26 March 2025 | 16:00 - 18:00 (MDT) - Part 1
Room: Glen Miller Ballroom - UMC 208
27 March 2025 | 08:30 - 10:00 (MDT) - Part 2
Room: UMC Second Floor 247
Open Session - HYBRID
Organisers: Muyin Wang (University of Washington); Edward Hanna (University of Lincoln); Baek-Min Kim (Pukyong National University)
Zoom link to the Session (26 March) (password-protected)
Zoom link to the Session (27 March) (password-protected)
The password needed to connect to the session will be distributed the day prior to the start of the sessions to all registered conference participants. Further guidelines on how to participate virtually in the ASSW 2025 can be found on the ASSW 2025 website.
Session Description:
Understanding the polar climate system and significantly narrowing uncertainty by constraining climate projections at different temporal and spatial scales are urgent scientific and societal concerns. During the beginning of 21st century, Arctic Amplification (AA) has strengthened, which poses profound implications for global climate dynamics, ecosystem stability, and socio-economic systems. This session calls for studies that seek to advance our understanding of AA patterns and variations, the driving mechanisms, its current and projected impacts, and the development of mitigation and adaptation strategies. Papers are invited from diverse multidisciplinary teams that integrate, atmosphere, oceanography, cryosphere, ecology, and socio-economic studies. Key areas of interest include, but not limited to, feedback processes associated with AA such as snow and ice albedo ocean heat flux effects, permafrost thawing, greenhouse gas emissions; the impact of AA on Arctic biodiversity and human communities; and the development of improved predictive models to forecast future changes. The ultimate goal is to generate comprehensive insights that will inform policy decisions and foster sustainable development in and beyond the Arctic. Contributing papers to this session would identify processes that are playing more critical roles in the changing Arctic environment and gaps of understanding. We especially welcome contributions that demonstrate innovative methodologies, potential for high impact, and collaborative approaches across disciplines and sectors.
Instructions for Speakers: Oral presentations in this session should be at most 10-minutes in length, with an additional 2-3 minutes for questions (unless more detailed instructions are provided by session conveners). See more detailed presenter instructions here.
Oral Presentations - Part 1 on 26 March
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unfold_moreOcean fronts as decadal thermostats modulating Arctic warming and continental warming hiatus — Mi-Kyung Sung
Mi-Kyung Sung 1; Soon-Il An 2; Jongsoo Shin 3; Jae-Heung Park 4; Young-Min Yang 5; Hyo-Jeong Kim 2
1 Korea Institute of Science and Technology; 2 Yonsei University; 3 Woods Hole Oceanographic Institution; 4 Seoul National University; 5 Chonnam UniversityFormat: Oral virtual
Abstract:
Over the past decade, an unexpected cooling trend has been observed in East Asia and North America during winter, contrasting with significant warming in the Arctic regions. Climate model simulations suggest that this pattern of stalled warming in the continental areas, coupled with accelerated warming at higher latitudes, will recur intermittently throughout the course of global warming, influenced by the natural decade-long variations in the climate system. However, understanding the exact factors affecting the pace of warming remains a challenge. Here we show that a pause in warming over continental areas—namely, local warming hiatus—can be accompanied by excessive heat accumulation north of the ocean fronts. This oceanic condition constrains the subseasonal growth of atmospheric planetary waves, thereby increasing the likelihood of cold extremes in downstream continents while simultaneously enhancing poleward heat flux. Our results underscore the importance of closely monitoring changing ocean fronts in response to human-induced warming, which can potentially reshape the inherent decade-long fluctuations within regional climates over the long term.
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unfold_moreMid-latitude cold extremes during the recent period and linkages to Arctic amplification — Judah Cohen
Judah Cohen 1
1 Atmospheric and Environmental Research, Massachusetts Institute of TechnologyFormat: Oral in-person
Abstract:
Therefore, in an effort to understand the relationship between Arctic temperatures and mid-latitude weather, we have extended a recently developed index of accumulated winter season severity index (AWSSI), originally based on temperature and snowfall observations from weather stations in the US only, to the entire Northern Hemisphere using reanalysis output. The expanded index (rAWSSI) is analyzed to reveal relationships between Arctic air temperatures/geopotential heights and the probability of severe winter weather across the midlatitudes. We find a direct and linear relationship between anomalously high Arctic temperatures/geopotential heights and increased severe winter weather, especially in northern and eastern continental regions. Positive temperature trends in specific Arctic regions are associated with increasing trends in severe winter weather in particular midlatitude areas.
Analysis of trends in the frequency and magnitude of cold extremes is mixed across the US and Asia but with a clearer decreasing trend in occurrence across Europe, especially Southern Europe. This divergence between robust Arctic warming and no detectable trends in mid-latitude cold extremes highlights the need for a better understanding of the physical links between Arctic amplification and mid-latitude cold extremes. I will argue that observed resilience in cold extremes can be explained by the behavior of the polar vortex (PV), both stretched PV events and sudden stratospheric warmings.
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unfold_moreUnraveling the Warm Arctic-Cold Continent Pattern: Interplay of Arctic Amplification and Internal Variability in Shaping Mid-latitude Weather — Hoyoung Ku
Hoyoung Ku 1; Baek-Min Kim 1; Muyin Wang 2; James Overland 2; Seong-Joong Kim 3; Gun-Hwan Yang 1
1 Pukyong National University; 2 NOAA/PMEL; 2 NOAA/PMEL; 3 Korea Polar Research InstituteFormat: Oral in-person
Abstract:
The Warm Arctic-Cold Continent (WACC) pattern has been a subject of intense scientific debate, with implications for understanding and predicting mid-latitude weather extremes. This study investigates the primary driver of the WACC pattern, examining the complex interplay between external forcing and internal variability. Using Empirical Orthogonal Function analysis on 84 years (1940-2023) of winter (DJF) temperature over the Northern Hemisphere, we identify three dominant modes of variability: Arctic Amplification (AA), the Arctic Oscillation (AO), and the Barents Oscillation (BO). Our analysis reveals that AA, explaining 27% of the total variance, comprises both externally forced components and substantial internal variability. In contrast, the AO and BO modes (13.8% and 9.7% in variance) exhibit considerable internal variability with negligible long-term trends. During 1990-2014, the interaction between these modes largely explains the observed WACC pattern, with AA driving Arctic warming and negative AO trends contributing to Eurasian cooling. Change point detection analysis reveals distinct cold (1947-1980) and warm (2004-2024) Arctic regimes. During the warm regime, we observe weakened meridional potential vorticity gradients and increased East Siberian blocking frequency during negative AO and BO phases. Idealized model experiments corroborate showing that Arctic warming can amplify potential vorticity gradient reductions under negative AO phases. This study provides novel insights into the mechanisms underlying the WACC pattern, demonstrating that it results from a complex interaction between AA and internal variability modes. Our findings highlight the intricate balance between external forcing and internal variability in shaping Arctic climate change and its mid-latitude impacts.
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unfold_moreHow well does CANARI large ensemble stimulate the stratospheric polar vortex, sudden stratospheric warmings, and stratospheric teleconnection? — Hua Lu
Hua Lu 1; Tony Phillips 1; Thomas Bracegirdle 1; Reinhard Schiemann 2; Ben Harvey 3; Bablu Sinha 4; Gareth Marshall 1
1 British Antarctic Survey; 2 National Centre for Atmospheric Sciences, UK; 3 National Centre for Atmospheric Science; 4 National Oceanography Centre, UKFormat: Oral in-person
Abstract:
The CANARI project, funded by the UK’s Natural Environment Research Council, aims to understand climate change in the Arctic and North Atlantic, its effects on extreme weather, and potential rapid changes. Recently, CANARI produced a Large Ensemble (LE) of climate model simulations using the HadGEM3-GC3.1 model, operating in the Global Coupled configuration 3.1 of the Met Office Unified Model at a resolution of N216ORCA025, with a horizontal resolution of 60 km in the atmosphere and 0.25° in the ocean.
This study uses historical control simulations from CANARI LE to evaluate the stratospheric polar vortex’s mean state and variability during northern winters. It also examines the statistics and influences of sudden stratospheric warmings (SSWs) and the teleconnection between the Quasi-Biennial Oscillation (QBO) and the stratospheric polar vortex, comparing them against ERA5 data. The CANARI LE captures the mid-winter stratospheric polar vortex profile well but has significant biases in the upper and lower stratosphere. It overestimates SSW frequency, though the seasonal distribution aligns with ERA5. The SSW-related Northern Annular Mode (NAM) signal in CANARI LE is weaker and less persistent in the lowermost stratosphere, with a weaker near-surface signal. Possible causes are examined in relation to stratospheric conditions. The LE reproduces the Holton-Tan Effect (HTE), the predominant stratospheric teleconnection. However, the polar vortex response is weaker and located too far equatorward, and it does not feature the observed late winter HTE reversal. These assessments provide a baseline for evaluating climate-forced CANARI LEs as well as other LEs produced by CMIP6 and CMIP7.
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unfold_moreExtreme weather over Eurasia linked to Arctic warming — Seong-Joong Kim
Seong-Joong Kim 1,2; Hyesun Choi 2; Baek-Min Kim 3; Eui-Seok Chung 2; Jeong-Hun Kim 4; Joo-Hong Kim 2; Sang-Yun Jun 2
1 University of Science and Technology; 2 Korea Polar Research Institute; 3 Pukyong National University; 4 Kongju National UniversityFormat: Oral in-person
Abstract:
Eurasia has experienced extreme weather events in recent decades in winter and summer. In winter, cold air outbreaks over Eurasia has been suggested to be linked with rapid Arctic warming, which is more than 4 times faster than the globe. Two pathways from the Arctic warming to winter cold weather in Eurasia have been suggested. The one is through troposphere via the Rossby wave teleconnection. The Rossby wave tends to be activated by the Arctic warming or less sea ice freezing in winter, setting the pressure system more favorable for colder weather over Eurasia. The other is through stratosphere where the polar vortex encircling the Arctic tends to be weaker due to Arctic warming. The extreme weakening of the northern hemisphere polar vortex, i.e., the sudden stratospheric warmings (SSWs), often lead to cold weather over Eurasia. In summer, the warm Arctic and Siberia activate the preexisting Rossby wave, which leads to hot weather in east Asia by setting higher height anomaly over East Asia. Though many studies have suggested the robust relation between Arctic warming and extreme weather over Eurasia, the linkage is not well reproduced in numerical models, limiting extreme weather prediction over Eurasia in various scales linked to the rapid Arctic warming. Better reproduction of the linkage in numerical models for better weather and seasonal prediction will be the utmost important and challenging research topic in the near future.
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unfold_moreRole of ocean and atmospheric process on September sea ice variability in the Arctic Ocean between 2012-2021 — Anirjita Das
Anirjita Das 1; Arnab Mukherjee 1
1 National Centre for Polar and Ocean Research (NCPOR)Format: Oral in-person
Abstract:
It is known that sea ice variability in the Arctic is changing rapidly in the recent decade. This study focuses on the rapid sea ice variability in the Arctic over the past decade, examining year-to-year changes between 2012 and 2021 in Sea Ice Concentration (SIC) and Sea Surface Temperature (SST) across the Arctic Ocean (60°N - 90°N). Using satellite-derived AVHRR observations and the Modular Ocean Model version 5 with Sea Ice Simulator (MOMSIS), the study reveals high SST anomalies in the Barents, Kara, and Laptev Seas, with temperature increases in 2012 (+1.6°C), 2016 (+2.6°C), and 2020 (+3.6°C). Meanwhile, the decadal SIC analysis shows a significant decrease in 2012 (~25-30%), with continued negative anomalies in 2016 (~6-12%) and 2020 (~10-15%).
A mixed-layer heat budget was performed to explore the atmospheric and oceanic processes influencing this variability. Notable Atmospheric Heat Flux (AHF) anomalies were observed in the Kara and Laptev Seas during 2012 (+1.82°C month⁻¹) and 2020 (+1.90°C), with even higher values recorded in the Kara Sea in 2016 (+4.34°C). While oceanic processes, such as vertical entrainment and horizontal advection, generally played a smaller role, they exhibited significant variability, including low horizontal advection in 2020 (-0.69).
Despite being weaker than AHF, oceanic processes contributed to complex interactions, including destructive interference between ocean dynamics and heat fluxes, particularly in the Barents, Kara, Laptev, and East Siberian Seas. These findings highlight the intertwined roles of atmospheric and oceanic factors in driving Arctic climate variability.
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unfold_morePiteraq in Perspective: Long-Term Analysis of Southeast Greenland's Extreme Winds — Tiago Silva
Tiago Silva 1; Kristine Flacké Haualand 2; Caroline Jensen 3; Jacob Clement Yde 4; Jakob Abermann 5; Andreas Trügler 6; Kerstin Rasmussen 7; Johan Hassing 8; Simon de Villiers 9; Wolfgang Schöner 10
1 University of Graz; 2 Department of Civil Engineering and Environmental Sciences, Western Norway University of Applied Sciences, Sogndal, Norway; 3 Danish Meteorological Institute, Copenhagen, Denmark; 4 Department of Civil Engineering and Environmental Sciences, Western Norway University of Applied Sciences, Sogndal, Norway; 5 Department of Geography and Regional Science, University of Graz, Graz, Austria; 6 Department of Geography and Regional Science, University of Graz, Graz, Austria; 7 Department of Geography and Regional Science, University of Graz, Graz, Austria; 8 Danish Meteorological Institute, Copenhagen, Denmark; 9 Department of Civil Engineering and Environmental Sciences, Western Norway University of; 10 Department of Geography and Regional Science, University of Graz, Graz, AustriaFormat: Oral in-person
Abstract:
In Greenlandic, "piteraq" refers to a type of cold, downslope wind that originates from the Greenland ice sheet. Piteraq winds are extremely strong with gusts reaching hurricane force and the potential to cause significant damage to buildings and infrastructure with socio-economic consequences. Tasiilaq, a town located on the southeastern coast of Greenland, is particularly vulnerable to piteraq events. Given the fast atmospheric and oceanic warming along with the diminishing sea ice in the Arctic, it is important to better understand the occurrence and intensity of such extreme events. The Danish Meteorological Institute and the Geological Survey of Denmark and Greenland have been monitoring the weather in and around Tasiilaq with a network of automatic weather stations. Using this network of weather observations in southeast Greenland, we detect piteraq events and describe their duration, intensity, and long-term changes. As a complement to this analysis, we assess the spatio-temporal representation of piteraqs using a polar-adapted regional climate model (RCM) to describe large-scale patterns and the vertical structure associated with piteraqs. Our aim is that the long-term analysis will help advancing the current understanding of piteraq events, improving their detection and enhancing the early warning system to reduce future damage.
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unfold_moreMicrobial community shifts associated with warming in Kongsfjorden — Eva Silva Lopes
Eva Lopes 1
1 Faculty of Sciences of University of Porto, Interdisciplinary Centre of Marine and Environmental ResearchFormat: Oral in-person
Abstract:
Microbial communities (Bacteria and Archaea) play a crucial role in marine ecosystems by driving elemental cycling and supporting food webs. Kongsfjorden has experienced significant warming due to Atlantification, leading to retreating glaciers and reduced sea ice. While the environmental shifts are well documented, their influence on microbial communities remains underexplored. As part of the Kongsfjorden seasonal pelagic monitoring program, we observed pronounced shifts in microbial communities under contrasting environmental conditions. The year 2019 was characterised by a warm spring with limited sea ice, higher temperatures and higher nutrient concentrations compared to 2020, which had a colder, more ice-covered spring. Beta-diversity analysis showed greater within-year variation than between different water depths. Microbial communities in 2019 were more variable and diverse, whereas in 2020 they were more homogenous. Phylum-level differences were significant between the two years, with cyanobacteria more abundant in the warmer 2019 and Bacteroidota and Crenarchaeota dominating in the colder 2020. Cyanobacteria are primary producers, while Bacteroidota degrade organic matter and Crenarchaeota contribute to nitrogen cycling. Network analysis highlighted key microbial interactions, which were more consistent throughout the water column 2019 but diminished at the surface in 2020. Despite fewer interactions in 2020, the community exhibited strong modularity, indicating a resilient structure. This study highlights the role of environmental variability, particularly temperature and ice cover, in shaping microbial diversity and interactions. Our results indicate warmer conditions foster more dynamic communities, while colder conditions promote stability. These findings enhance our understanding of how microbes respond to climate-induced changes in Arctic ecosystems
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unfold_moreInterglacial Transitions and Analogs for Future Climate /Landscape informed by Alaskan Lakes — Julie Brigham-Grette
Julie Brigham-Grette 1; Mary Edwards 2
1 University of Massachusetts-Amherst; 2 University of Alaska FairbanksFormat: Oral in-person
Abstract:
The Arctic is changing so rapidly that by some measures it is outpacing our ability to track changes and project future states. A greater understanding of arctic change is critical for cultural/infrastructure resilience of inhabitants and the role the Arctic plays in the global climate system. Past climate states and variability inform us about the potential rates and limits of ecosystem change, to identify past climate extremes and tangible consequences for the land. Lake sediments are rich archives of past environments, and they record a range of key climate and ecosystem properties that span ice-age cycles (both warmer and colder than present). We will visit sites in Alaska we consider best candidates for long, continuous records to be obtained by deep drilling. Deep drilling explores the unknown; the proposed surveys enhance our ability to develop a proposal to deliver scientifically valuable, sediment sequences and new records of change. This future drilling will provide materials for an unprecedented variety of techniques used to describe climate change, ecosystem interactions, genetic change, and biogeochemical processes. A look at periods of exceptional warmth (e.g., last interglaciation, 125,000 yrs ago) will reveal habitat and landscape changes related to the northward/westward extension of tree/shrub cover, and consequent changes in faunal distributions, all expected in the future with an impact on indigenous resources/land use. We will involve ourselves closely with members of local indigenous communities in co-production and research (including fieldwork participation) and engage with teachers and pupils about project ideas, analyses, results, and practical field activities.
Oral Presentations - Part 2 on 27 March
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unfold_moreStronger Arctic amplification from anthropogenic aerosols than from greenhouse gases — Yu-Chiao Liang
Yu-Chiao Liang 1; You-Ting Wu 2; Michael Previdi 3; Polvani Lorenzo 4; Marck England 5; Michael Sigmond 6
1 National Taiwan University; 2 Columbia University; 3 ldeo; 4 Columbia University; 5 Exeter University; 6 ECCCFormat: Oral virtual
Abstract:
Arctic amplification (AA), the greater Arctic surface warming compared to the global average, has been widely attributed to increasing concentrations of greenhouse gases (GHG). However, less is known about the impacts of other forcings - notably, anthropogenic aerosols (AER) - and how they may compare to the impacts of GHG. Here we analyze sets of climate model simulations, specifically designed to isolate the AER and GHG effects on global climate. Surprisingly, we find stronger AA produced by AER than by GHG during the 1955–1984 period, when the strongest global AER increase. This stronger AER-induced AA is due to a greater sensitivity of Arctic sea ice, and associated changes in ocean-to-atmosphere heat exchange, to AER forcing. Our findings highlight the asymmetric Arctic climate response to GHG and AER forcings, and show that clean air policies which have reduced aerosol emissions may have exacerbated the Arctic warming over the past few decades.
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unfold_moreThe influence of projected Arctic sea-ice loss under 2°C global warming in very large-ensemble climate simulations — Kunhui Ye
Kunhui Ye 1; Tim Woollings 1; Sarah Sparrow 1; Peter Watson 2; James Screen 3
1 University of Oxford; 2 University of Bristol; 3 University of ExeterFormat: Oral virtual
Abstract:
Arctic sea-ice loss and amplified Arctic warming have been one striking signature of climate change with important implications for climate variability in the Arctic and mid-low latitudes. We have performed very large (~2000 members) initial-condition ensemble climate simulations, using two different resolutions, with prescribed boundary conditions (i.e., sea surface temperature and sea-ice concentration) taken from the PAMIP project, to advance understanding of mean climate and extreme weather responses to projected Arctic sea-ice loss under 2°C global warming above preindustrial levels. These simulations better sample internal atmospheric variability and extremes for each model compared to those from the PAMIP, and also allow studying the resolution-dependence of the response to projected Arctic sea-ice using a larger ensemble.
Analysis of these simulations suggests that the mean climate response is mostly consistent with that from the PAMIP multi-model ensemble, including tropospheric warming, reduced midlatitude westerlies and storm track activity, an equatorward shift of the eddy-driven jet and increased mid-to-high latitude blocking. The response of temperature and precipitation extremes largely follows the seasonal-mean response. However, more cold extremes are seen in Asia in response to projected Arctic sea-ice loss. We have also applied a sub-sampling method to isolate dynamic effects of the North Atlantic Oscillation and Siberian High to further understand the response to Arctic sea-ice loss. For example, thermodynamic effects of Arctic warming are more prominent in Europe than in Asia. Overall, our climate simulations highlight that large-ensemble is important for reducing uncertainty in atmospheric circulation and extremes response to projected Arctic sea-ice loss.
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unfold_moreAlfred Wegener Reconnaissance – quantifying Greenland climate and glacier changes on a Centennial Scale — Jakob Abermann
Jakob Abermann 1; Andreas Trügler 1; Florina Schalamon 1; Sebastian Scher 1; Andreas Aschwanden 2; Baptiste Vandecrux 3; Wolfgang Schöner 1
1 Graz University; 5 University of Fairbanks; 6 GEUSFormat: Oral virtual
Abstract:
In this contribution we provide an overview of our activities following up on Alfred Wegener’s pioneering work in the context of his last Greenland expedition 1929-1931. Following a remarkably visionary and broad research agenda, they observed, among other properties, the surface mass balance of an outlet glacier of the Greenland Ice Sheet and measured concurrently meteorological input. The data is archived and has been digitized for the currently running research project (http://www.weg-re.at/). Furthermore, we installed a monitoring infrastructure making use of the data trove stemming from the historical expedition. We aim at capitalizing on the exceptionally high data quality of this unique historical dataset coinciding with the Early Twentieth Century Warm period and the recent observations (2022 - ongoing) to (I) assess differences in large-scale atmospheric weather patterns as drivers for the local mass and energy balance, (II) compare differences in local conditions of air temperature and humidity variability in a confined catchment using high-quality meteorological observations, (III) explore the potential of ML methods in order to constrain (and reduce) uncertainties of reanalysis products, (IV) use our knowledge of high-resolution glacier reconstructions to evaluate a large-scale dynamical model and (IV) use opportunistic field observations such as the development of a proglacial aufeis plain to determine its climatological relevance. We conclude with considerations on determining geometric feedback mechanisms on ice melt based on observations to disentangle Arctic Amplification from local changes.
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unfold_moreThe influence of the lower stratospheric polar vortex on cold air outbreaks under climate warming — Edward Hanna
Edward Hanna 1; Muyin Wang 2; James Overland 3
1 University of Lincoln; 2 University of Washington; 3 NOAA/PMELFormat: Oral virtual
Abstract:
Even now despite midlatitude winter climate warming, major winter cold events, as well as other extreme weather, continue to affect the lives of millions of people in North America, Asia and Europe as well as their economies. The connection between Arctic change and midlatitude weather events is a scientific challenge as events appear local, intermittent, and do not occur every year. This has led to continued controversy in the atmospheric community. Here we move beyond previous efforts by hypothesising that movement of the lower stratospheric polar vortex (SPV) to over the North American or Eurasian continents provides a mechanism for enhancing regional cold air outbreaks, and explains more Linkage events than when only considering Sudden Stratospheric Warmings (SSW). We also review a new non-linear theory of blocking and how this can be used to view Arctic-midlatitude climate linkages. To address these matters, we held a small (19-person) IASC/WCRP CliC (International Arctic Science Committee/World Climate Research Programme Climate & Cryosphere core project) workshop at the University of Lincoln, UK, in September 2023, and included a diverse range of international participants. Workshop discussion and a subsequent paper identified several themes as key priorities for further research, including model improvements, non-linear analyses, and developing a comprehensive framework for stratosphere-troposphere coupling events beyond just SSW, including asymmetric structures of the SPV, the role of large-scale circulation, and more detailed spatio-temporal analysis of the SPV. This talk will review the themes, outcomes and recommendations from the workshop by referring to recent historical cases of Arctic/midlatitude weather connections.
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unfold_moreThe role of precipitation and water vapour in Arctic Amplification — Scott Williamson
Scott Williamson 1
1 Polar Knowledge CanadaFormat: Oral virtual
Abstract:
Arctic Amplification is expressed as the Arctic climate warming at a rate faster than the global or equatorial average. Warming rates increase with latitude, are distributed geographically and seasonally, and appear to be accelerating. The consensus is a warmer Arctic will also be wetter. However, record setting wildfires and low stream flows for the Mackenzie River associated with the ongoing drought in the Sahtu region indicate a regional moisture response to warming. It is unknown how increasing and regionally variable water vapour concentration, precipitation and cloud properties influence warming rates. I explore a range of moisture related phenomena that modify amplified climate change in the Canadian terrestrial Arctic. Examples are drawn from the ongoing drought in the Sahtu region and time series analysis of weather observations, satellite measurements, meteorological records and climate models for the whole of the Canadian terrestrial Arctic. Results will comment on the forcing and feedback role of water vapour in Amplified warming and the implications for wildfire, permafrost degradation, glacier albedo and water security.
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unfold_moreWhat controls the rapid Arctic warming since 1980? — Ash Gilbert
Ash Gilbert 1; Jennifer Kay 1; Edward Blanchard-Wrigglesworth 2; David Schneider 1
1 University of Colorado-Boulder, Cooperative Institute for Research in Environmental Sciences; 2 University of WashingtonFormat: Oral in-person
Abstract:
The Arctic surface temperature (70-90°N) is increasing at 4 times the global rate, an amplification factor that CMIP models struggle to replicate. This enhanced warming rate is connected to Arctic sea ice loss, melting permafrost, and sea level rise from the melting of the Greenland ice sheet. What controls the observed warming trend and interannual variability is not fully understood. Previous work has shown that climate model simulations with CMIP forcing and their winds nudged to observed winds can reproduce both the trend and interannual variability in Arctic temperature and sea ice area. Here, we further attribute the controls on the warming trend and variability. Specifically, we breakdown the individual contribution of the winds, mean state (e.g. the model’s climatology, especially sea ice), and radiative forcings (e.g. changes in greenhouse gases, aerosols, etc.). We find that the winds alone can explain most of the observed interannual variability but not the observed Arctic warming trend (1980-2023). We hypothesize that mean state change sea ice change and associated feedbacks modulate the Arctic warming rate, while forcing contributes the largest amount to the trend. Our work will highlight how this novel methodology can provide new insights on the controls of Arctic warming.
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unfold_moreSeasonality of Arctic Amplification from 1980-2022: The Role of Internal Variability based on Machine Learning — Skylar Gale
Skylar Gale 1
1 Atmospheric and Climate Science, University of WashingtonFormat: Oral in-person
Abstract:
According to observations, Arctic Amplification is as large as 4.2 during 1980-2022. Climate models robustly simulate AA but seldom replicate this observed magnitude. The discrepancy between simulated and observed AA has raised concerns that models may not correctly represent the Arctic’s response to increased greenhouse gas (external) forcings. This simulated response is critical to understanding physical mechanisms and future climate of the Arctic, which can impacts local communities, wildlife, and ecology. Sweeney et al. (2023) reconciled this discrepancy in the annual mean AA by applying an innovative machine learning (ML) algorithm to remove internal variability (inherit chaos of the Earth system) in observed Arctic and global-mean trends, obtaining an observed externally forced AA of 3.0. However, AA has large seasonality and so the simulated and observed AA discrepancy strongly depends on season. To best understand the seasonal impacts from external forcing, we need to breakdown the role of internal variability and compare the simulated AA with observations on a seasonal scale. We use climate model data to train a ML algorithm that uses the seasonal multi-decadal surface air temperature and pressure trend pattern maps to determine the influence of internal variability on seasonal Arctic and global-mean temperature trends. We also use this approach to separate the internally generated and externally forced trends in sea ice extent. The observationally derived forced trends in both temperature and sea ice extent from this study would help better understand climate feedback processes, identify model biases, and constrain simulated forced trends in the Arctic for better prediction purposes.
Poster Presentations (during Poster Exhibit and Session on Wednesday 26 March):
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unfold_moreClimate change and soil microbial communities in Arctic Disko Islands — Natalie Hyde
Natalie Hyde 1; Jana Voriskova 1
1 Institute of Microbiology Czech Academy of SciencesFormat: Poster in-person
Poster number: 33
Abstract:
Climate Change is causing rapid shifts with terrestrial soil temperatures. This is leading to the thawing of permafrost, encroachment of shrubs on biocrusts, and increased wildfires events. Changes with a warming climate in the arctic are expected to increase precipitation in winter seasons, induce more rain on snow events, and increase the number of days spent above freezing temperatures. This causes large shifts to soil microbial community structure and function. Rates of soil nutrient turnover, decomposition and enzymatic activity are expected to increase with warming, causing changes to biogeochemical cycles and carbon cycles in the arctic. I am a masters student working under the Czech institute of microbiology in collaboration with the University of Copenhagen to understand how microbial communities are adapting in response to increased temperatures and snowpack under experimental warming sites on Disko Island in Greenland. The project uses genomics and molecular techniques to study shifts in genetic expression of soil bacteria and fungal communities using metatranscriptomics, metagenomics, and enzymatic assays, to assess questions of how microbial communities in the arctic tundra are changing as a driver of soil warming and increased precipitation events. This work has incentives for agriculutral practices to help researches understand which vegetative species is the least vulnerbale towards future climate induced events, and which pathogenic microbes pose the most risk for crop establishment; while also useful for biotechnology and industry given the ability to use microbial communities as a proxy for understanding genetic adaptations and tolerance to extreme environmental stressors.
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unfold_moreWarming temperatures increase river migration and mobilization of mercury stored in permafrost — M. Isabel Smith
M. Isabel Smith 1; Yutian Ke 2; Emily Geyman 3; Jocelyn Reahl 4; Madison Douglas 5; Emily Seelen 6; John Magyar 7; Kieran Dunne 8; Edda Mutter 9; Woodward Fischer 10; Michael Lamb 11; A. Joshua West 12
1 University of Southern California; 2 California Institute of Technology; 3 California Institute of Technology; 4 University of Colorado Boulder, California Institute of Technology; 5 Califorina Institute of Technology, University of Califorina Berkeley; 6 University of Southern California, University of Alaska Fairbanks; 7 California Institute of Technology; 8 Delft University of Technology, California Institute of Technology; 9 Yukon River Inter-Tribal Watershed Council; 10 California Institute of Technology; 11 California Institute of Technology; 12 University of Southern CaliforinaFormat: Poster in-person
Poster number: 133
Abstract:
Due to long range transport, atmospheric deposition events, and preservation of organic matter, large amounts of mercury are stored in permafrost soils. As the Arctic is experiencing warming rates four times faster than the rest of the planet, permafrost destabilization threatens to release the large amounts of mercury that have accumulated over millennia. While this mercury poses considerable threats to the ecosystems and human health, Arctic mercury stocks remain poorly constrained due to under sampling of Arctic soils. Moreover, the extent to which mercury stored in permafrost will be liberated as permafrost thaws remains unknown.
While there are several processes through which permafrost is lost, this work focuses on river erosion, which can quickly deliver large amounts of mercury-laden sediment along river corridors. Here, we present a new dataset of mercury measurements in riverbank and floodplain sediments and employ a mass balance approach to evaluate the role of river migration on erosional and depositional mercury sediment fluxes in the Yukon River Basin of Alaska. We find that river migration rates play an important role on how much sediment-bound mercury is eroded and reburied. Additionally, we find that thawing permafrost can increase rates of riverbank erosion, which could potentially increase the export of mercury to river water and into the global ocean if the mercury fluxes from the eroded old terrain systematically exceeds the mercury fluxes into the newly-deposited sediments along river corridors.
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unfold_moreDelayed impacts of Arctic sea-ice loss on Eurasian severe cold winters — Yeon-Soo Jang
Yeon-Soo Jang 1; Jong-Seong Kug 2; Sang-Yoon Jun 3; Seok-Woo Son 2; Seung-Ki Min 4; Minho Kwon 1
1 Korea Institute of Ocean Science & Technology; 2 Seoul National University; 3 Korea Polar Research Institute; 4 Pohang University of Science and TechnologyFormat: Poster in-person
Poster number: 166
Abstract:
This study suggests a possible mechanism of how the Arctic sea-ice loss can influence the mid-latitude climate in the Eurasian continent. It is shown that the low sea-ice concentration over the Barents-Kara-Laptev Seas in autumn typically leads to cold Eurasian in winters. It is demonstrated that the Arctic-tomidlatitude connection depends on the state of late autumn atmospheric circulation. When the autumn sea-ice reduction is accompanied by anticyclonic circulation over northern Eurasia, Eurasia becomes anomalously cold in the early winter. However, when cyclonic circulation is dominant, Eurasian cold anomalies appear in the late winter. This seasonally delayed response is further found to be related to the wind-driven sea-ice drift that causes warm anomalies over the Barents-Kara Seas in the following winter. These observational results are confirmed by model simulations, indicating that the recent Eurasian cold winters could be linked to their forced response to the Arctic sea-ice loss.
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unfold_moreSea Ice Model Improvements to Better Constrain Climatic Feedbacks — Geraint Webb
Geraint Webb 1; Nils Hutter 2; Cecilia Bitz 1
1 University of Washington; 2 GEOMAR Helmholtz Centre for Ocean Research KielFormat: Poster in-person
Poster number: 473
Abstract:
Sea ice is composed of floes with a wide range of diameters — these diameters directly impact climatic feedbacks and ice dynamics. The Floe Size Distribution (FSD) quantifies how sea ice floes of varying sizes are distributed across a domain. The sea ice model, CICE, can dynamically evolve the FSD through five key processes: lateral growth, lateral melt, new ice creation, floe welding, and wave fracture. Accurately representing the FSD is important for both the ice-albedo feedback; as such, we seem to improve this representation in models. Currently, CICE overestimates the number of floes in the final (largest diameter) bin by several orders of magnitude (per kilometer squared).
Our work improves CICE’s FSD by modeling an additional process — deformation. The work of Hutter et al. used synthetic aperture radar observations to quantify the change in the FSD due to divergence in the ice velocity field, which generally showed that divergence leads to a decrease in the number of larger floes and an increase in the number of smaller floes. Critically, Hutter’s work culminated in an equation modeling this change, which we implement in the CICE model. Within our model we find a year round decrease in the number of the largest floes, with these larger floes redistributed as many smaller floes. Moreover, the largest change in the FSD occurs in the summer, which significantly decreases the representative floe radius and increases the ice-albedo feedback. Moving forward, we will use this new CICE FSD to improve ice velocity field calculations.
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unfold_moreSpatial and Temporal Analysis of Wildfire Activity in the Selenge River Basin (2000-2023) — Benjamin Lynch
Benjamin Lynch 1; Andrey Petrov 1; Mariia Kuklin 1
1 ARCTICenter University of Northern IowaFormat: Poster in-person
Poster number: 541
Abstract:
Wildfires are a significant natural phenomenon in the boreal forest and steppe of northern Mongolia and Siberia. They present a significant threat to local communities, infrastructure and natural habitats, especially within protected areas. In the last decade the number and intensity of wildfires in the regions, and Selenge River basin has been increasing. This research utilizes MODIS fire data from NASA FIRMS databases to understand spatio-temporal dynamics of fires in the region between 2000 and 2023. Fire occurrences and characteristics are examined to assess seasonal and multi-year changes in fire regimes. Seasonal and annual trends will be studied within the region to find fire activity dynamics over time on different temporal scales. Studying fire activity in this region can provide valuable information for nearby communities and further research on long and short term wildfire trends. Further analysis may be conducted on variables such as FRP, reflectivity and temperature.