Pub Date : 2025-11-05DOI: 10.1038/s41561-025-01812-2
Jonathan Jung, Nicolas N. Duprey, Alan D. Foreman, Juan Pablo D’Olivo, Carolin Pellio, Yeongjun Ryu, Erin L. Murphy, Baseerat Romshoo, Diego K. Kersting, Gabriel O. Cardoso, Tanja Wald, François Fripiat, Carlos Jimenez, Eberhard Gischler, Paolo Montagna, Carlos Alonso-Hernández, Miguel Gomez-Batista, Christina Treinen-Crespo, José Carriquiry, Maria Rosabelle Ong, Nathalie F. Goodkin, Reia Guppy, Hedy Aardema, Hans Slagter, Lena Heins, Isabella Hrabe de Angelis, Aaron L. Bieler, Maayan Yehudai, Trevor P. Noël, Kendon James, Denis Scholz, Chuanmin Hu, Brian B. Barnes, Andrea Pozzer, Christopher Pöhlker, Jos Lelieveld, Ulrich Pöschl, Hubert Vonhof, Gerald H. Haug, Ralf Schiebel, Daniel M. Sigman, Alfredo Martínez-García
The Great Atlantic Sargassum Belt first appeared in 2011 and quickly became the largest interconnected floating biome on Earth. In recent years, Sargassum stranding events have caused substantial ecological and socio-economic impacts in coastal communities. Sargassum requires both phosphorus (P) and nitrogen (N) for growth, yet the primary sources of these nutrients fuelling the extensive Sargassum blooms remain unclear. Here we use coral-bound N isotopes to reconstruct N2 fixation, the ultimate source of the ocean’s bioavailable N, across the Caribbean over the past 120 years. Our data indicate that changes in N2 fixation were primarily controlled by multidecadal and interannual changes in equatorial Atlantic upwelling of ‘excess P’, that is, P in stoichiometric excess relative to fixed N. We show that the supply of excess P from equatorial upwelling and N from the N2 fixation response can account for the majority of Sargassum variability since 2011. Sargassum dynamics are best explained by their symbiosis with N2-fixing epiphytes, which render the macroalgae highly competitive during strong equatorial upwelling of excess P. Thus, the future of Sargassum in the tropical Atlantic will depend on how global warming affects equatorial Atlantic upwelling and the climatic modes that control it. High near-surface nitrogen-fixation rates that promoted the recent growth of the Great Atlantic Sargassum Belt were tied to greater upwelling of phosphorus from the equatorial Atlantic, according to coral-bound nitrogen isotope records from the Caribbean.
{"title":"Equatorial upwelling of phosphorus drives Atlantic N2 fixation and Sargassum blooms","authors":"Jonathan Jung, Nicolas N. Duprey, Alan D. Foreman, Juan Pablo D’Olivo, Carolin Pellio, Yeongjun Ryu, Erin L. Murphy, Baseerat Romshoo, Diego K. Kersting, Gabriel O. Cardoso, Tanja Wald, François Fripiat, Carlos Jimenez, Eberhard Gischler, Paolo Montagna, Carlos Alonso-Hernández, Miguel Gomez-Batista, Christina Treinen-Crespo, José Carriquiry, Maria Rosabelle Ong, Nathalie F. Goodkin, Reia Guppy, Hedy Aardema, Hans Slagter, Lena Heins, Isabella Hrabe de Angelis, Aaron L. Bieler, Maayan Yehudai, Trevor P. Noël, Kendon James, Denis Scholz, Chuanmin Hu, Brian B. Barnes, Andrea Pozzer, Christopher Pöhlker, Jos Lelieveld, Ulrich Pöschl, Hubert Vonhof, Gerald H. Haug, Ralf Schiebel, Daniel M. Sigman, Alfredo Martínez-García","doi":"10.1038/s41561-025-01812-2","DOIUrl":"10.1038/s41561-025-01812-2","url":null,"abstract":"The Great Atlantic Sargassum Belt first appeared in 2011 and quickly became the largest interconnected floating biome on Earth. In recent years, Sargassum stranding events have caused substantial ecological and socio-economic impacts in coastal communities. Sargassum requires both phosphorus (P) and nitrogen (N) for growth, yet the primary sources of these nutrients fuelling the extensive Sargassum blooms remain unclear. Here we use coral-bound N isotopes to reconstruct N2 fixation, the ultimate source of the ocean’s bioavailable N, across the Caribbean over the past 120 years. Our data indicate that changes in N2 fixation were primarily controlled by multidecadal and interannual changes in equatorial Atlantic upwelling of ‘excess P’, that is, P in stoichiometric excess relative to fixed N. We show that the supply of excess P from equatorial upwelling and N from the N2 fixation response can account for the majority of Sargassum variability since 2011. Sargassum dynamics are best explained by their symbiosis with N2-fixing epiphytes, which render the macroalgae highly competitive during strong equatorial upwelling of excess P. Thus, the future of Sargassum in the tropical Atlantic will depend on how global warming affects equatorial Atlantic upwelling and the climatic modes that control it. High near-surface nitrogen-fixation rates that promoted the recent growth of the Great Atlantic Sargassum Belt were tied to greater upwelling of phosphorus from the equatorial Atlantic, according to coral-bound nitrogen isotope records from the Caribbean.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 12","pages":"1259-1265"},"PeriodicalIF":16.1,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01812-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145440916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-05DOI: 10.1038/s41561-025-01841-x
Max K. Lloyd, Rebekah S. Sprengel, Barbara E. Wortham, Regan E. Dunn, Daniel E. Ibarra, Todd E. Dawson, Daniel A. Stolper
Low atmospheric carbon dioxide levels are thought to suppress land plant productivity in part by promoting photorespiration, wherein illuminated C3 plants uptake molecular oxygen and release carbon dioxide. This could act as a negative feedback that limits atmospheric carbon dioxide decline during glacial periods. However, colder glacial temperatures would suppress photorespiration, potentially counteracting this feedback. Here we tested the hypothesis that land plants photorespired more during glacial periods by applying a proxy for photorespiration rate based on clumped isotope compositions of wood methoxyl groups, validated in modern and recent trees, to North American subfossil tree specimens from the last glacial period. We find that, across most of ice-free North America, trees from the last glacial period photorespired more than more recent trees from similar locations and more than contemporary trees from higher latitudes. We reconcile these differences using a single model relationship between temperature, atmospheric carbon dioxide levels and photorespiration, which suggests that, during glacial periods, photorespiration increased primarily in warmer growing environments that cooled by about 6 °C or less. This supports the hypothesis of a negative feedback that regulates atmospheric carbon dioxide by increasing photorespiration and restricting land plant productivity during glacial periods. Low carbon dioxide levels during the last glacial period enhanced photorespiration in trees across North America, indicating a decline in land plant productivity, according to measurements of clumped isotopes in subfossil wood samples.
{"title":"Isotopic evidence for elevated photorespiration during the last glacial period","authors":"Max K. Lloyd, Rebekah S. Sprengel, Barbara E. Wortham, Regan E. Dunn, Daniel E. Ibarra, Todd E. Dawson, Daniel A. Stolper","doi":"10.1038/s41561-025-01841-x","DOIUrl":"10.1038/s41561-025-01841-x","url":null,"abstract":"Low atmospheric carbon dioxide levels are thought to suppress land plant productivity in part by promoting photorespiration, wherein illuminated C3 plants uptake molecular oxygen and release carbon dioxide. This could act as a negative feedback that limits atmospheric carbon dioxide decline during glacial periods. However, colder glacial temperatures would suppress photorespiration, potentially counteracting this feedback. Here we tested the hypothesis that land plants photorespired more during glacial periods by applying a proxy for photorespiration rate based on clumped isotope compositions of wood methoxyl groups, validated in modern and recent trees, to North American subfossil tree specimens from the last glacial period. We find that, across most of ice-free North America, trees from the last glacial period photorespired more than more recent trees from similar locations and more than contemporary trees from higher latitudes. We reconcile these differences using a single model relationship between temperature, atmospheric carbon dioxide levels and photorespiration, which suggests that, during glacial periods, photorespiration increased primarily in warmer growing environments that cooled by about 6 °C or less. This supports the hypothesis of a negative feedback that regulates atmospheric carbon dioxide by increasing photorespiration and restricting land plant productivity during glacial periods. Low carbon dioxide levels during the last glacial period enhanced photorespiration in trees across North America, indicating a decline in land plant productivity, according to measurements of clumped isotopes in subfossil wood samples.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 12","pages":"1232-1238"},"PeriodicalIF":16.1,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145441140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-11-04DOI: 10.1038/s41561-025-01851-9
Our analysis of mineral deposits in a cave in North Greenland reveals a sensitive High Arctic Late Miocene climate at moderate CO2 levels, balanced between wetter and warmer permafrost-free conditions and ephemeral glacier expansion.
{"title":"Caves record permafrost-free North Greenland under moderate Late Miocene CO2 levels","authors":"","doi":"10.1038/s41561-025-01851-9","DOIUrl":"10.1038/s41561-025-01851-9","url":null,"abstract":"Our analysis of mineral deposits in a cave in North Greenland reveals a sensitive High Arctic Late Miocene climate at moderate CO2 levels, balanced between wetter and warmer permafrost-free conditions and ephemeral glacier expansion.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 12","pages":"1194-1195"},"PeriodicalIF":16.1,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145434344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-11-03DOI: 10.1038/s41561-025-01802-4
Naomi Ochwat, Ted Scambos, Robert S. Anderson, J. Paul Winberry, Adrian Luckman, Etienne Berthier, Maud Bernat, Yulia K. Antropova
Understanding and predicting marine-terminating glacier instability presents one of the greatest challenges to forecasting future sea level rise. An extreme case of such instability is the Hektoria Glacier on the Eastern Antarctic Peninsula, which retreated ~25 km between January 2022 and March 2023. Here we investigate the dynamics and drivers of this retreat event primarily from analysis of geophysical data and satellite imagery. We find that retreat commenced immediately after the loss of decade-old fast ice in the Larsen B embayment and was associated with an almost 6-fold increase in flow speed and 40-fold increase in glacier thinning, relative to the period immediately before the fast ice loss. We also find that in November–December 2022, the glacier retreated a total of 8.2 ± 0.2 km in two months—a retreat rate nearly an order of magnitude faster than published values—and began with a transition from tabular iceberg calving to buoyancy-driven calving on an ice plain, a flat area where the glacier was only lightly grounded. Hence we conclude that in this case, retreat primarily resulted from an ice plain calving process, rather than atmospheric or oceanic conditions as suggested previously. This implies that marine-terminating glaciers with ice plain bed geometry can be easily destabilized. An Antarctic glacier retreated after the loss of landfast ice at a peak rate almost an order of magnitude faster than previously recorded because of buoyancy-driven ice calving, according to an analysis of geophysical data and satellite imagery.
{"title":"Record grounded glacier retreat caused by an ice plain calving process","authors":"Naomi Ochwat, Ted Scambos, Robert S. Anderson, J. Paul Winberry, Adrian Luckman, Etienne Berthier, Maud Bernat, Yulia K. Antropova","doi":"10.1038/s41561-025-01802-4","DOIUrl":"10.1038/s41561-025-01802-4","url":null,"abstract":"Understanding and predicting marine-terminating glacier instability presents one of the greatest challenges to forecasting future sea level rise. An extreme case of such instability is the Hektoria Glacier on the Eastern Antarctic Peninsula, which retreated ~25 km between January 2022 and March 2023. Here we investigate the dynamics and drivers of this retreat event primarily from analysis of geophysical data and satellite imagery. We find that retreat commenced immediately after the loss of decade-old fast ice in the Larsen B embayment and was associated with an almost 6-fold increase in flow speed and 40-fold increase in glacier thinning, relative to the period immediately before the fast ice loss. We also find that in November–December 2022, the glacier retreated a total of 8.2 ± 0.2 km in two months—a retreat rate nearly an order of magnitude faster than published values—and began with a transition from tabular iceberg calving to buoyancy-driven calving on an ice plain, a flat area where the glacier was only lightly grounded. Hence we conclude that in this case, retreat primarily resulted from an ice plain calving process, rather than atmospheric or oceanic conditions as suggested previously. This implies that marine-terminating glaciers with ice plain bed geometry can be easily destabilized. An Antarctic glacier retreated after the loss of landfast ice at a peak rate almost an order of magnitude faster than previously recorded because of buoyancy-driven ice calving, according to an analysis of geophysical data and satellite imagery.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 11","pages":"1117-1124"},"PeriodicalIF":16.1,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145434352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-11-03DOI: 10.1038/s41561-025-01835-9
Analysis of satellite remote sensing and geophysical data reveals that following the loss of stabilizing fast ice, an Antarctic Peninsula glacier retreated at a record pace due to a fast calving and flotation process that occurred as it reached an ‘ice plain’, where the ice is lightly resting on bedrock.
{"title":"Antarctic glacier retreats at record rate due to rapid flotation and calving process","authors":"","doi":"10.1038/s41561-025-01835-9","DOIUrl":"10.1038/s41561-025-01835-9","url":null,"abstract":"Analysis of satellite remote sensing and geophysical data reveals that following the loss of stabilizing fast ice, an Antarctic Peninsula glacier retreated at a record pace due to a fast calving and flotation process that occurred as it reached an ‘ice plain’, where the ice is lightly resting on bedrock.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 11","pages":"1093-1094"},"PeriodicalIF":16.1,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145434353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-10-30DOI: 10.1038/s41561-025-01833-x
Dong Chen, David P. Roy, Zhe Zhu, Tim R. McVicar, Justin Sheffield, Peter M. Atkinson, Amir AghaKouchak, Thomas Blaschke, Pasquale Borrelli, Wouter Dorigo, Rasmus Fensholt, Noel Gorelick, Luis Guanter, Klaus Hubacek, Matthew F. McCabe, Diego G. Miralles, Anja Rammig, Markus Reichstein, Eric Rignot, Brendan M. Rogers, Alexandra Tyukavina, Sander Veraverbeke, Pablo J. Zarco-Tejada, Etienne Berthier
Greater accessibility to China’s vast archive of satellite Earth observations could enhance scientific progress, disaster preparedness, and international cooperation.
更广泛地获取中国庞大的卫星地球观测档案，可以促进科学进步、备灾和国际合作。
{"title":"A call for integrated and cooperative global sharing of China’s Earth observation data","authors":"Dong Chen, David P. Roy, Zhe Zhu, Tim R. McVicar, Justin Sheffield, Peter M. Atkinson, Amir AghaKouchak, Thomas Blaschke, Pasquale Borrelli, Wouter Dorigo, Rasmus Fensholt, Noel Gorelick, Luis Guanter, Klaus Hubacek, Matthew F. McCabe, Diego G. Miralles, Anja Rammig, Markus Reichstein, Eric Rignot, Brendan M. Rogers, Alexandra Tyukavina, Sander Veraverbeke, Pablo J. Zarco-Tejada, Etienne Berthier","doi":"10.1038/s41561-025-01833-x","DOIUrl":"10.1038/s41561-025-01833-x","url":null,"abstract":"Greater accessibility to China’s vast archive of satellite Earth observations could enhance scientific progress, disaster preparedness, and international cooperation.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 11","pages":"1071-1073"},"PeriodicalIF":16.1,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145397198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-10-27DOI: 10.1038/s41561-025-01823-z
Eva Bucciarelli, Pierrick Penven, Stéphane Pous, Alessandro Tagliabue
A phytoplankton bloom spanning 1 million km2 is consistently observed in the western Indian Subantarctic Zone. This oceanic region between the Subtropical and Subantarctic fronts in the Indian sector of the Southern Ocean contributes 20–40% of Southern Ocean carbon export to the deep ocean. However, aeolian inputs of iron, the key limiting nutrient for primary production, support only half of the phytoplanktonic iron demand of this bloom. Here we show that primary production in the western Indian Subantarctic Zone is sustained by long-range transport of iron via the Agulhas Current, one of the strongest ocean currents, which flows southwestward along the southern African coast. Float trajectories and high-resolution model diagnostics indicate that these waters, enriched with iron over the African margin, cross the Subtropical Front via the region’s intense mesoscale eddy variability. Removing the African sedimentary iron source in the model decreases surface iron concentrations in the western Indian Subantarctic Zone by 55%, reducing annual primary production and carbon export by 25% and 26%, respectively. Strengthening of the Agulhas Return Current over the past 130 kyr may therefore have increased iron supply and palaeoproductivity in the Indian Subantarctic Zone, potentially leading to enhanced atmospheric CO2 drawdown. Recurrent phytoplankton blooms in the western Indian Subantarctic Zone are largely supported by iron-rich water transported into the region by the Agulhas Current, according to an analysis of float data and regional ocean modelling.
{"title":"Western Indian subantarctic phytoplankton blooms fertilized by iron-enriched Agulhas water","authors":"Eva Bucciarelli, Pierrick Penven, Stéphane Pous, Alessandro Tagliabue","doi":"10.1038/s41561-025-01823-z","DOIUrl":"10.1038/s41561-025-01823-z","url":null,"abstract":"A phytoplankton bloom spanning 1 million km2 is consistently observed in the western Indian Subantarctic Zone. This oceanic region between the Subtropical and Subantarctic fronts in the Indian sector of the Southern Ocean contributes 20–40% of Southern Ocean carbon export to the deep ocean. However, aeolian inputs of iron, the key limiting nutrient for primary production, support only half of the phytoplanktonic iron demand of this bloom. Here we show that primary production in the western Indian Subantarctic Zone is sustained by long-range transport of iron via the Agulhas Current, one of the strongest ocean currents, which flows southwestward along the southern African coast. Float trajectories and high-resolution model diagnostics indicate that these waters, enriched with iron over the African margin, cross the Subtropical Front via the region’s intense mesoscale eddy variability. Removing the African sedimentary iron source in the model decreases surface iron concentrations in the western Indian Subantarctic Zone by 55%, reducing annual primary production and carbon export by 25% and 26%, respectively. Strengthening of the Agulhas Return Current over the past 130 kyr may therefore have increased iron supply and palaeoproductivity in the Indian Subantarctic Zone, potentially leading to enhanced atmospheric CO2 drawdown. Recurrent phytoplankton blooms in the western Indian Subantarctic Zone are largely supported by iron-rich water transported into the region by the Agulhas Current, according to an analysis of float data and regional ocean modelling.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 11","pages":"1152-1158"},"PeriodicalIF":16.1,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145382432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-10-21DOI: 10.1038/s41561-025-01822-0
Gina E. Moseley, Gabriella Koltai, Jonathan L. Baker, Jian Wang, Heather Stoll, Anika Donner, Lena Friedrich, Christoph Spötl, M. Paul Smith, Denis Scholz, Hai Cheng, Adam Hartland, Clivia Hejny, R. Lawrence Edwards
The sensitivity of terrestrial Arctic climate during the Late Miocene remains poorly understood, despite this interval marking the transition towards a cooler, more variable global climate and the prelude to Northern Hemisphere glaciation. Here we present a Late Miocene terrestrial proxy record, developed through the analysis of speleothems, from eastern North Greenland (Kalaallit Nunaat). Growth periods indicate multiple episodes of permafrost absence between ~10 and 5 Ma, suggesting mean annual air temperatures ~14 °C higher than present coinciding with atmospheric CO2 concentrations above ~310 ppm and local sea surface temperature anomalies >2 °C higher than present. Such moderate thresholds for permafrost absence highlight the climate sensitivity of North Greenland. Spikes in siliciclastic-derived trace elements ~6.3 and ~5.6 Ma are interpreted as terrestrial indicators for Late Miocene ephemeral glaciers in North Greenland. Climate variability recorded during speleothem growth periods was predominantly forced by obliquity, although, in the earliest Late Miocene, obliquity-scale anti-phasing with Antarctica may have occurred. Regional sea-ice extent was at its greatest following ~5.6 Ma during phases of transient glacial–interglacial cycles. Our findings highlight the sensitivity of the Arctic climate system and permafrost to modest CO2 levels and provide insights into regional responses to orbital forcing. The Late Miocene terrestrial climate in eastern North Greenland displayed elevated temperatures at moderate atmospheric CO2 levels and was highly variable, reflecting the shifting orbital and ocean circulation forcings in the Arctic as the world cooled, according to proxy records from speleothems.
{"title":"Late Miocene Arctic warmth and terrestrial climate recorded by North Greenland speleothems","authors":"Gina E. Moseley, Gabriella Koltai, Jonathan L. Baker, Jian Wang, Heather Stoll, Anika Donner, Lena Friedrich, Christoph Spötl, M. Paul Smith, Denis Scholz, Hai Cheng, Adam Hartland, Clivia Hejny, R. Lawrence Edwards","doi":"10.1038/s41561-025-01822-0","DOIUrl":"10.1038/s41561-025-01822-0","url":null,"abstract":"The sensitivity of terrestrial Arctic climate during the Late Miocene remains poorly understood, despite this interval marking the transition towards a cooler, more variable global climate and the prelude to Northern Hemisphere glaciation. Here we present a Late Miocene terrestrial proxy record, developed through the analysis of speleothems, from eastern North Greenland (Kalaallit Nunaat). Growth periods indicate multiple episodes of permafrost absence between ~10 and 5 Ma, suggesting mean annual air temperatures ~14 °C higher than present coinciding with atmospheric CO2 concentrations above ~310 ppm and local sea surface temperature anomalies >2 °C higher than present. Such moderate thresholds for permafrost absence highlight the climate sensitivity of North Greenland. Spikes in siliciclastic-derived trace elements ~6.3 and ~5.6 Ma are interpreted as terrestrial indicators for Late Miocene ephemeral glaciers in North Greenland. Climate variability recorded during speleothem growth periods was predominantly forced by obliquity, although, in the earliest Late Miocene, obliquity-scale anti-phasing with Antarctica may have occurred. Regional sea-ice extent was at its greatest following ~5.6 Ma during phases of transient glacial–interglacial cycles. Our findings highlight the sensitivity of the Arctic climate system and permafrost to modest CO2 levels and provide insights into regional responses to orbital forcing. The Late Miocene terrestrial climate in eastern North Greenland displayed elevated temperatures at moderate atmospheric CO2 levels and was highly variable, reflecting the shifting orbital and ocean circulation forcings in the Arctic as the world cooled, according to proxy records from speleothems.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 12","pages":"1252-1258"},"PeriodicalIF":16.1,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01822-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145699210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-21DOI: 10.1038/s41561-025-01774-5
Yan-Ning Kuo, Flavio Lehner, Isla R. Simpson, Clara Deser, Adam S. Phillips, Matthew Newman, Sang-Ik Shin, Spencer Wong, Julie M. Arblaster
{"title":"Publisher Correction: Recent southwestern US drought exacerbated by anthropogenic aerosols and tropical ocean warming","authors":"Yan-Ning Kuo, Flavio Lehner, Isla R. Simpson, Clara Deser, Adam S. Phillips, Matthew Newman, Sang-Ik Shin, Spencer Wong, Julie M. Arblaster","doi":"10.1038/s41561-025-01774-5","DOIUrl":"10.1038/s41561-025-01774-5","url":null,"abstract":"","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"18 11","pages":"1180-1180"},"PeriodicalIF":16.1,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01774-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145456856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1038/s41561-025-01811-3
Da Wang, Nicole X. Nie, Bradley J. Peters, James M. D. Day, Steven B. Shirey, Richard W. Carlson
Earth’s bulk composition has elemental and isotopic characteristics that cannot be fully reconciled with a mixture of known primitive meteorite compositions1–3. One potential explanation for this is that the proto-Earth accreted materials with isotopic signatures distinct from those accreted after the Moon-forming giant impact. Here we report high-precision mass-independent potassium isotopic measurements from thermal ionization mass spectrometry of terrestrial rocks from various ancient and modern sources in the crust and mantle that we argue are consistent with this explanation. Specifically, we found that some mafic Archaean rocks derived from the Hadean–Eoarchaean mantle (including samples from Isua, Nuvvuagittuq and the Kaapvaal Craton) and certain modern ocean island basalts (from La Réunion Island and Kama’ehuakanaloa volcano, Hawaii) exhibit an average 40K deficit of 65 parts per million compared to all other terrestrial samples analysed. The deficit distinguishes these samples from the bulk silicate Earth and any known meteorite group and cannot result from magmatic processes. Therefore, we propose this 40K deficit represents primitive proto-Earth mantle domains that largely escaped mantle mixing after the giant impact and exist in the present-day deep mantle, contributing to some modern hotspot volcanism. Some mafic rocks have a ⁴⁰K/³⁹K ratio lower than all other terrestrial samples, according to isotopic composition analyses, suggesting parts of Earth’s mantle have retained their composition prior to the Moon-forming impact to the present day.
地球的整体组成具有元素和同位素特征，这些特征不能与已知的原始陨石组成的混合物完全一致1 - 3。一种可能的解释是，原地球吸积的物质具有同位素特征，与月球形成大碰撞后吸积的物质不同。在这里，我们报告了来自地壳和地幔中各种古代和现代来源的陆相岩石的热电离质谱的高精度质量无关的钾同位素测量，我们认为这与这种解释是一致的。具体来说，我们发现，与所有其他陆地样本相比，来自于海底宙-太古宙地幔的一些基性太古宙岩石（包括来自Isua， Nuvvuagittuq和Kaapvaal克拉通的样本）和某些现代海洋岛屿玄武岩（来自夏威夷的La r union岛和Kama 'ehuakanaloa火山）的平均40K缺陷为百万分之65。这种缺陷将这些样品与大块硅酸盐地球和任何已知的陨石群区分开来，并且不可能是岩浆作用的结果。因此，我们认为这40K赤字代表了原始的原地球地幔域，这些域在大碰撞后基本上逃脱了地幔混合，存在于今天的深部地幔中，对现代热点火山活动有贡献。根据同位素组成分析，一些基性岩石的⁴⁰K/³⁹K比低于所有其他陆地样本，这表明部分地幔在月球形成之前一直保持着它们的组成直到今天。
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