Pub Date : 2025-12-01Epub Date: 2025-11-10DOI: 10.1016/j.polar.2025.101301
Toshisuke Kawasaki
This is a report of the mineral inclusions in magnetite megacryst within pegmatite, cutting the granulite-facies medium-grained pyroxene gneisses from West Ongul Island, Lützow-Holm Complex, East Antarctica. Inclusions involve a monophase or multiphase assemblage that consists of various combinations of anatase, andalusite, biotite, corundum, diaspore, högbomite, hematite, ilmenite, kaolinite, monazite, muscovite, plagioclase, pseudorutile, quartz, rutile, sillimanite, spinel and zircon. These occur as independent minerals, lamellae, seams, sticks on lamella and seam, aggregates along the magnetite–ilmenite boundary, altered minerals and edge minerals of megacryst.
West Ongul magnetite crystallised in pegmatite at around 4 kbar and 680 ℃ under hydrous ( bar) and oxidising ( bar) conditions. Cooling – path of pegmatite after magnetite crystallisation is estimated to cut through the wet solidus of muscovite granite at around 3 kbar and 650 ℃. Subsequently, the – condition changed to the rutile anatase boundary at around 2 kbar and 580 ℃. Then, the – condition reached to the field bounded by the kyanite andalusite and diaspore corundum + HO phase boundaries, forming diaspore at around 0.5 kbar and 350 ℃, and finally, to the kaolinite stability field around 250 ℃ or less.
{"title":"Högbomite and associated minerals within magnetite megacryst in pegmatite from West Ongul Island, East Antarctica","authors":"Toshisuke Kawasaki","doi":"10.1016/j.polar.2025.101301","DOIUrl":"10.1016/j.polar.2025.101301","url":null,"abstract":"<div><div>This is a report of the mineral inclusions in magnetite megacryst within pegmatite, cutting the granulite-facies medium-grained pyroxene gneisses from West Ongul Island, Lützow-Holm Complex, East Antarctica. Inclusions involve a monophase or multiphase assemblage that consists of various combinations of anatase, andalusite, biotite, corundum, diaspore, högbomite, hematite, ilmenite, kaolinite, monazite, muscovite, plagioclase, pseudorutile, quartz, rutile, sillimanite, spinel and zircon. These occur as independent minerals, lamellae, seams, sticks on lamella and seam, aggregates along the magnetite–ilmenite boundary, altered minerals and edge minerals of megacryst.</div><div>West Ongul magnetite crystallised in pegmatite at around 4 kbar and 680 ℃ under hydrous (<span><math><mrow><msub><mrow><mi>f</mi></mrow><mrow><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi></mrow></msub><mo>=</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>12</mn></mrow></msup><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>11</mn></mrow></msup></mrow></math></span> bar) and oxidising (<span><math><mrow><msub><mrow><mi>f</mi></mrow><mrow><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></msub><mo>=</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>17</mn><mo>.</mo><mn>8</mn></mrow></msup><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>12</mn><mo>.</mo><mn>5</mn></mrow></msup></mrow></math></span> bar) conditions. Cooling <span><math><mi>P</mi></math></span>–<span><math><mi>T</mi></math></span> path of pegmatite after magnetite crystallisation is estimated to cut through the wet solidus of muscovite granite at around 3 kbar and 650 ℃. Subsequently, the <span><math><mi>P</mi></math></span>–<span><math><mi>T</mi></math></span> condition changed to the rutile <span><math><mi>⇌</mi></math></span> anatase boundary at around 2 kbar and 580 ℃. Then, the <span><math><mi>P</mi></math></span>–<span><math><mi>T</mi></math></span> condition reached to the field bounded by the kyanite <span><math><mi>⇌</mi></math></span> andalusite and diaspore <span><math><mi>⇌</mi></math></span> corundum + H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O phase boundaries, forming diaspore at around 0.5 kbar and 350 ℃, and finally, to the kaolinite stability field around 250 ℃ or less.</div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"46 ","pages":"Article 101301"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145739147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-06-14DOI: 10.1016/j.polar.2025.101240
Neamat Karimi
Despite Iran's predominantly arid and warm climate, its high mountain elevations host glacier regions, with limited knowledge regarding recent climate-driven surface elevation and mass changes. This study addresses the Takht-e Soleyman glacial area, the largest in Iran, analyzing surface elevation and mass balance changes between 1997 and 2023 using topographic data and UAV surveys. The elevation change data analysis emphasizes the overall trend of glacier surface lowering. The results show a moderate glacier thinning rate, averaging −0.34 ± 0.06 m/a, translating to a mass loss of −0.29 ± 0.05 m w.e.a−1 over 26 years, which is lower than the global average thinning rate of −0.48 ± 0.20 m w.e.a−1. The smaller glaciers in the southern part, such as Merjikesh (−0.03 ± 0.007 m w.e.a−1) and Khersan (−0.24 ± 0.04 m w.e.a−1), displayed more stable mass balances compared to northern glaciers like Alamkouh (−0.31 ± 0.05 m w.e.a−1). A general trend of increased thinning with altitude was observed, with the highest thinning rates in high-altitude accumulation zones. Specifically, the average gradient of lowering for all glaciers in the Takht-e Soleyman region is around −0.06 m/a per 100 m. Climatic trends derived from ERA5 reanalysis data indicate no statistically significant changes in precipitation, snowfall, or temperature, suggesting that regional climate variability is not the primary driver of mass loss. However, snow persistence (derived from MODIS satellite images) exhibited a mean decline of 5 % across the region, with reductions of up to 15 % in critical accumulation zones. Local surface features, including ice cliffs (−0.77 m/a), supraglacial lakes (−0.69 m/a), and debris-free areas (−0.61 m/a), exhibit the highest surface elevation change rates, significantly exceeding the rates observed in debris-covered areas (−0.31 m/a). These findings emphasize that local surface characteristics, rather than climatic variability, are the critical drivers of glacier mass loss in the region. This study enhances understanding of glacier changes in Iran's central Alborz Mountains, highlighting the need for continuous monitoring and regional assessments to better grasp climate change impacts.
尽管伊朗主要是干旱和温暖的气候，但其高海拔地区拥有冰川地区，对最近气候驱动的地表海拔和质量变化的了解有限。本研究针对伊朗最大的Takht-e Soleyman冰川区，利用地形数据和无人机调查分析了1997年至2023年间地表高程和物质平衡的变化。高程变化数据分析强调了冰川表面降低的总体趋势。结果表明，该地区冰川的减薄速率为中等，平均为- 0.34±0.06 m/a， 26年的质量损失量为- 0.29±0.05 m w.e.a−1，低于全球平均的- 0.48±0.20 m w.e.a−1。南部较小的Merjikesh冰川（- 0.03±0.007 m w.e.a−1）和Khersan冰川（- 0.24±0.04 m w.e.a−1）的物质平衡比北部的Alamkouh冰川（- 0.31±0.05 m w.e.a−1）更为稳定。随着海拔高度的增加，总体上有减薄增加的趋势，在高海拔堆积区减薄率最高。具体而言，Takht-e Soleyman地区所有冰川的平均下降梯度约为- 0.06 m/a / 100 m。从ERA5再分析数据得出的气候趋势表明，降水、降雪或温度在统计上没有显著变化，这表明区域气候变率不是质量损失的主要驱动因素。然而，雪持久性（来自MODIS卫星图像）在整个地区平均下降了5%，在关键积累区减少了15%。冰崖（- 0.77 m/a）、冰上湖（- 0.69 m/a）和无碎屑区（- 0.61 m/a）等局部地表特征地表高程变化率最高，显著超过碎屑覆盖区（- 0.31 m/a）。这些发现强调，当地的地表特征，而不是气候变率，是该地区冰川质量损失的关键驱动因素。这项研究加强了对伊朗中部阿尔博尔斯山脉冰川变化的认识，强调了持续监测和区域评估的必要性，以便更好地掌握气候变化的影响。
{"title":"Analysis of mountain glaciers mass loss in Iran's largest glacier region, Takht-e Soleyman, from 1997 to 2023, using the geodetic techniques","authors":"Neamat Karimi","doi":"10.1016/j.polar.2025.101240","DOIUrl":"10.1016/j.polar.2025.101240","url":null,"abstract":"<div><div>Despite Iran's predominantly arid and warm climate, its high mountain elevations host glacier regions, with limited knowledge regarding recent climate-driven surface elevation and mass changes. This study addresses the Takht-e Soleyman glacial area, the largest in Iran, analyzing surface elevation and mass balance changes between 1997 and 2023 using topographic data and UAV surveys. The elevation change data analysis emphasizes the overall trend of glacier surface lowering. The results show a moderate glacier thinning rate, averaging −0.34 ± 0.06 m/a, translating to a mass loss of −0.29 ± 0.05 m w.e.a<sup>−1</sup> over 26 years, which is lower than the global average thinning rate of −0.48 ± 0.20 m w.e.a<sup>−1</sup>. The smaller glaciers in the southern part, such as Merjikesh (−0.03 ± 0.007 m w.e.a<sup>−1</sup>) and Khersan (−0.24 ± 0.04 m w.e.a<sup>−1</sup>), displayed more stable mass balances compared to northern glaciers like Alamkouh (−0.31 ± 0.05 m w.e.a<sup>−1</sup><span><span><span>). A general trend of increased thinning with altitude was observed, with the highest thinning rates in high-altitude accumulation zones. Specifically, the average gradient of lowering for all glaciers in the Takht-e Soleyman region is around −0.06 m/a per 100 m. Climatic trends derived from ERA5 reanalysis data indicate no statistically significant changes in precipitation, snowfall, or temperature, suggesting that regional </span>climate variability is not the primary driver of mass loss. However, snow persistence (derived from </span>MODIS<span> satellite images) exhibited a mean decline of 5 % across the region, with reductions of up to 15 % in critical accumulation zones. Local surface features, including ice cliffs (−0.77 m/a), supraglacial lakes (−0.69 m/a), and debris-free areas (−0.61 m/a), exhibit the highest surface elevation change rates, significantly exceeding the rates observed in debris-covered areas (−0.31 m/a). These findings emphasize that local surface characteristics, rather than climatic variability, are the critical drivers of glacier mass loss in the region. This study enhances understanding of glacier changes in Iran's central Alborz Mountains, highlighting the need for continuous monitoring and regional assessments to better grasp climate change impacts.</span></span></div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"46 ","pages":"Article 101240"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145739058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-08-27DOI: 10.1016/j.polar.2025.101265
Massimo Del Guasta
Antarctica's high latitudes are a challenging place to study precipitation. Despite this, direct monitoring of the habit and size of high-latitude precipitation is crucial for validating the algorithms used to derive precipitation information from radar, and for improving the climatological modeling of polar areas. Precipitation study is primarily done in coastal Antarctica (e.g. Grazioli et al.,2017), while the high plateau lacks long-term direct observation of precipitation. A first statistical analysis of precipitation at Concordia Station (−75°S, 123°E, Antarctica) was performed by Del Guasta et al. (2024) making possible the study, over the period 2014–2021, of the habit-resolved size of ice crystals for ten representative ice habits, the altitude and temperature of formation, and the composition in terms of ice habits for different precipitation sources. In the present work, based on the same data set, the seasonal variations of habit-resolved grain size and habit composition were investigated. The seasonality of diamond dust's contribution to total precipitation was examined. The knowledge of the altitude of precipitation formation allowed the calculation of HYSPLIT backtrajectories for each precipitation event. For the first time, measurements instead of modeling were used to obtain the pathways of precipitation reaching Concordia Station. The seasonal variations of these pathways were also examined.
{"title":"The seasonality of precipitation on the eastern Antarctic plateau (Dome-C) as derived from LIDAR and ICECAMERA","authors":"Massimo Del Guasta","doi":"10.1016/j.polar.2025.101265","DOIUrl":"10.1016/j.polar.2025.101265","url":null,"abstract":"<div><div>Antarctica's high latitudes are a challenging place to study precipitation. Despite this, direct monitoring of the habit and size of high-latitude precipitation is crucial for validating the algorithms used to derive precipitation information from radar, and for improving the climatological modeling of polar areas. Precipitation study is primarily done in coastal Antarctica (e.g. Grazioli et al.,2017), while the high plateau lacks long-term direct observation of precipitation. A first statistical analysis of precipitation at Concordia Station (−75°S, 123°E, Antarctica) was performed by Del Guasta et al. (2024) making possible the study, over the period 2014–2021, of the habit-resolved size of ice crystals for ten representative ice habits, the altitude and temperature of formation, and the composition in terms of ice habits for different precipitation sources. In the present work, based on the same data set, the seasonal variations of habit-resolved grain size and habit composition were investigated. The seasonality of diamond dust's contribution to total precipitation was examined. The knowledge of the altitude of precipitation formation allowed the calculation of HYSPLIT backtrajectories for each precipitation event. For the first time, measurements instead of modeling were used to obtain the pathways of precipitation reaching Concordia Station. The seasonal variations of these pathways were also examined.</div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"46 ","pages":"Article 101265"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145739094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In several regions in the Arctic, scientific knowledge to assess and predict the impacts of environmental changes is insufficient, due to its remoteness and the challenging conditions for conducting surveys. Here, we listened to and documented the stories of the lives of Indigenous people living around Inglefield Bredning, northwest Greenland, to understand the environmental and ecological changes occurring in this area, and the impact of these changes on their lives. Our study introduces scientifically-undocumented environmental and ecological changes in this region such as an increase in Atlantic species, and suggests that these changes are interrelated and occur as part of a chain reaction, rather than in isolation. Through this study, we emphasize the necessity of a multifaceted approach for a better understanding of the complex intertwining of environmental, ecological, cultural, and social changes to develop effective and sustainable management.
{"title":"The situation of Inuit communities in northwest Greenland (Kalaallit Nunaat) amid continuously changing environmental and social conditions","authors":"Monica Ogawa , Ryo Kusaka , Shin Sugiyama , Yoko Mitani","doi":"10.1016/j.polar.2025.101257","DOIUrl":"10.1016/j.polar.2025.101257","url":null,"abstract":"<div><div>In several regions in the Arctic, scientific knowledge to assess and predict the impacts of environmental changes is insufficient, due to its remoteness and the challenging conditions for conducting surveys. Here, we listened to and documented the stories of the lives of Indigenous people living around Inglefield Bredning, northwest Greenland, to understand the environmental and ecological changes occurring in this area, and the impact of these changes on their lives. Our study introduces scientifically-undocumented environmental and ecological changes in this region such as an increase in Atlantic species, and suggests that these changes are interrelated and occur as part of a chain reaction, rather than in isolation. Through this study, we emphasize the necessity of a multifaceted approach for a better understanding of the complex intertwining of environmental, ecological, cultural, and social changes to develop effective and sustainable management.</div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"46 ","pages":"Article 101257"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145739074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-07DOI: 10.1016/j.polar.2025.101307
P.V. Thanooja , K. Sajeev , M. Satish-Kumar , I.S. Williams , T. Takahashi , C. Chatterjee
This study investigates the Neoarchean tectonic evolution of the Madras Block through various analyses of felsic orthogneiss and associated amphibolites. The felsic orthogneiss has high SiO2 (∼67 wt%), LREE enrichment, high Ba (∼560 ppm) contents and high Sr/Y (∼96) ratios, with low MgO (∼1.60 wt%) and Y (∼7.1 ppm) contents, along with a highly fractionated REE profile (La/YbN ≈ 42), all suggesting an affinity with the Archean TTG suite. The amphibolites show geochemical diversity, with enclave samples displaying a MORB-like flat REE pattern, while larger outcrop-scale blocks exhibit LREE enrichment, resembling continental crust. Zircon U-Pb dating suggests that the felsic rocks of the Madras Block were emplaced over a short time span (2.57–2.51 Ga), and that this magmatic activity was closely followed by regional high-grade metamorphism. The Nd-Sr Isotopic ratios (143Nd/144Ndi: 0.509056–0.509359; 87Sr/86Sri: 0.7016–0.7033) and ɛNd(T) values (−4.3 to +0.4) indicate significant crust-mantle interactions. The felsic orthogneiss of the Madras Block was probably formed by a multi-stage petrogenetic process involving subduction-related partial melting of a MORB-like oceanic crust, followed by interaction with the mantle wedge and underplating of mafic magmas. Subsequent partial melting of the underplated basaltic crust and mixing with older continental components contributed to the generation of evolved felsic magmas. This model highlights the role of subduction, mantle–crust interaction, and deep crustal reworking in the formation of late Neoarchean continental crust.
{"title":"Neoarchean crustal evolution in the Madras Block: Geochemical and petrological evidence from felsic gneiss and amphibolite","authors":"P.V. Thanooja , K. Sajeev , M. Satish-Kumar , I.S. Williams , T. Takahashi , C. Chatterjee","doi":"10.1016/j.polar.2025.101307","DOIUrl":"10.1016/j.polar.2025.101307","url":null,"abstract":"<div><div>This study investigates the Neoarchean tectonic evolution of the Madras Block through various analyses of felsic orthogneiss and associated amphibolites. The felsic orthogneiss has high SiO<sub>2</sub> (∼67 wt%), LREE enrichment, high Ba (∼560 ppm) contents and high Sr/Y (∼96) ratios, with low MgO (∼1.60 wt%) and Y (∼7.1 ppm) contents, along with a highly fractionated REE profile (La/Yb<sub>N</sub> ≈ 42), all suggesting an affinity with the Archean TTG suite. The amphibolites show geochemical diversity, with enclave samples displaying a MORB-like flat REE pattern, while larger outcrop-scale blocks exhibit LREE enrichment, resembling continental crust. Zircon U-Pb dating suggests that the felsic rocks of the Madras Block were emplaced over a short time span (2.57–2.51 Ga), and that this magmatic activity was closely followed by regional high-grade metamorphism. The Nd-Sr Isotopic ratios (<sup>143</sup>Nd/<sup>144</sup>Ndi: 0.509056–0.509359; <sup>87</sup>Sr/<sup>86</sup>Sri: 0.7016–0.7033) and ɛNd(T) values (−4.3 to +0.4) indicate significant crust-mantle interactions. The felsic orthogneiss of the Madras Block was probably formed by a multi-stage petrogenetic process involving subduction-related partial melting of a MORB-like oceanic crust, followed by interaction with the mantle wedge and underplating of mafic magmas. Subsequent partial melting of the underplated basaltic crust and mixing with older continental components contributed to the generation of evolved felsic magmas. This model highlights the role of subduction, mantle–crust interaction, and deep crustal reworking in the formation of late Neoarchean continental crust.</div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"46 ","pages":"Article 101307"},"PeriodicalIF":2.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145739151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The second phase of the Arctic Challenge for Sustainability (ArCS II) project funded by the Japanese government was launched in June 2020. The Ocean Research Program of this project was engaged in research on Arctic marine environments and production of corresponding public datasets. Sub-program 1 was established to explore ocean heat/freshwater transport and biogeochemical cycles in seasonal and multi-year sea ice zones. Sub-program 2 focused on assessment of the vulnerability and resilience of marine ecosystems in response to rapid sea ice retreat. Sub-program 3 examined air–sea interactions related to sea ice and waves. The expected outcomes included refinement of Earth System Models, advancement of ecosystem-based fishery management, and development of safer maritime navigation. This article compiles the major findings of sub-programs 1 and 3, together with brief summaries on the research cruises, sea ice field campaigns, and modeling experiments conducted through various international collaborations. The scientific achievements of the ArCS II research activities foster a deeper understanding of the effects of climate change and provide information for socioeconomic benefit.
{"title":"Arctic marine environments regulated by ocean transport and air‒sea‒land interaction: Findings from the ArCS II Ocean Research Program","authors":"Eiji Watanabe , Hiromichi Ueno , Tsubasa Kodaira , Akihiko Murata , Shigeto Nishino , Takahito Ikenoue , Masanobu Yamamoto , Daiki Nomura , Hiroto Abe , Yusuke Kawaguchi , Daisuke Hirano , Yuanxin Zhang , Sayaka Yasunaka","doi":"10.1016/j.polar.2025.101205","DOIUrl":"10.1016/j.polar.2025.101205","url":null,"abstract":"<div><div>The second phase of the Arctic Challenge for Sustainability (ArCS II) project funded by the Japanese government was launched in June 2020. The Ocean Research Program of this project was engaged in research on Arctic marine environments and production of corresponding public datasets. Sub-program 1 was established to explore ocean heat/freshwater transport and biogeochemical cycles in seasonal and multi-year sea ice zones. Sub-program 2 focused on assessment of the vulnerability and resilience of marine ecosystems in response to rapid sea ice retreat. Sub-program 3 examined air–sea interactions related to sea ice and waves. The expected outcomes included refinement of Earth System Models, advancement of ecosystem-based fishery management, and development of safer maritime navigation. This article compiles the major findings of sub-programs 1 and 3, together with brief summaries on the research cruises, sea ice field campaigns, and modeling experiments conducted through various international collaborations. The scientific achievements of the ArCS II research activities foster a deeper understanding of the effects of climate change and provide information for socioeconomic benefit.</div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"45 ","pages":"Article 101205"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145335205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01Epub Date: 2025-06-04DOI: 10.1016/j.polar.2025.101216
M. Koike , M. Takigawa , S. Morimoto , K. Adachi , T. Aizawa , N. Chandra , R. Fujita , D. Goto , S. Ishidoya , K. Ishijima , A. Ito , K. Kawai , Y. Kanaya , Y. Kim , T. Kinase , Y. Kondo , T. Machida , H. Matsui , T. Miyakawa , M. Mochida , C. Zhu
This paper reviews studies of atmospheric climate forcers, namely, greenhouse gases (GHGs) and aerosols, and their impacts on radiation and clouds in the Arctic during the Arctic Challenge for Sustainability II (ArCS II) project conducted between 2020 and 2024. In GHG research, we measured atmospheric mixing ratios of CO2, CH4, and N2O and their isotope ratios, as well as O2/N2 ratios from the ground, ship (research vessel Mirai), and commercial aircraft over the northern high latitudes. We showed that the rapid increase of CH4 mixing ratios after ∼2018 could be attributed to elevated microbial CH4 emissions. The increase of N2O after ∼2011 was attributable to an increase of N2O emissions from soil treated with chemical fertilizer. In aerosol research, we provided a scientific basis for constructing unified black carbon (BC) datasets in the Arctic and estimated the contributions to Arctic BC from biomass-burning and anthropogenic sources in various regions. We showed the abundance of highly active ice nucleating particles (INPs) increased with rising surface temperatures above 0 °C and evaluated impacts of Arctic dust that serve as INP on clouds. We found that marine biota were likely the sources of cloud condensation nuclei and INPs over the remote Arctic Ocean during periods of high biological activity.
{"title":"Studies of atmospheric climate forcers in the Arctic during the ArCS II project","authors":"M. Koike , M. Takigawa , S. Morimoto , K. Adachi , T. Aizawa , N. Chandra , R. Fujita , D. Goto , S. Ishidoya , K. Ishijima , A. Ito , K. Kawai , Y. Kanaya , Y. Kim , T. Kinase , Y. Kondo , T. Machida , H. Matsui , T. Miyakawa , M. Mochida , C. Zhu","doi":"10.1016/j.polar.2025.101216","DOIUrl":"10.1016/j.polar.2025.101216","url":null,"abstract":"<div><div><span>This paper reviews studies of atmospheric climate forcers, namely, greenhouse gases (GHGs) and aerosols, and their impacts on radiation and clouds in the Arctic during the Arctic Challenge for Sustainability II (ArCS II) project conducted between 2020 and 2024. In GHG research, we measured atmospheric mixing ratios of CO</span><sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub><span>O and their isotope ratios, as well as O</span><sub>2</sub>/N<sub>2</sub> ratios from the ground, ship (research vessel <em>Mirai</em>), and commercial aircraft over the northern high latitudes. We showed that the rapid increase of CH<sub>4</sub> mixing ratios after ∼2018 could be attributed to elevated microbial CH<sub>4</sub> emissions. The increase of N<sub>2</sub>O after ∼2011 was attributable to an increase of N<sub>2</sub><span>O emissions from soil treated with chemical fertilizer<span><span><span>. In aerosol research, we provided a scientific basis for constructing unified black carbon (BC) datasets in the Arctic and estimated the contributions to Arctic BC from biomass-burning and anthropogenic sources in various regions. We showed the abundance of highly active ice nucleating particles (INPs) increased with rising surface temperatures above 0 °C and evaluated impacts of Arctic dust that serve as INP on clouds. We found that </span>marine biota were likely the sources of </span>cloud condensation nuclei<span> and INPs over the remote Arctic Ocean during periods of high biological activity.</span></span></span></div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"45 ","pages":"Article 101216"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145335204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01Epub Date: 2025-01-09DOI: 10.1016/j.polar.2025.101164
Hideki Kobayashi , Masaki Uchida , Tetsuo Sueyoshi , Shota Masumoto , Shu-Kuan Wong , Keita Nishizawa , Naoto Shinohara , Akira S. Mori , Masahito Ueyama , Keiko Konya , Tetsuya Hiyama , Hironari Kanamori , Kazuyuki Saito , Tokuta Yokohata , Hotaek Park , Xinyu Xu
The terrestrial program of the Arctic Challenge for Sustainability-II (ArCS II) is dedicated to clarifying the complex responses of Arctic boreal ecosystems and biogeochemical cycles to a warming climate. Focusing on ecosystem function, terrestrial greenhouse gas dynamics, and permafrost and biogeochemical cycles, ArCS II targets key challenges posed by climate change across terrestrial ecosystems. Biodiversity and ecosystem function research emphasizes the interactions between plant and soil microbial communities across Arctic boreal regions, with discoveries such as new fungal species contributing valuable information elucidating the status of Arctic ecosystems. Our study revealed that vegetation has a significant impact on the composition and network structure of microbial communities, and these interactions may influence ecosystem responses to environmental changes. Greenhouse gas dynamics were analyzed using long-term carbon and methane emissions data collected in boreal forests, tundra, wetlands, and glacial termini, as emissions from these regions can accelerate warming. Plant-mediated methane transport was identified as the primary process driving methane emission from wetlands, and elevated methane concentrations were detected in some glacial meltwaters. ArCS II advances permafrost modeling to assess the impacts of thawing on terrestrial processes, emphasizing freeze–thaw cycles and their impact on greenhouse gas dynamics. Excess ice formed within permafrost plays a role in suppressing permafrost warming and may induce anomalous variations in greenhouse gas emissions. Despite limitations imposed on field surveys by COVID-19, the ArCS II project elucidated ecosystem changes using long-term data. ArCS II terrestrial research lays a foundation for the exploration of climate impacts on Arctic boreal ecosystems.
{"title":"Studies of arctic–boreal ecosystem function and biogeochemical cycles in the ArCS II terrestrial program","authors":"Hideki Kobayashi , Masaki Uchida , Tetsuo Sueyoshi , Shota Masumoto , Shu-Kuan Wong , Keita Nishizawa , Naoto Shinohara , Akira S. Mori , Masahito Ueyama , Keiko Konya , Tetsuya Hiyama , Hironari Kanamori , Kazuyuki Saito , Tokuta Yokohata , Hotaek Park , Xinyu Xu","doi":"10.1016/j.polar.2025.101164","DOIUrl":"10.1016/j.polar.2025.101164","url":null,"abstract":"<div><div><span><span>The terrestrial program of the Arctic Challenge for Sustainability-II (ArCS II) is dedicated to clarifying the complex responses of Arctic boreal ecosystems and biogeochemical cycles<span><span> to a warming climate. Focusing on ecosystem function, terrestrial greenhouse gas dynamics, and permafrost and </span>biogeochemical cycles<span>, ArCS II targets key challenges posed by climate change across </span></span></span>terrestrial ecosystems. Biodiversity and ecosystem function research emphasizes the interactions between plant and soil </span>microbial communities<span> across Arctic boreal regions, with discoveries such as new fungal species contributing valuable information elucidating the status of Arctic ecosystems<span><span>. Our study revealed that vegetation has a significant impact on the composition and network structure of microbial communities<span>, and these interactions may influence ecosystem responses to environmental changes. Greenhouse gas dynamics were analyzed using long-term carbon and methane emissions data collected in boreal forests, tundra, wetlands, and glacial termini, as emissions from these regions can accelerate warming. Plant-mediated methane transport was identified as the primary process driving methane emission from wetlands, and elevated methane concentrations were detected in some glacial </span></span>meltwaters<span>. ArCS II advances permafrost modeling to assess the impacts of thawing on terrestrial processes, emphasizing freeze–thaw cycles and their impact on greenhouse gas dynamics. Excess ice formed within permafrost plays a role in suppressing permafrost warming and may induce anomalous variations in greenhouse gas emissions. Despite limitations imposed on field surveys by COVID-19, the ArCS II project elucidated ecosystem changes using long-term data. ArCS II terrestrial research lays a foundation for the exploration of climate impacts on Arctic boreal ecosystems.</span></span></span></div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"45 ","pages":"Article 101164"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145335208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01Epub Date: 2025-09-08DOI: 10.1016/j.polar.2025.101268
Motoyoshi Ikeda
ArCS II (Arctic Challenge for Sustainability II) Project was a Japanese national research project on Arctic change that lasted approximately five years from June 2020 to March 2025. ArCS II was to promote advanced research, such as understanding environmental change in the Arctic region, clarifying its processes, and improving weather forecasting, to realize a sustainable society. The project assessed the impact of significant environmental changes in the Arctic on human society, including Japan, and provided stakeholders with basic scientific knowledge for legal and policy responses to rule-making in the Arctic, to realize the results of this research in society. Research subjects ranged from natural sciences to the humanities and social sciences, engineering, and international law and policy. This special issue introduces the activities and achievements of ArCS II through nine review articles covering a wide range of fields.
{"title":"Arctic Challenge for Sustainability II (ArCS II) project","authors":"Motoyoshi Ikeda","doi":"10.1016/j.polar.2025.101268","DOIUrl":"10.1016/j.polar.2025.101268","url":null,"abstract":"<div><div>ArCS II (Arctic Challenge for Sustainability II) Project was a Japanese national research project on Arctic change that lasted approximately five years from June 2020 to March 2025. ArCS II was to promote advanced research, such as understanding environmental change in the Arctic region, clarifying its processes, and improving weather forecasting, to realize a sustainable society. The project assessed the impact of significant environmental changes in the Arctic on human society, including Japan, and provided stakeholders with basic scientific knowledge for legal and policy responses to rule-making in the Arctic, to realize the results of this research in society. Research subjects ranged from natural sciences to the humanities and social sciences, engineering, and international law and policy. This special issue introduces the activities and achievements of ArCS II through nine review articles covering a wide range of fields.</div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"45 ","pages":"Article 101268"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145335210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Coastal environments in the Arctic are increasingly affected by the rapidly changing climate. Significant and complex impacts of atmospheric warming have been intensifying, with changes observed both in terrestrial and marine environments. Here, we describe the overview and highlight the study results of multidisciplinary research activities performed under the ArCS II project (Arctic Challenge for Sustainability II) in the Qaanaaq coastal region of northwestern Greenland. The Japanese Arctic projects GRENE-Arctic and ArCS have conducted research at this study site since 2012. In continuity with these previous efforts, field and satellite measurements were carried out to quantify glacier and ice sheet changes. Fish, marine mammals and seabirds, which are key natural resources to human livelihoods, were studied in collaboration with local fishermen and hunters to examine habitat use and clarify the potential responses of marine ecosystems to the changing environments. Greenlandic villages are also directly affected by the flooding of glacial streams and landslides, which were monitored to better understand the driving mechanisms and risks to Arctic societies in the future. Research was also carried out in Qaanaaq village to investigate waste management and housing conditions. The study results were shared with residents through workshops that took place in Qaanaaq and nearby smaller villages. Our results show that coastal environments in northwestern Greenland are changing with increasingly evident impact on human livelihoods. Further collaboration with the villagers, notably in co-designing research questions and interests, is crucial to anticipate, reduce and mitigate the impacts of environmental changes on Arctic communities.
{"title":"Changes in the coastal environments and their impact on society in the Qaanaaq region, northwestern Greenland","authors":"Shin Sugiyama , Atsushi Yamaguchi , Tatsuya Watanabe , Yasumasa Tojo , Naotaka Hayashi , Jean-Baptiste Thiebot , Makoto Tomiyasu , Kohei Hasegawa , Yoko Mitani , Mayuko Otsuki , Yuta Sakuragi , Monica Ogawa , Kenzo Tanaka , Kaisei Sakurai , Kohei Matsuno , Naoya Kanna , Evgeny Podolskiy , Ryo Kusaka , Yefan Wang , Takuro Imazu , Toku Oshima","doi":"10.1016/j.polar.2025.101206","DOIUrl":"10.1016/j.polar.2025.101206","url":null,"abstract":"<div><div>Coastal environments in the Arctic are increasingly affected by the rapidly changing climate. Significant and complex impacts of atmospheric warming have been intensifying, with changes observed both in terrestrial and marine environments. Here, we describe the overview and highlight the study results of multidisciplinary research activities performed under the ArCS II project (Arctic Challenge for Sustainability II) in the Qaanaaq coastal region of northwestern Greenland. The Japanese Arctic projects GRENE-Arctic and ArCS have conducted research at this study site since 2012. In continuity with these previous efforts, field and satellite measurements were carried out to quantify glacier and ice sheet changes. Fish, marine mammals and seabirds, which are key natural resources to human livelihoods, were studied in collaboration with local fishermen and hunters to examine habitat use and clarify the potential responses of marine ecosystems to the changing environments. Greenlandic villages are also directly affected by the flooding of glacial streams and landslides, which were monitored to better understand the driving mechanisms and risks to Arctic societies in the future. Research was also carried out in Qaanaaq village to investigate waste management and housing conditions. The study results were shared with residents through workshops that took place in Qaanaaq and nearby smaller villages. Our results show that coastal environments in northwestern Greenland are changing with increasingly evident impact on human livelihoods. Further collaboration with the villagers, notably in co-designing research questions and interests, is crucial to anticipate, reduce and mitigate the impacts of environmental changes on Arctic communities.</div></div>","PeriodicalId":20316,"journal":{"name":"Polar Science","volume":"45 ","pages":"Article 101206"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145335212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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