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Found 54 results

  1. Potential ocean–atmosphere preconditioning of late autumn Barents-Kara sea ice concentration anomaly Authors: Martin P. King &Javier García-Serrano Published online: 19th February, 2016 Abstract: Many recent studies have revealed the importance of the climatic state in November on the seasonal climate of the subsequent winter. In particular, it has been shown that interannual variability of sea ice concentration (SIC) over the Barents-Kara (BK) seas in November is linked to winter atmospheric circulation anomaly that projects on the North Atlantic Oscillation. Understanding the lead–lag processes involving the different components of the climate system from autumn to winter is therefore important. This note presents dynamical interpretation for the ice-ocean–atmosphere relationships that can affect the BK SIC anomaly in late autumn. It is found that cyclonic (anticyclonic) wind anomaly over the Arctic in October, by Ekman drift, can be responsible for positive (negative) SIC in the BK seas in November. The results also suggest that ocean heat transport via the Barents Sea Opening in September and October can contribute to BK SIC anomaly in November Link to full article (website version): Link to full article (pdf version):
  2. An Update on the Ice Climatology of the Hudson Bay System Authors: Klaus P. Hochheim and David G. Barber Published online: 16th January, 2018 Abstract: The objective of this paper is to examine the thermodynamic and dynamic forcing of sea ice within the Hudson Bay System, including Hudson Bay, Hudson Strait, and Foxe Basin. Changes in fall and spring sea ice extents (SIEs) are examined in relation to seasonal surface air temperatures (SATs) and winds, as are changes in freeze-up dates and breakup dates. The proportional leverage of the fall (lag1) and spring SATs and winds on ice is statistically examined per basin. Results show SATs have increased significantly since the mid-1990s and that increases in the fall are higher than the spring period. Fall SATs are highly related to fall SIEs (R 2 = 0.79–0.82). For every 1 °C increase in SAT, SIE decreases by 14% (% of basin area) within the Hudson Bay System; a 1 °C increase delays freezeup by 0.7 to 0.9 weeks on average. Spring SIEs and breakup dates are shown to be highly correlated with fall (lag1) and spring SATs, and with U and V component winds. Proportionately, spring and fall SATs combined play a dominant role (70–80%) in SIE, and the remaining leverage is attributed to dynamic forcing (winds). The relative leverage of fall (lag1) SATs and surface winds are shown to be significant and vary by basin. The open water season has on average increased by 3.1 (±0.6) weeks in Hudson Bay, 4.9 (±0.8) weeks in Hudson Strait, and 3.5 (±0.9) weeks in Foxe Basin. Link to full article (website version): Link to full article (pdf version):
  3. The Effect of QBO Phase on the Atmospheric Response to Projected Arctic Sea Ice Loss in Early Winter Authors: Zachary Labe, Yannick Peings and Gudrun Magnusdottir Published online: 24th June, 2019 Abstract: Recent modeling studies have shown an important role for stratosphere‐troposphere coupling in the large‐scale atmospheric response to Arctic sea ice loss. Evidence is growing that the Quasi‐biennial Oscillation (QBO) can contribute to or even mitigate teleconnections from surface forcing. Here, the influence of QBO phase on the atmospheric response to projected Arctic sea ice loss is examined using an atmospheric general circulation model with a well‐resolved stratosphere and a QBO prescribed from observations. The role of the QBO is determined by compositing seasons with easterly phase (QBO‐E) separately from seasons with westerly phase (QBO‐W). In response to the sea ice forcing in early winter, the polar vortex during QBO‐E weakens with strong stratosphere‐troposphere wave‐1 coupling and a negative Northern Annular Mode‐type response. At the surface, this results in more severe Siberian cold spells. For QBO‐W, the polar vortex strengthens in response to the sea ice forcing. Plain Language Summary: Rapid loss of Arctic sea ice area and thickness are key indicators of global climate change. Global climate models project further loss of Arctic sea ice through the end of the 21st century. How weather patterns and the jet stream will respond to this sudden loss of sea ice is still poorly understood. Here we use a series of climate model experiments to understand how the atmospheric response to sea ice loss is affected by alternating easterly and westerly winds in the tropical middle atmosphere, known as the Quasi‐biennial Oscillation. We show that the Quasi‐biennial Oscillation has an important role in understanding how weather patterns can respond to a decrease in sea ice. Link to full article: This new paper is still behind the AGU100 paywall - subscibers can access here: Fortunately, Zach Labe has copied most of it to his own website - link here: Before that Zach Labe made a poster presentation on this subject at the 20th Conference on Middle Atmosphere, Phoenix, AZ (Jan 2019): Link to Poster Charts: Link to presentation Summary: Link to 15 minute video: Zach labe also presentented at the AGU Fall meeting in December 2018:
  4. Impact of model resolution on Arctic sea ice and North Atlantic Ocean heat transport Authors: David Docquier et al Published online: 11th June, 2019 Abstract: Arctic sea-ice area and volume have substantially decreased since the beginning of the satellite era. Concurrently, the poleward heat transport from the North Atlantic Ocean into the Arctic has increased, partly contributing to the loss of sea ice. Increasing the horizontal resolution of general circulation models (GCMs) improves their ability to represent the complex interplay of processes at high latitudes. Here, we investigate the impact of model resolution on Arctic sea ice and Atlantic Ocean heat transport (OHT) by using five different state-of-the-art coupled GCMs (12 model configurations in total) that include dynamic representations of the ocean, atmosphere and sea ice. The models participate in the High Resolution Model Intercomparison Project (HighResMIP) of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Model results over the period 1950–2014 are compared to different observational datasets. In the models studied, a finer ocean resolution drives lower Arctic sea-ice area and volume and generally enhances Atlantic OHT. The representation of ocean surface characteristics, such as sea-surface temperature (SST) and velocity, is greatly improved by using a finer ocean resolution. This study highlights a clear anticorrelation at interannual time scales between Arctic sea ice (area and volume) and Atlantic OHT north of 60∘N60∘N in the models studied. However, the strength of this relationship is not systematically impacted by model resolution. The higher the latitude to compute OHT, the stronger the relationship between sea-ice area/volume and OHT. Sea ice in the Barents/Kara and Greenland–Iceland–Norwegian (GIN) Seas is more strongly connected to Atlantic OHT than other Arctic seas. Link to full paper:
  5. The Role of Atlantic Heat Transport in Future Arctic Winter Sea Ice Loss Authors: Marius Årthun, Tor Eldevik and Lars H. Smedsrud Published online: 14th May, 2019 Abstract: During recent decades Arctic sea ice variability and retreat during winter have largely been a result of variable ocean heat transport (OHT). Here we use the Community Earth System Model (CESM) large ensemble simulation to disentangle internally and externally forced winter Arctic sea ice variability, and to assess to what extent future winter sea ice variability and trends are driven by Atlantic heat transport. We find that OHT into the Barents Sea has been, and is at present, a major source of internal Arctic winter sea ice variability and predictability. In a warming world (RCP8.5), OHT remains a good predictor of winter sea ice variability, although the relation weakens as the sea ice retreats beyond the Barents Sea. Warm Atlantic water gradually spreads downstream from the Barents Sea and farther into the Arctic Ocean, leading to a reduced sea ice cover and substantial changes in sea ice thickness. The future long-term increase in Atlantic heat transport is carried by warmer water as the current itself is found to weaken. The externally forced weakening of the Atlantic inflow to the Barents Sea is in contrast to a strengthening of the Nordic Seas circulation, and is thus not directly related to a slowdown of the Atlantic meridional overturning circulation (AMOC). The weakened Barents Sea inflow rather results from regional atmospheric circulation trends acting to change the relative strength of Atlantic water pathways into the Arctic. Internal OHT variability is associated with both upstream ocean circulation changes, including AMOC, and large-scale atmospheric circulation anomalies reminiscent of the Arctic Oscillation. Link to full paper:
  6. Benchmark seasonal prediction skill estimates based on regional indices (Arctic Ice Extent) Authors: John E. Walsh, J. Scott Stewart and Florence Fetterer Published in "The Cryosphere": 3rd April, 2019 Abstract: Basic statistical metrics such as autocorrelations and across-region lag correlations of sea ice variations provide benchmarks for the assessments of forecast skill achieved by other methods such as more sophisticated statistical formulations, numerical models, and heuristic approaches. In this study we use observational data to evaluate the contribution of the trend to the skill of persistence-based statistical forecasts of monthly and seasonal ice extent on the pan-Arctic and regional scales. We focus on the Beaufort Sea for which the Barnett Severity Index provides a metric of historical variations in ice conditions over the summer shipping season. The variance about the trend line differs little among various methods of detrending (piecewise linear, quadratic, cubic, exponential). Application of the piecewise linear trend calculation indicates an acceleration of the winter and summer trends during the 1990s. Persistence-based statistical forecasts of the Barnett Severity Index as well as September pan-Arctic ice extent show significant statistical skill out to several seasons when the data include the trend. However, this apparent skill largely vanishes when the data are detrended. In only a few regions does September ice extent correlate significantly with antecedent ice anomalies in the same region more than 2 months earlier. The springtime “predictability barrier” in regional forecasts based on persistence of ice extent anomalies is not reduced by the inclusion of several decades of pre-satellite data. No region shows significant correlation with the detrended September pan-Arctic ice extent at lead times greater than a month or two; the concurrent correlations are strongest with the East Siberian Sea. The Beaufort Sea's ice extent as far back as July explains about 20 % of the variance of the Barnett Severity Index, which is primarily a September metric. The Chukchi Sea is the only other region showing a significant association with the Barnett Severity Index, although only at a lead time of a month or two. Link to full paper:
  7. Arctic Sea Ice Volume Variability over 1901–2010: A Model-Based Reconstruction Authors: Axel J. Schweiger, Kevin R. Wood and Jinlun Zhang Published: 3rd July, 2019 Abstract: PIOMAS-20C, an Arctic sea ice reconstruction for 1901–2010, is produced by forcing the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) with ERA-20C atmospheric data. ERA-20C performance over Arctic sea ice is assessed by comparisons with measurements and data from other reanalyses. ERA-20C performs similarly with respect to the annual cycle of downwelling radiation, air temperature, and wind speed compared to reanalyses with more extensive data assimilation such as ERA-Interim and MERRA. PIOMAS-20C sea ice thickness and volume are then compared with in situ and aircraft remote sensing observations for the period of ~1950–2010. Error statistics are similar to those for PIOMAS. We compare the magnitude and patterns of sea ice variability between the first half of the twentieth century (1901–40) and the more recent period (1980–2010), both marked by sea ice decline in the Arctic. The first period contains the so-called early-twentieth-century warming (ETCW; ~1920–40) during which the Atlantic sector saw a significant decline in sea ice volume, but the Pacific sector did not. The sea ice decline over the 1979–2010 period is pan-Arctic and 6 times larger than the net decline during the 1901–40 period. Sea ice volume trends reconstructed solely from surface temperature anomalies are smaller than PIOMAS-20C, suggesting that mechanisms other than warming, such as changes in ice motion and deformation, played a significant role in determining sea ice volume trends during both periods. Link to full paper: Supplemental Material:
  8. The Interconnected Global Climate System—A Review of Tropical–Polar Teleconnections Authors: Xiaojun Yuan, Michael R. Kaplan, and Mark A. Cane Published: 29th June, 2018 Abstract: This paper summarizes advances in research on tropical–polar teleconnections, made roughly over the last decade. Elucidating El Niño–Southern Oscillation (ENSO) impacts on high latitudes has remained an important focus along different lines of inquiry. Tropical to polar connections have also been discovered at the intraseasonal time scale, associated with Madden–Julian oscillations (MJOs). On the time scale of decades, changes in MJO phases can result in temperature and sea ice changes in the polar regions of both hemispheres. Moreover, the long-term changes in SST of the western tropical Pacific, tropical Atlantic, and North Atlantic Ocean have been linked to the rapid winter warming around the Antarctic Peninsula, while SST changes in the central tropical Pacific have been linked to the warming in West Antarctica. Rossby wave trains emanating from the tropics remain the key mechanism for tropical and polar teleconnections from intraseasonal to decadal time scales. ENSO-related tropical SST anomalies affect higher-latitude annular modes by modulating mean zonal winds in both the subtropics and midlatitudes. Recent studies have also revealed the details of the interactions between the Rossby wave and atmospheric circulations in high latitudes. We also review some of the hypothesized connections between the tropics and poles in the past, including times when the climate was fundamentally different from present day especially given a larger-than-present-day global cryosphere. In addition to atmospheric Rossby waves forced from the tropics, large polar temperature changes and amplification, in part associated with variability in orbital configuration and solar irradiance, affected the low–high-latitude connections. Link to full paper:
  9. Minimal influence of reduced Arctic sea ice on coincident cold winters in mid-latitudes Authors: Russell Blackport, James A. Screen, Karin van der Wiel and Richard Bintanja Published: 12th August, 2019 Abstract: Observations show that reduced regional sea-ice cover is coincident with cold mid-latitude winters on interannual timescales. However, it remains unclear whether these observed links are causal, and model experiments suggest that they might not be. Here we apply two independent approaches to infer causality from observations and climate models and to reconcile these sources of data. Models capture the observed correlations between reduced sea ice and cold mid-latitude winters, but only when reduced sea ice coincides with anomalous heat transfer from the atmosphere to the ocean, implying that the atmosphere is driving the loss. Causal inference from the physics-based approach is corroborated by a lead–lag analysis, showing that circulation-driven temperature anomalies precede, but do not follow, reduced sea ice. Furthermore, no mid-latitude cooling is found in modelling experiments with imposed future sea-ice loss. Our results show robust support for anomalous atmospheric circulation simultaneously driving cold mid-latitude winters and mild Arctic conditions, and reduced sea ice having a minimal influence on severe mid-latitude winters. Link to full paper: Unfortunately this fascinating very recent paper is still behind the "Nature Climate Change" paywall. I'm not a subscriber but if anyone is, then here's the link: If/when the paper becomes freely available, the link will appear here. In the meantime, if anyone does have a link (with permissions), please PM me or "reply to topic" below. Then I can add the link sooner and I can give you credit for finding the paper. I did find several articles about this paper which provide a little more detail: A word of caution: I prefer to read the full paper before placing a link into the portal. Some of these "climate change" related papers have exaggerated views (from extremists at either end of the climate change debate) and I prefer to take a balanced view and include papers which come from known reliable authors. As this source is from the University of Exeter (just 10 miles from where I live) and also two Netherlands met institutes I have no reason to believe that the research in this paper is not legitimate even though the findings differ quite considerably from other recent research. David
  10. Investigating the local-scale influence of sea ice on Greenland surface melt Authors: Julienne C. Stroeve, John R. Mioduszewski, Asa Rennermalm, Linette N. Boisvert, Marco Tedesco and David Robinson Published: 23rd October, 2017 Abstract: Rapid decline in Arctic sea ice cover in the 21st century may have wide-reaching effects on the Arctic climate system, including the Greenland ice sheet mass balance. Here, we investigate whether local changes in sea ice around the Greenland ice sheet have had an impact on Greenland surface melt. Specifically, we investigate the relationship between sea ice concentration, the timing of melt onset and open-water fraction surrounding Greenland with ice sheet surface melt using a combination of remote sensing observations, and outputs from a reanalysis model and a regional climate model for the period of 1979–2015. Statistical analysis points to covariability between Greenland ice sheet surface melt and sea ice within Baffin Bay and Davis Strait. While some of this covariance can be explained by simultaneous influence of atmospheric circulation anomalies on both the sea ice cover and Greenland melt, within Baffin Bay we find a modest correlation between detrended melt onset over sea ice and the adjacent ice sheet melt onset. This correlation appears to be related to increased transfer of sensible and latent heat fluxes from the ocean to the atmosphere in early sea ice melt years, increasing temperatures and humidity over the ice sheet that in turn initiate ice sheet melt. Link to full paper:
  11. Sea ice circulation around the Beaufort Gyre: The changing role of wind forcing and the sea ice state Authors: Alek A. Petty, Jennifer K. Hutchings, Jacqueline A. Richter‐Menge and Mark A. Tschudi First Published: 20th April, 2016 Abstract: Sea ice drift estimates from feature tracking of satellite passive microwave data are used to investigate seasonal trends and variability in the ice circulation around the Beaufort Gyre, over the multidecadal period 1980–2013. Our results suggest an amplified response of the Beaufort Gyre ice circulation to wind forcing, especially during the late 2000s. We find increasing anticyclonic ice drift across all seasons, with the strongest trend in autumn, associated with increased ice export out of the southern Beaufort Sea (into the Chukchi Sea). A flux gate analysis highlights consistency across a suite of drift products. Despite these seasonal anticyclonic ice drift trends, a significant anticyclonic wind trend occurs in summer only, driven, in‐part, by anomalously anticyclonic winds in 2007. Across all seasons, the ice drift curl is more anticyclonic than predicted from a linear relationship to the wind curl in the 2000s, compared to the 1980s/1990s. The strength of this anticyclonic ice drift curl amplification is strongest in autumn and appears to have increased since the 1980s (up to 2010). In spring and summer, the ice drift curl amplification occurs mainly between 2007 and 2010. These results suggest nonlinear ice interaction feedbacks (e.g., a weaker, more mobile sea ice pack), enhanced atmospheric drag, and/or an increased role of the ocean. The results also show a weakening of the anticyclonic wind and ice circulation since 2010. Link to full paper: Link to pdf version:
  12. In a Spin: New Insights into the Beaufort Gyre Publication: EOS - Earth, Space and Science News Authors: Andrey Proshutinsky and Richard Krishfieldon First Published: 8th April, 2019 Abstract: None - this from "Researchgate": A new special collection in JGR: Oceans presents results from studies of the Beaufort Gyre, an oceanic circulation system in the Arctic that has far-reaching influence on the global climate. My recommendation: This article provides an excellent overview for learners of the Beaufort Gyre and how important its influence is it is not only in the Arctic region but also in terms of the northern hemisphere fand global circulation currents and patterns. This superb chart is in the article: I will add further important papers on the Beaufort Gyre over the next few weeks. Link to full paper:
  13. A comparison of Arctic sea ice in July - 2019 vs 2012 - YouTube Presentation Presented By: Seemorerocks 97 Presentation Date: 23rd July, 2019 Abstract: None My Summary: Seemorerocks is a climate change protagonist and writes regular blogs under this name. This was his analysis of the very low summer 2019 Arctic sea ice extent with a "possibilty" of the 2012 record all time low being beaten. He does a comparison between 2012 and 2019 drawing on data from Zach Labe. He used the following sources: NASA "World View" satellite imagery (source:,-3485696,6690640.334728033,3485696&p=arctic&t=2019-04-12-T00%3A00%3A00Z&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines ) US Navy NSIRCC site (source: The 2012 "Great Arctic Cyclone" (source: I have added several other papers and presentations to the portal on the August 2012 cyclone and on the 2012 Arctic profile more generally and more will follow shortly. For the sake of balance, most of the authors conclude that the cyclone was only one of a number of factors at play that produced the record minimum extent in 2012. Link to YouTube presentation (16 minutes):
  14. Impacts of the Record Arctic Sea Ice Minimum of 2012 - Presentation 93rd AMS Annual Conference: from 5th to 10th January, 2013 at Austin Convention centre Session 1 on 8th January, 2013: "Global Weather Impacts in 2012" Presenters: Mark C. Serreze Presentation Date (time): 8th January, 2013 (0915) Presentation Summary: On 16 September, 2012, Arctic sea ice extent dropped to the lowest level recorded over the satellite era, which at 3.49 million square km was 18% lower than the previous record low extent set in September 2007. The summer of 2007 featured unusually high sea level pressure centered north of the Beaufort Sea and Greenland, paired with unusually low pressure along northern Eurasia, bringing in warm southerly winds along the shores of the East Siberian and Chukchi seas, favoring strong ice melt in these sectors and pushing the ice away from the coast, leaving open water. The pressure pattern also favored the transport of ice out of the Arctic Ocean and into the North Atlantic through Fram Strait. By sharp contrast, apart from an unusually strong low pressure system in the first week of August centered over the northern Beaufort Sea, weather patterns during the summer of 2012 were unremarkable. While evaluations are ongoing as this abstract is written, it appears that in response to a warming Arctic over the past several decades, the spring ice cover is now so thin that large parts of the sea ice cover are now simply unable to survive the summer melt season. Through the summer of 2012, the Arctic Ocean absorbed a great deal of solar energy in dark open water areas. The release of this stored heat to the atmosphere during the autumn and winter, manifested as strong positive anomalies in surface and lower tropospheric temperatures, serves as an exclamation point on the ongoing process of Arctic amplification – the observed outsized rise in air temperatures over the Arctic compared to the globe as a whole. Whether this outsized warming will influence autumn and winter weather patterns beyond the Arctic region, as has been argued to have been the case in other recent years with low end-of-summer sea ice extent, remains to be seen. What is clear is that the events of 2012 have further raised awareness of the economic and strategic importance of the Arctic through its growing accessibility to marine shipping and extraction of natural resources. Link to full video presentation (15 minutes): Link to the full conference agenda:
  15. The great Arctic cyclone of August 2012 Authors: Ian Simmonds and Irina Rudeva First Published: 15th December, 2012 Abstract: On 2 August 2012 a dramatic storm formed over Siberia, moved into the Arctic, and died in the Canadian Arctic Archipelago on 14 August. During its lifetime its central pressure dropped to 966 hPa, leading it to be dubbed ‘The Great Arctic Cyclone of August 2012’. This cyclone occurred during a period when the sea ice extent was on the way to reaching a new satellite‐era low, and its intense behavior was related to baroclinicity and a tropopause polar vortex. The pressure of the storm was the lowest of all Arctic August storms over our record starting in 1979, and the system was also the most extreme when a combination of key cyclone properties was considered. Even though, climatologically, summer is a ‘quiet’ time in the Arctic, when compared withall Arctic storms across the period it came in as the 13th most extreme storm, warranting the attribution of ‘Great’. Link to full paper:
  16. Extreme Arctic cyclone in August 2016 Authors: Akio Yamagami, Mio Matsueda and Hiroshi L. Tanaka First Published: 12th July, 2017 Abstract: An extremely strong Arctic cyclone (AC) developed in August 2016. The AC exhibited a minimum sea level pressure (SLP) of 967.2 hPa and covered the entire Pacific sector of the Arctic Ocean on 16 August. At this time, the AC was comparable to the strong AC observed in August 2012, in terms of horizontal extent, position, and intensity as measured by SLP. Two processes contributed to the explosive development of the AC: growth due to baroclinic instability, similar to extratropical cyclones, during the early phase of the development stage, and later nonlinear development via the merging of upper warm cores. The AC was maintained for more than 1 month through multiple mergings with cyclones both generated in the Arctic and migrating northward from lower latitudes, as a result of the high cyclone activity in summer 2016. Link to full paper: Alternative pdf version:
  17. On the 2012 record low Arctic sea ice cover: Combined impact of preconditioning and an August storm Authors: Claire L. Parkinson and Josefino C. Comiso First Published: 14th March, 2013 Abstract: A new record low Arctic sea ice extent for the satellite era, 3.4 × 106 km2, was reached on 13 September 2012; and a new record low sea ice area, 3.0 × 106 km2, was reached on the same date. Preconditioning through decades of overall ice reductions made the ice pack more vulnerable to a strong storm that entered the central Arctic in early August 2012. The storm caused the separation of an expanse of 0.4 × 106 km2 of ice that melted in total, while its removal left the main pack more exposed to wind and waves, facilitating the main pack's further decay. Future summer storms could lead to a further acceleration of the decline in the Arctic sea ice cover and should be carefully monitored. Link to full paper: Alternative pdf version:
  18. Seasonal sea ice forecast skills and predictability of the KMA's GloSea5 Authors: Byoung Woong An, Sang Min Lee, Pil-Hun Chang, KiRyong Kang, and Yoon Jae Kim First Published: 7th December, 2018 Abstract: Ensemble sea ice forecasts of the Arctic Ocean conducted with the Korea Meteorological Administration's coupled global seasonal forecast system (GloSea5) is verified. To investigate the temporal and spatial characteristics of the seasonal projection of Arctic sea ice extent and thickness, a set of ensemble potential predictability is assessed. It shows significance for all lead months except anomalous around East Siberian Sea, Chukchi Sea and Beaufort Sea during summer months. However, during the rapidly thawing and freezing season, initial states lose its predictability and increase uncertainties in the prediction. The probability skill metrics show the summer sea ice prediction which strongly depends on the sea ice thickness interacting with the accuracy of the snow depth. We found the forecast skill is determined primarily by the timing of sea ice drift (i.e., Beaufort Gyre and Transpolar drift) and sea ice formation by freshwater flux in the East Siberian Sea. Therefore, capturing the sea ice thickness state effectively is the key process for skillful estimation of Arctic sea ice. In spite of the uncertainties in atmospheric conditions, this system provides skillful Arctic seasonal sea ice extent predictions up to six months. Link to full paper:
  19. The urgency of Arctic change Authors: James Overland, Edward Dunlea, Jason E.Box, Robert Corell, Martin Forsius, Vladimir Kattsov, Morten Skovg ård Olsen, Janet Pawlak, Lars-OttoReiersen and MuyinWang Published: November 27th, 2018 Abstract: This article provides a synthesis of the latest observational trends and projections for the future of the Arctic. First, the Arctic is already changing rapidly as a result of climate change. Contemporary warm Arctic temperatures and large sea ice deficits (75% volume loss) demonstrate climate states outside of previous experience. Modeled changes of the Arctic cryosphere demonstrate that even limiting global temperature increases to near 2 °C will leave the Arctic a much different environment by mid-century with less snow and sea ice, melted permafrost, altered ecosystems, and a projected annual mean Arctic temperature increase of +4 °C. Second, even under ambitious emission reduction scenarios, high-latitude land ice melt, including Greenland, are foreseen to continue due to internal lags, leading to accelerating global sea level rise throughout the century. Third, future Arctic changes may in turn impact lower latitudes through tundra greenhouse gas release and shifts in ocean and atmospheric circulation. Arctic-specific radiative and heat storage feedbacks may become an obstacle to achieving a stabilized global climate. In light of these trends, the precautionary principle calls for early adaptation and mitigation actions. Link to full paper (on the "ScienceDirect" website): Link to pdf early manuscript version of the paper:
  20. How Global Warming and Arctic Ice Melt Intensify Hurricanes - YouTube Presentation Presented By: Dr Jennifer Francis (Research Professor at Rutgers University's Institute of Marine and Coastal Sciences since 1994) Interviewed By: Greg Wilpert Broadcast Team: The Real News Network Presentation Date: 21st September, 2018 Link to YouTube presentation (13 minutes): You can click on the chart above or use this link:
  21. Changing state of Arctic sea ice across all seasons Authors: Julienne Stroeve and Dirk Notz Published: Sept 2018 Abstract: The decline in the floating sea ice cover in the Arctic is one of the most striking manifestations of climate change. In this review, we examine this ongoing loss of Arctic sea ice across all seasons. Our analysis is based on satellite retrievals, atmospheric reanalysis, climate-model simulations and a literature review. We find that relative to the 1981–2010 reference period, recent anomalies in spring and winter sea ice coverage have been more significant than any observed drop in summer sea ice extent (SIE) throughout the satellite period. For example, the SIE in May and November 2016 was almost four standard deviations below the reference SIE in these months. Decadal ice loss during winter months has accelerated from −2.4 %/decade from 1979 to 1999 to −3.4%/decade from 2000 onwards. We also examine regional ice loss and find that for any given region, the seasonal ice loss is larger the closer that region is to the seasonal outer edge of the ice cover. Finally, across all months, we identify a robust linear relationship between pan-Arctic SIE and total anthropogenic CO2 emissions. The annual cycle of Arctic sea ice loss per ton of CO2 emissions ranges from slightly above 1 m2 throughout winter to more than 3 m2 throughout summer. Based on a linear extrapolation of these trends, we find the Arctic Ocean will become sea-ice free throughout August and September for an additional 800 ± 300 Gt of CO2 emissions, while it becomes ice free from July to October for an additional 1400 ± 300 Gt of CO2 emissions. Link to full paper:
  22. Seasonal and Regional Manifestation of Arctic Sea Ice Loss Authors: Ingrid H. Onarheim, Tor Eldevik, Lars H. Smedsrud, Julienne C. Stroeve Published: May2018 Abstract: The Arctic Ocean is currently on a fast track toward seasonally ice-free conditions. Although most attention has been on the accelerating summer sea ice decline, large changes are also occurring in winter. This study assesses past, present, and possible future change in regional Northern Hemisphere sea ice extent throughout the year by examining sea ice concentration based on observations back to 1950, including the satellite record since 1979. At present, summer sea ice variability and change dominate in the perennial ice-covered Beaufort, Chukchi, East Siberian, Laptev, and Kara Seas, with the East Siberian Sea explaining the largest fraction of September ice loss (22%). Winter variability and change occur in the seasonally ice-covered seas farther south: the Barents Sea, Sea of Okhotsk, Greenland Sea, and Baffin Bay, with the Barents Sea carrying the largest fraction of loss in March (27%). The distinct regions of summer and winter sea ice variability and loss have generally been consistent since 1950, but appear at present to be in transformation as a result of the rapid ice loss in all seasons. As regions become seasonally ice free, future ice loss will be dominated by winter. The Kara Sea appears as the first currently perennial ice-covered sea to become ice free in September. Remaining on currently observed trends, the Arctic shelf seas are estimated to become seasonally ice free in the 2020s, and the seasonally ice-covered seas farther south to become ice free year-round from the 2050s. Link to full paper:
  23. The influence of Arctic amplification on mid-latitude summer circulation Authors: D. Coumou, G. Di Capua, S. Vavrus, L. Wang & S. Wang Published: 20th August 2018 Abstract: Accelerated warming in the Arctic, as compared to the rest of the globe, might have profound impacts on mid-latitude weather. Most studies analyzing Arctic links to mid-latitude weather focused on winter, yet recent summers have seen strong reductions in sea-ice extent and snow cover, a weakened equator-to-pole thermal gradient and associated weakening of the mid-latitude circulation. We review the scientific evidence behind three leading hypotheses on the influence of Arctic changes on mid-latitude summer weather: Weakened storm tracks, shifted jet streams, and amplified quasi-stationary waves. We show that interactions between Arctic teleconnections and other remote and regional feedback processes could lead to more persistent hot-dry extremes in the mid-latitudes. The exact nature of these non-linear interactions is not well quantified but they provide potential high-impact risks for society. Link to full paper:
  24. Projected SSTs over 21st century: Changes in mean, variability & extremes for large marine ecosystem regions of Northern Oceans Authors: Michael A. Alexander (NOAA), James D. Scott, Kevin D. Friedland, Katherine E. Mills, Janet A. Nye, Andrew J. Pershing and Andrew C. Thomas Published: 26th January, 2018 Abstract: Global climate models were used to assess changes in the mean, variability and extreme sea surface temperatures (SSTs) in northern oceans with a focus on large marine ecosystems (LMEs) adjacent to North America, Europe, and the Arctic Ocean. Results were obtained from 26 models in the Community Model Intercomparison Project Phase 5 (CMIP5) archive and 30 simulations from the National Center for Atmospheric Research Large Ensemble Community Project (CESM-LENS). All of the simulations used the observed greenhouse gas concentrations for 1976–2005 and the RCP8.5 “business as usual” scenario for greenhouse gases through the remainder of the 21st century. In general, differences between models are substantially larger than among the simulations in the CESM-LENS, indicating that the SST changes are more strongly affected by model formulation than internal climate variability. The annual SST trends over 1976–2099 in the 18 LMEs examined here are all positive ranging from 0.05 to 0.5°C decade–1. SST changes by the end of the 21st century are primarily due to a positive shift in the mean with only modest changes in the variability in most LMEs, resulting in a substantial increase in warm extremes and decrease in cold extremes. The shift in the mean is so large that in many regions SSTs during 2070–2099 will always be warmer than the warmest year during 1976–2005. The SST trends are generally stronger in summer than in winter, as greenhouse gas heating is integrated over a much shallower climatological mixed layer depth in summer than in winter, which amplifies the seasonal cycle of SST over the 21stcentury. In the Arctic, the mean SST and its variability increases substantially during summer, when it is ice free, but not during winter when a thin layer of ice reforms and SSTs remain near the freezing point. Link to full paper: Link to a presentation of this paper (slides only): extra slides.pdf
  25. A stratospheric pathway linking a colder Siberia to Barents-Kara Sea sea ice loss Authors: Pengfei Zhang, Yutian Wu, Isla R. Simpson, Karen L. Smith, Xiangdong Zhang, Bithi De and Patrick Callaghan Published: July 2018 Abstract: Previous studies have extensively investigated the impact of Arctic sea ice anomalies on the midlatitude circulation and associated surface climate in winter. However, there is an ongoing scientific debate regarding whether and how sea ice retreat results in the observed cold anomaly over the adjacent continents. We present a robust “cold Siberia” pattern in the winter following sea ice loss over the Barents-Kara seas in late autumn in an advanced atmospheric general circulation model, with a well-resolved stratosphere. Additional targeted experiments reveal that the stratospheric response to sea ice forcing is crucial in the development of cold conditions over Siberia, indicating the dominant role of the stratospheric pathway compared with the direct response within the troposphere. In particular, the downward influence of the stratospheric circulation anomaly significantly intensifies the ridge near the Ural Mountains and the trough over East Asia. The persistently intensified ridge and trough favor more frequent cold air outbreaks and colder winters over Siberia. This finding has important implications for improving seasonal climate prediction of mid-latitude cold events. The results also suggest that the model performance in representing the stratosphere-troposphere coupling could be an important source of the discrepancy between recent studies. Link to full paper:
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