The Role of Atmospheric Feedbacks in Abrupt Winter Arctic Sea-Ice Loss in Future Warming Scenarios

2021 ◽  
pp. 1-38
Author(s):  
Camille Hankel ◽  
Eli Tziperman
Keyword(s):  
Sea Ice ◽  
Freezing Point ◽  
Feedback Mechanism ◽  
Arctic Sea Ice ◽  
Heat Fluxes ◽  
Global Climate Models ◽  
Lower Atmosphere ◽  
Arctic Sea ◽  
Arctic Sea Ice Loss

AbstractWinter Arctic sea-ice loss has been simulated with varying degrees of abruptness across Global Climate Models (GCMs) run in the Coupled Model Intercomparison Project 5 (CMIP5) under the high-emissions extended RCP8.5 scenario. Previous studies have proposed various mechanisms to explain modeled abrupt winter sea-ice loss, such as the existence of a wintertime convective cloud feedback or the role of the freezing point as a natural threshold, but none have sought to explain the variability of the abruptness of winter sea-ice loss across GCMs. Here we propose a year-to-year local positive feedback cycle, in which warm, open oceans at the start of winter allow for the moistening and warming of the lower atmosphere, which in turn increases the downwards clear-sky longwave radiation at the surface and suppresses ocean freezing. This leads to delayed and diminished winter sea-ice growth, and allows for increased shortwave absorption due to lowered surface albedo during springtime. Finally, the ocean stores this additional heat throughout the summer and fall seasons, setting up even warmer ocean conditions that lead to further sea-ice reduction. We show that the strength of this feedback, as measured by the partial temperature contributions of the different surface heat fluxes, correlates strongly with the abruptness of winter sea-ice loss across models. Thus, we suggest that this feedback mechanism may explain inter-model spread in the abruptness of winter sea-ice loss. In models where the feedback mechanism is strong, this may indicate the possibility of hysteresis and thus irreversibility of sea-ice loss.

scholarly journals The Role of Extratropical Ocean Warming in the Coupled Climate Response to Arctic Sea Ice Loss

2018 ◽  
Vol 31 (22) ◽  
pp. 9193-9206 ◽  
Author(s):  
Russell Blackport ◽  
Paul J. Kushner
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
General Circulation ◽  
Arctic Sea Ice ◽  
Ocean Warming ◽  
The Arctic ◽  
Climate Response ◽  
Arctic Sea ◽  
Arctic Sea Ice Loss

The role of extratropical ocean warming in the coupled climate response to Arctic sea ice loss is investigated using coupled atmosphere–ocean general circulation model (AOGCM) and uncoupled atmospheric-only (AGCM) experiments. Coupled AOGCM experiments driven by sea ice albedo reduction and greenhouse gas–dominated radiative forcing are used to diagnose the extratropical sea surface temperature (SST) response to sea ice loss. Sea ice loss is then imposed in AGCM experiments both with and without these extratropical SST changes, which are found to extend beyond the regions where sea ice is lost. Sea ice loss in isolation drives warming that is confined to the Arctic lower troposphere and only a weak atmospheric circulation response. When the extratropical SST response caused by sea ice loss is also included in the forcing, the warming extends into the Arctic midtroposphere during winter. This coincides with a stronger atmospheric circulation response, including an equatorward shift in the eddy-driven jet, a deepening of the Aleutian low, and an expansion of the Siberian high. Similar results are found whether the extratropical SST forcing is taken directly from the AOGCM driven by sea ice loss, or whether they are diagnosed using a two-parameter pattern scaling technique where tropical adjustment to sea ice loss is removed. These results suggest that AGCM experiments that are driven by sea ice loss and only local SST increases will underestimate the Arctic midtroposphere warming and atmospheric circulation response to sea ice loss, compared to AOGCM simulations and the real world.

scholarly journals Atmospheric feedback explains disparate climate response to regional Arctic sea-ice loss

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xavier J. Levine ◽  
Ivana Cvijanovic ◽  
Pablo Ortega ◽  
Markus G. Donat ◽  
Etienne Tourigny
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Sea Ice ◽  
Feedback Mechanism ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Climate Response ◽  
Arctic Sea ◽  
Arctic Sea Ice Loss ◽  
Atmospheric Feedback

AbstractArctic sea-ice loss is a consequence of anthropogenic global warming and can itself be a driver of climate change in the Arctic and at lower latitudes, with sea-ice minima likely favoring extreme events over Europe and North America. Yet the role that the sea-ice plays in ongoing climate change remains uncertain, partly due to a limited understanding of whether and how the exact geographical distribution of sea-ice loss impacts climate. Here we demonstrate that the climate response to sea-ice loss can vary widely depending on the pattern of sea-ice change, and show that this is due to the presence of an atmospheric feedback mechanism that amplifies the local and remote signals when broader scale sea-ice loss occurs. Our study thus highlights the need to better constrain the spatial pattern of future sea-ice when assessing its impacts on the climate in the Arctic and beyond.

Sea Ice Loss and Arctic Cyclone Activity from 1979 to 2014

2017 ◽  
Vol 30 (12) ◽  
pp. 4735-4754 ◽  
Author(s):  
Tomoko Koyama ◽  
Julienne Stroeve ◽  
John Cassano ◽  
Alex Crawford
Keyword(s):  
Sea Ice ◽  
Precipitable Water ◽  
Arctic Sea Ice ◽  
Heat Fluxes ◽  
Cyclone Activity ◽  
Subsequent Increase ◽  
Air Temperatures ◽  
Arctic Sea ◽  
Arctic Sea Ice Loss ◽  
Autumn And Winter

Extensive summer sea ice loss has occurred within the Beaufort, Chukchi, East Siberian, and Laptev Seas over the last decade. Associated anomalies in sensible and latent heat fluxes in autumn have increased Arctic atmospheric precipitable water and air temperatures, with the potential to impact autumn and winter cyclone activity. To examine if a connection exists between recent Arctic sea ice loss and cyclone activity, several cyclone metrics from 60° to 90°N are analyzed. Results show that following years with less September sea ice, there is a subsequent increase in moisture availability, regional baroclinicity, and changes in vertical stability that favor cyclogenesis. However, tracking of individual cyclones indicates no coherent increase in cyclone frequency or intensity associated with sea ice loss. Furthermore, no robust northward progression of extreme cyclones is observed.

scholarly journals Probability Assessments of an Ice-Free Arctic: Comparing Statistical and Climate Model Projections

2021 ◽  
Author(s):  
Glenn Rudebusch ◽  
Francis Diebold
Keyword(s):  
Sea Ice ◽  
Carbon Emissions ◽  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
Global Climate Models ◽  
Sea Ice Extent ◽  
Arctic Sea ◽  
Arctic Sea Ice Loss

<p>Based on several decades of satellite data, we provide statistical forecasts of Arctic sea ice extent during the rest of this century. The best fitting statistical model indicates that overall sea ice coverage is declining at an increasing rate. By contrast, average projections from the CMIP5 global climate models foresee a gradual slowing of Arctic sea ice loss even in scenarios with high amounts of carbon emissions. Our long-range statistical projections also deliver <em>probability</em> assessments of the timing of an ice-free Arctic. These results indicate almost a 60 percent chance of an effectively ice-free Arctic Ocean sometime during the 2030s—much earlier than the average projection from the global climate models. Our results are also consistent with projections from bivariate regressions of sea ice extent and carbon emissions. </p>

scholarly journals Elucidating the Role of Anthropogenic Aerosols in Arctic Sea Ice Variations

2017 ◽  
Vol 31 (1) ◽  
pp. 99-114 ◽  
Author(s):  
Yuan Wang ◽  
Jonathan H. Jiang ◽  
Hui Su ◽  
Yong-Sang Choi ◽  
Lei Huang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Arctic Sea Ice ◽  
Arctic Climate ◽  
The Arctic ◽  
Particulate Pollution ◽  
Arctic Sea ◽  
Arctic Climate Change ◽  
Arctic Sea Ice Loss

AbstractObservations show that the Arctic sea ice cover has been shrinking at an unprecedented rate since the 1970s. Even though the accumulation of greenhouse gases in the atmosphere has been closely linked with the loss of Arctic sea ice, the role of atmospheric aerosols in past and future Arctic climate change remains elusive. Using a state-of-the-art fully coupled climate model, the authors assess the equilibrium responses of the Arctic sea ice to the different aerosol emission scenarios and investigate the pathways by which aerosols impose their influence in the Arctic. These sensitivity experiments show that the impacts of aerosol perturbations on the pace of sea ice melt effectively modulate the ocean circulation and atmospheric feedbacks. Because of the contrasting evolutions of particulate pollution in the developed and developing countries since the 1970s, the opposite aerosol forcings from different midlatitude regions are nearly canceled out in the Arctic during the boreal summer, resulting in a muted aerosol effect on the recent sea ice changes. Consequently, the greenhouse forcing alone can largely explain the observed Arctic sea ice loss up to the present. In the next few decades, the projected alleviation of particulate pollution in the Northern Hemisphere can contribute up to 20% of the total Arctic sea ice loss and 0.7°C surface warming over the Arctic. The authors’ model simulations further show that aerosol microphysical effects on the Arctic clouds are the major component in the total aerosol radiative forcing over the Arctic. Compared to the aerosol-induced energy imbalance in lower latitudes outside the Arctic, the local radiative forcing by aerosol variations within the Arctic, due to either local emissions or long-range transports, is more efficient in determining the sea ice changes and Arctic climate change.

scholarly journals The Role of Ocean–Atmosphere Coupling in the Zonal-Mean Atmospheric Response to Arctic Sea Ice Loss

2015 ◽  
Vol 28 (6) ◽  
pp. 2168-2186 ◽  
Author(s):  
Clara Deser ◽  
Robert A. Tomas ◽  
Lantao Sun
Keyword(s):  
Sea Ice ◽  
Hydrological Cycle ◽  
Arctic Sea Ice ◽  
Ocean Dynamics ◽  
Atmospheric Response ◽  
Climate System Model ◽  
Arctic Sea ◽  
Ocean Atmosphere ◽  
Arctic Sea Ice Loss

Abstract The role of ocean–atmosphere coupling in the zonal-mean climate response to projected late twenty-first-century Arctic sea ice loss is investigated using Community Climate System Model version 4 (CCSM4) at 1° spatial resolution. Parallel experiments with different ocean model configurations (full-depth, slab, and no interactive ocean) allow the roles of dynamical and thermodynamic ocean feedbacks to be isolated. In the absence of ocean coupling, the atmospheric response to Arctic sea ice loss is confined to north of 30°N, consisting of a weakening and equatorward shift of the westerlies accompanied by lower tropospheric warming and enhanced precipitation at high latitudes. With ocean feedbacks, the response expands to cover the whole globe and exhibits a high degree of equatorial symmetry: the entire troposphere warms, the global hydrological cycle strengthens, and the intertropical convergence zones shift equatorward. Ocean dynamics are fundamental to producing this equatorially symmetric pattern of response to Arctic sea ice loss. Finally, the absence of a poleward shift of the wintertime Northern Hemisphere westerlies in CCSM4’s response to greenhouse gas radiative forcing is shown to result from the competing effects of Arctic sea ice loss and greenhouse warming on the meridional temperature gradient in middle latitudes.

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