species׳ basic life history, information such as growth is needed. Yet to date, limited effort has been dedicated to the study of their growth dynamics. Based on a large sample of otoliths collected in the first comprehensive ecosystem integrated survey in the northern Bering and Chukchi Seas, procedures were developed to reliably estimate age from otolith growth zones and were used to study the growth dynamics of saffron and Arctic cod. Annual growth zone assignment was validated using oxygen isotope signatures in otoliths and otolith morphology analyzed and compared between species. Saffron cod attained larger asymptotic sizes (L∞=363mm) and achieved their maximum size at a faster rate (K=0.378) than Arctic cod (L∞=209mm; K=0.312). For both species, regional differences in growth were found (p<0.01). Saffron cod grew to a significantly larger size at age in the northern Bering Sea when compared to the Chukchi Sea, particularly at younger ages. Arctic cod grew to smaller asymptotic size but at faster rates in the more northerly central (L∞=197mm;K=0.324) and southern Chukchi Sea (L∞=221mm;K=0.297) when compared to the northern Bering Sea (L∞=266mm;K=0.171), suggesting a possible cline in growth rates with more northerly latitudes. Comparison of growth to two periods separated by 30 years indicate that both species exhibited a decline in maximum size accompanied by higher instantaneous growth rates in more recent years.

Effects of sea-ice loss

Effects of sea-ice loss

Atmospheric impacts of sea ice decline in CO2 induced global warming

Changes in sea ice cover have important consequences for both Earth’s energy budget and atmospheric dynamics. Sea ice acts as a positive feedback in the climate system, amplifying effects of radiative forcing while also affecting the meridional and interhemispheric temperature gradients that can impact mid- and low latitude atmospheric circulation. In this study, we partition and evaluate the effects of changing sea ice cover on global warming using a set of simulations with active and suppressed sea ice response. Two aspects of CO2-induced sea ice changes are investigated: (1) the effect of changing sea ice cover on global and local temperature changes; and (2) the impact of sea ice loss on atmospheric circulation and extreme weather events. We find that in the absence of sea ice decline, global temperature response decreases by 21–37 %, depending on the sea ice treatment and the CO2 forcing applied. Weakened global warming in the absence of changes in sea ice cover is not only due to a decreased high latitude warming but is also a consequence of a weaker tropical warming. In the northern midlatitudes, sea ice decline affects the magnitude and sign of zonal wind response to global warming in the winter and autumn seasons. Presence or absence of sea ice cover impacts the intensity and frequency of winter extreme precipitation and temperature events (temperature minima, number of heavy precipitation days and number of ice days). For some of the analyzed extreme weather indices, the difference between the responses with and without sea ice decline is eliminated when taking into account the amplifying effect of sea ice loss on hemispheric warming. However, in other cases, we find the influence of higher order factors, exerting weaker but opposing effects than those expected from the global temperature increase.

A tale of two polar bear populations: ice habitat, harvest, and body condition

AbstractOne of the primary mechanisms by which sea ice loss is expected to affect polar bears is via reduced body condition and growth resulting from reduced access to prey. To date, negative effects of sea ice loss have been documented for two of 19 recognized populations. Effects of sea ice loss on other polar bear populations that differ in harvest rate, population density, and/or feeding ecology have been assumed, but empirical support, especially quantitative data on population size, demography, and/or body condition spanning two or more decades, have been lacking. We examined trends in body condition metrics of captured bears and relationships with summertime ice concentration between 1977 and 2010 for the Baffin Bay (BB) and Davis Strait (DS) polar bear populations. Polar bears in these regions occupy areas with annual sea ice that has decreased markedly starting in the 1990s. Despite differences in harvest rate, population density, sea ice concentration, and prey base, polar bears in both populations exhibited positive relationships between body condition and summertime sea ice cover during the recent period of sea ice decline. Furthermore, females and cubs exhibited relationships with sea ice that were not apparent during the earlier period (1977–1990s) when sea ice loss did not occur. We suggest that declining body condition in BB may be a result of recent declines in sea ice habitat. In DS, high population density and/or sea ice loss, may be responsible for the declines in body condition.

The effect of sea ice loss on sea salt aerosol concentrations and the radiative balance in the Arctic

Abstract. Understanding Arctic climate change requires knowledge of both the external and the local drivers of Arctic climate as well as local feedbacks within the system. An Arctic feedback mechanism relating changes in sea ice extent to an alteration of the emission of sea salt aerosol and the consequent change in radiative balance is examined. A set of idealized climate model simulations were performed to quantify the radiative effects of changes in sea salt aerosol emissions induced by prescribed changes in sea ice extent. The model was forced using sea ice concentrations consistent with present day conditions and projections of sea ice extent for 2100. Sea salt aerosol emissions increase in response to a decrease in sea ice, the model results showing an annual average increase in number emission over the polar cap (70–90° N) of 86 × 106 m−2 s−1 (mass emission increase of 23 μg m−2 s−1). This in turn leads to an increase in the natural aerosol optical depth of approximately 23%. In response to changes in aerosol optical depth, the natural component of the aerosol direct forcing over the Arctic polar cap is estimated to be between −0.2 and −0.4 W m−2 for the summer months, which results in a negative feedback on the system. The model predicts that the change in first indirect aerosol effect (cloud albedo effect) is approximately a factor of ten greater than the change in direct aerosol forcing although this result is highly uncertain due to the crude representation of Arctic clouds and aerosol-cloud interactions in the model. This study shows that both the natural aerosol direct and first indirect effects are strongly dependent on the surface albedo, highlighting the strong coupling between sea ice, aerosols, Arctic clouds and their radiative effects.

On the emergence of an Arctic amplification signal in terrestrial Arctic snow extent

The impact of declining sea ice in amplifying surface air temperatures (SAT) over the Arctic Ocean is readily visible, and this “Arctic amplification” will become more pronounced as more sea ice is lost in the coming decades. The effect of sea ice loss on atmospheric temperatures and circulation patterns is of utmost significance as these changes will affect the terrestrial climate. Land‐surface snow is vulnerable to these changes; hence, we search for any link between changes in Arctic sea ice and Northern Hemisphere snow cover. Analyses of observational data sets suggest that the increasing snow cover over Siberia during fall and early winter is correlated with the decreasing September Arctic sea ice over the Pacific sector. We also examine modeled covariance between sea ice and snow using historical and future simulations of the Community Climate System Model (CCSM3). Results indicate the emergence of a Siberian snow signal during the last half of the 21st century most strongly during late winter. Moreover, CCSM3 future simulations show diminishment of snow at a hemispheric scale outside of the Siberian region, which is correlated with the loss of Arctic sea ice. These results indicate that we may be seeing the first, albeit weak, signs of “Arctic amplification” on the terrestrial Arctic snowpack; that only a weak and therefore inconclusive signal would be expected at this time; and that the signal should strengthen over the coming decades.

Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice

1. Observed and predicted declines in Arctic sea ice have raised concerns about marine mammals. In May 2008, the US Fish and Wildlife Service listed polar bears (Ursus maritimus) - one of the most ice-dependent marine mammals - as threatened under the US Endangered Species Act. 2. We evaluated the effects of sea ice conditions on vital rates (survival and breeding probabilities) for polar bears in the southern Beaufort Sea. Although sea ice declines in this and other regions of the polar basin have been among the greatest in the Arctic, to date population-level effects of sea ice loss on polar bears have only been identified in western Hudson Bay, near the southern limit of the species' range. 3. We estimated vital rates using multistate capture-recapture models that classified individuals by sex, age and reproductive category. We used multimodel inference to evaluate a range of statistical models, all of which were structurally based on the polar bear life cycle. We estimated parameters by model averaging, and developed a parametric bootstrap procedure to quantify parameter uncertainty. 4. In the most supported models, polar bear survival declined with an increasing number of days per year that waters over the continental shelf were ice free. In 2001-2003, the ice-free period was relatively short (mean 101 days) and adult female survival was high (0.96-0.99, depending on reproductive state). In 2004 and 2005, the ice-free period was longer (mean 135 days) and adult female survival was low (0.73-0.79, depending on reproductive state). Breeding rates and cub litter survival also declined with increasing duration of the ice-free period. Confidence intervals on vital rate estimates were wide. 5. The effects of sea ice loss on polar bears in the southern Beaufort Sea may apply to polar bear populations in other portions of the polar basin that have similar sea ice dynamics and have experienced similar, or more severe, sea ice declines. Our findings therefore are relevant to the extinction risk facing approximately one-third of the world's polar bears.