Pub Date : 2026-01-13DOI: 10.1038/s41561-025-01896-w
Ruliang He, Alexandre Pohl, Xingliang Zhang, Chao Chang, Ashley Prow-Fleischer, Jonathan L. Payne, Shuhai Xiao, Andy Ridgwell, Zunli Lu
Major changes in the oxygenation of the atmosphere and ocean have been suggested to trigger the taxonomic diversification and ecological expansion of complex life, including animals, during the Neoproterozoic–Palaeozoic transition. However, testing this hypothesis is hampered by the paucity of quantitative constraints on the oceanic oxygen availability at that time. Here we show how the spatial pattern of I/Ca ratios in marine carbonates—a proxy for dissolved oxygen in the local upper ocean—provides a fingerprint of the oxygenation state of Earth’s surface. Spatial analyses on published I/Ca ratios spanning the past 2,000 million years show that the latitudinal gradient of oxygen concentrations in the upper ocean was reversed in the Proterozoic eon relative to the modern pattern of decreasing oxygen concentrations from the mid-latitudes to the Equator. Using an Earth system model, we identify that the Proterozoic I/Ca latitudinal pattern is associated with a biosphere-controlled distribution of oxygen in the upper ocean at a low atmospheric oxygen level, and the transition to a modern pattern in the I/Ca proxy may correspond to a threshold of around 1% of today’s atmospheric oxygen concentration.
{"title":"A reversed latitudinal ocean oxygen gradient in the Proterozoic Eon","authors":"Ruliang He, Alexandre Pohl, Xingliang Zhang, Chao Chang, Ashley Prow-Fleischer, Jonathan L. Payne, Shuhai Xiao, Andy Ridgwell, Zunli Lu","doi":"10.1038/s41561-025-01896-w","DOIUrl":"https://doi.org/10.1038/s41561-025-01896-w","url":null,"abstract":"Major changes in the oxygenation of the atmosphere and ocean have been suggested to trigger the taxonomic diversification and ecological expansion of complex life, including animals, during the Neoproterozoic–Palaeozoic transition. However, testing this hypothesis is hampered by the paucity of quantitative constraints on the oceanic oxygen availability at that time. Here we show how the spatial pattern of I/Ca ratios in marine carbonates—a proxy for dissolved oxygen in the local upper ocean—provides a fingerprint of the oxygenation state of Earth’s surface. Spatial analyses on published I/Ca ratios spanning the past 2,000 million years show that the latitudinal gradient of oxygen concentrations in the upper ocean was reversed in the Proterozoic eon relative to the modern pattern of decreasing oxygen concentrations from the mid-latitudes to the Equator. Using an Earth system model, we identify that the Proterozoic I/Ca latitudinal pattern is associated with a biosphere-controlled distribution of oxygen in the upper ocean at a low atmospheric oxygen level, and the transition to a modern pattern in the I/Ca proxy may correspond to a threshold of around 1% of today’s atmospheric oxygen concentration.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"4 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956345","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 : 2026-01-13DOI: 10.1038/s41561-025-01899-7
Adrià Descals, Ivan A. Janssens, Josep Peñuelas
Emissions from deforestation and savannah fires can travel over long distances and contribute to nutrient deposition in intact tropical forests, where phosphorus limits productivity. The magnitude of this deposition and its influence on the carbon sink, however, remain uncertain. Here we used satellite- and model-based geospatial datasets with feature importance analysis to quantify the influence of fire-derived nutrient inputs on Amazon rainforest productivity. Atmospheric transport modelling indicated that plumes originating in the southern arc of deforestation deliver aerosols into the Amazon basin, creating a south-to-northeast gradient in phosphorus deposition across the Amazon rainforest. This gradient in phosphorus deposition aligned with spatial patterns in sun-induced fluorescence, a proxy for gross primary productivity. We show that long-term phosphorus deposition was the strongest predictor of gross primary productivity, accounting for 22.5% of total spatial variability, and was linked to gains of 7.4 gC m−2 yr−1 per 1 mg P m−2 yr−1 deposited. Our results demonstrate that fire-derived deposition can alleviate chronic nutrient limitations in undisturbed tropical forests and influence spatial patterns of productivity. This nutrient fertilization partially offsets carbon losses from deforestation and fires, with important implications for global carbon budgets.
森林砍伐和草原火灾产生的排放物可以传播很长一段距离，并在完整的热带森林中造成营养沉积，而磷限制了热带森林的生产力。然而，这种沉积的规模及其对碳汇的影响仍不确定。在这里，我们使用基于卫星和模型的地理空间数据集以及特征重要性分析来量化火源养分输入对亚马逊雨林生产力的影响。大气运输模型表明，源自南部毁林弧线的羽流将气溶胶输送到亚马逊盆地，在亚马逊雨林中形成了从南到东北的磷沉积梯度。磷沉积的这种梯度与太阳诱导荧光的空间模式一致，这是总初级生产力的代表。研究表明，长期磷沉积是总初级生产力的最强预测因子，占总空间变异的22.5%，并且与每1 mg P m−2 yr−1沉积7.4 gC m−2 yr−1有关。研究结果表明，火源沉积可以缓解未受干扰热带森林的慢性营养限制，并影响生产力的空间格局。这种养分施肥部分抵消了森林砍伐和火灾造成的碳损失，对全球碳预算具有重要意义。
{"title":"Amazon forest nutrient limitation is mitigated by distant fire emissions","authors":"Adrià Descals, Ivan A. Janssens, Josep Peñuelas","doi":"10.1038/s41561-025-01899-7","DOIUrl":"https://doi.org/10.1038/s41561-025-01899-7","url":null,"abstract":"Emissions from deforestation and savannah fires can travel over long distances and contribute to nutrient deposition in intact tropical forests, where phosphorus limits productivity. The magnitude of this deposition and its influence on the carbon sink, however, remain uncertain. Here we used satellite- and model-based geospatial datasets with feature importance analysis to quantify the influence of fire-derived nutrient inputs on Amazon rainforest productivity. Atmospheric transport modelling indicated that plumes originating in the southern arc of deforestation deliver aerosols into the Amazon basin, creating a south-to-northeast gradient in phosphorus deposition across the Amazon rainforest. This gradient in phosphorus deposition aligned with spatial patterns in sun-induced fluorescence, a proxy for gross primary productivity. We show that long-term phosphorus deposition was the strongest predictor of gross primary productivity, accounting for 22.5% of total spatial variability, and was linked to gains of 7.4 gC m−2 yr−1 per 1 mg P m−2 yr−1 deposited. Our results demonstrate that fire-derived deposition can alleviate chronic nutrient limitations in undisturbed tropical forests and influence spatial patterns of productivity. This nutrient fertilization partially offsets carbon losses from deforestation and fires, with important implications for global carbon budgets.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"10 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956344","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 : 2026-01-12DOI: 10.1038/s41561-025-01904-z
Extreme weather and climate-related disasters are escalating in severity, frequency, and impact. Global climate policy must embed formal mechanisms that attribute these events and their consequences to major carbon emitters, ensuring accountability and accelerating the implementation of effective mitigation strategies.
{"title":"Extreme weather event accountability","authors":"","doi":"10.1038/s41561-025-01904-z","DOIUrl":"10.1038/s41561-025-01904-z","url":null,"abstract":"Extreme weather and climate-related disasters are escalating in severity, frequency, and impact. Global climate policy must embed formal mechanisms that attribute these events and their consequences to major carbon emitters, ensuring accountability and accelerating the implementation of effective mitigation strategies.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 1","pages":"1-1"},"PeriodicalIF":16.1,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01904-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145950806","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 : 2026-01-09DOI: 10.1038/s41561-025-01894-y
Jialing Li, Gengke Lai, Lin Meng, Constantin M. Zohner, Josep Peñuelas, Sander Veraverbeke, Jan Hjort, Philippe Ciais, Yang Chen, Xin Li, Chaoyang Wu
{"title":"Amplified Arctic–boreal fire regimes from permafrost thaw feedbacks","authors":"Jialing Li, Gengke Lai, Lin Meng, Constantin M. Zohner, Josep Peñuelas, Sander Veraverbeke, Jan Hjort, Philippe Ciais, Yang Chen, Xin Li, Chaoyang Wu","doi":"10.1038/s41561-025-01894-y","DOIUrl":"https://doi.org/10.1038/s41561-025-01894-y","url":null,"abstract":"","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"25 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938250","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 : 2026-01-09DOI: 10.1038/s41561-025-01897-9
Yongqiang Zhang, Günter Blöschl, Haoshan Wei, Dongdong Kong, Ning Ma, Thorsten Wagener, Jing Tian, Jun Xia, Congcong Li, Longhao Wang, Francis H. S. Chiew, L. Ruby Leung, Xingcai Liu, Hongxing Zheng, Xuanze Zhang, Changming Liu
{"title":"Overestimation of past and future increases in global river flow by Earth system models","authors":"Yongqiang Zhang, Günter Blöschl, Haoshan Wei, Dongdong Kong, Ning Ma, Thorsten Wagener, Jing Tian, Jun Xia, Congcong Li, Longhao Wang, Francis H. S. Chiew, L. Ruby Leung, Xingcai Liu, Hongxing Zheng, Xuanze Zhang, Changming Liu","doi":"10.1038/s41561-025-01897-9","DOIUrl":"https://doi.org/10.1038/s41561-025-01897-9","url":null,"abstract":"","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"47 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938307","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 : 2026-01-08DOI: 10.1038/s41561-025-01900-3
Global drifter data reveal that tropical cyclone-induced sea surface cooling in storm-affected areas is far weaker than indicated by estimates from microwave satellites and state-of-the-art climate models. Despite enhanced self-induced cooling driven by greenhouse warming, tropical cyclones are fuelled by a sea surface warming trend that is about twice the tropical mean warming.
{"title":"Cyclone-induced cooling is weaker than suggested by previous estimates","authors":"","doi":"10.1038/s41561-025-01900-3","DOIUrl":"10.1038/s41561-025-01900-3","url":null,"abstract":"Global drifter data reveal that tropical cyclone-induced sea surface cooling in storm-affected areas is far weaker than indicated by estimates from microwave satellites and state-of-the-art climate models. Despite enhanced self-induced cooling driven by greenhouse warming, tropical cyclones are fuelled by a sea surface warming trend that is about twice the tropical mean warming.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 2","pages":"133-134"},"PeriodicalIF":16.1,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145937554","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 : 2026-01-08DOI: 10.1038/s41561-025-01888-w
Pauline Le Coq, Urania Christaki, France Van Wambeke, Elisabeth Chevillon, Bruno Zakardjian, Marc Garel, Sophie Guasco, Chloé M. J. Baumas, Anne E. Dekas, Patricia Bonin, Badr Al Ali, Maéva Gesson, Frédéric Le Moigne, Mireille Pujo-Pay, Olivier Crispi, Olivier Grosso, Thierry Moutin, Nagib Bhairy, Emmanuel de Saint Léger, Laurent Memery, Lionel Guidi, Fabrice Armougom, Hans-Peter Grossart, Christian Tamburini
The mesopelagic zone, between 100 m and 1,000 m depth, is a crucial layer in which carbon preliminary coming down from the surface is transformed before a portion makes it into the deep ocean. While eddies and their fronts influence surface productivity and carbon export, their effects deeper in the water column remain poorly understood. Here we show the importance and contribution of dark carbon fixation—the conversion of inorganic into organic carbon by prokaryotes—across five contrasting hydrological features in the North Atlantic, using isotopic tracers and quantification of chemoautotrophy genes. The approach allows simultaneous assessment of dark carbon fixation and heterotrophic activity of prokaryotes living suspended in seawater and attached to gravitationally settling particles. Our results highlight that heterotrophic prokaryotes attached to sinking particles contribute up to 21% of the total organic carbon required to sustain prokaryotic metabolism under the influence of eddy fronts. By contrast, dark carbon fixation by suspended prokaryotes can contribute up to half of the total carbon input to the mesopelagic zone in the cyclonic eddy. Our findings challenge the idea that carbon cycling in the mid-depth ocean is uniform and highlight the need to integrate microbial fractions and physical heterogeneity into ocean carbon models. Genetic and isotopic analyses of samples from the northeast Atlantic reveal that suspended prokaryotic dark carbon fixation substantially fuels carbon inputs below the sunlit ocean, while particle-attached communities make an overlooked contribution to carbon demand.
{"title":"Distinct contributions of suspended and sinking prokaryotes to mesopelagic carbon budget","authors":"Pauline Le Coq, Urania Christaki, France Van Wambeke, Elisabeth Chevillon, Bruno Zakardjian, Marc Garel, Sophie Guasco, Chloé M. J. Baumas, Anne E. Dekas, Patricia Bonin, Badr Al Ali, Maéva Gesson, Frédéric Le Moigne, Mireille Pujo-Pay, Olivier Crispi, Olivier Grosso, Thierry Moutin, Nagib Bhairy, Emmanuel de Saint Léger, Laurent Memery, Lionel Guidi, Fabrice Armougom, Hans-Peter Grossart, Christian Tamburini","doi":"10.1038/s41561-025-01888-w","DOIUrl":"10.1038/s41561-025-01888-w","url":null,"abstract":"The mesopelagic zone, between 100 m and 1,000 m depth, is a crucial layer in which carbon preliminary coming down from the surface is transformed before a portion makes it into the deep ocean. While eddies and their fronts influence surface productivity and carbon export, their effects deeper in the water column remain poorly understood. Here we show the importance and contribution of dark carbon fixation—the conversion of inorganic into organic carbon by prokaryotes—across five contrasting hydrological features in the North Atlantic, using isotopic tracers and quantification of chemoautotrophy genes. The approach allows simultaneous assessment of dark carbon fixation and heterotrophic activity of prokaryotes living suspended in seawater and attached to gravitationally settling particles. Our results highlight that heterotrophic prokaryotes attached to sinking particles contribute up to 21% of the total organic carbon required to sustain prokaryotic metabolism under the influence of eddy fronts. By contrast, dark carbon fixation by suspended prokaryotes can contribute up to half of the total carbon input to the mesopelagic zone in the cyclonic eddy. Our findings challenge the idea that carbon cycling in the mid-depth ocean is uniform and highlight the need to integrate microbial fractions and physical heterogeneity into ocean carbon models. Genetic and isotopic analyses of samples from the northeast Atlantic reveal that suspended prokaryotic dark carbon fixation substantially fuels carbon inputs below the sunlit ocean, while particle-attached communities make an overlooked contribution to carbon demand.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 2","pages":"165-172"},"PeriodicalIF":16.1,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145919995","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 : 2026-01-08DOI: 10.1038/s41561-025-01879-x
Shoude Guan, Mengya Huang, Wenju Cai, Zhengguang Zhang, I-I Lin, Hyun-Sook Kim, Lei Zhou, Xiaopei Lin, Zhao Xu, Fei-Fei Jin, Wei Mei, Qian Wang, Chun Zhou, Ze Meng, Jiwei Tian, Wei Zhao
Sea surface temperature directly beneath tropical cyclones is crucial for their intensification. In the long term, global warming heats the surface oceans, intensifying tropical cyclones, whereas concurrently with a cyclone, inner-core surface cooling is induced by the cyclone itself curtailing its intensification. However, the magnitude of cyclone-induced cooling, or the trend in storm-local sea surface temperature, remains uncertain. Here we provide a quantification using global surface drifter data from 1992 to 2021. We find that storm-local sea surface temperatures are rising at 0.29 ± 0.07 °C per decade—about twice the average rate in tropical cyclone-active regions despite enhanced cyclone-induced cooling; furthermore, the magnitude of cyclone-induced inner-core cooling is far smaller than previous estimates. The inner-core cooling measured by drifters is −0.68 ± 0.04 °C, substantially less than microwave satellite estimates (−1.05 ± 0.06 °C). State-of-the-art climate models tend to overestimate inner-core cooling while underestimating storm intensity. These findings offer observational benchmarks for models and suggest that current projections may underestimate the strength, frequency and impacts of major tropical cyclones. Tropical cyclones cool the ocean surface less than previously thought, indicating that current projections may underestimate their future intensity and frequency, according to an analysis of global sea surface drifters data over 1992–2021.
{"title":"Weak self-induced cooling of tropical cyclones amid fast sea surface warming","authors":"Shoude Guan, Mengya Huang, Wenju Cai, Zhengguang Zhang, I-I Lin, Hyun-Sook Kim, Lei Zhou, Xiaopei Lin, Zhao Xu, Fei-Fei Jin, Wei Mei, Qian Wang, Chun Zhou, Ze Meng, Jiwei Tian, Wei Zhao","doi":"10.1038/s41561-025-01879-x","DOIUrl":"10.1038/s41561-025-01879-x","url":null,"abstract":"Sea surface temperature directly beneath tropical cyclones is crucial for their intensification. In the long term, global warming heats the surface oceans, intensifying tropical cyclones, whereas concurrently with a cyclone, inner-core surface cooling is induced by the cyclone itself curtailing its intensification. However, the magnitude of cyclone-induced cooling, or the trend in storm-local sea surface temperature, remains uncertain. Here we provide a quantification using global surface drifter data from 1992 to 2021. We find that storm-local sea surface temperatures are rising at 0.29 ± 0.07 °C per decade—about twice the average rate in tropical cyclone-active regions despite enhanced cyclone-induced cooling; furthermore, the magnitude of cyclone-induced inner-core cooling is far smaller than previous estimates. The inner-core cooling measured by drifters is −0.68 ± 0.04 °C, substantially less than microwave satellite estimates (−1.05 ± 0.06 °C). State-of-the-art climate models tend to overestimate inner-core cooling while underestimating storm intensity. These findings offer observational benchmarks for models and suggest that current projections may underestimate the strength, frequency and impacts of major tropical cyclones. Tropical cyclones cool the ocean surface less than previously thought, indicating that current projections may underestimate their future intensity and frequency, according to an analysis of global sea surface drifters data over 1992–2021.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 2","pages":"153-158"},"PeriodicalIF":16.1,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01879-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145919994","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 : 2026-01-07DOI: 10.1038/s41561-025-01878-y
Flavia Boscolo-Galazzo, Victoria E. Taylor, Eirik V. Galaasen, Diederik Liebrand, Edward Gasson, Edoardo Dallanave, Alvaro Fernandez-Bremer, Jakub Witkowski, Steve M. Bohaty, A. Nele Meckler
Our understanding of the long-term behaviour of global climate and the Antarctic ice sheet relies heavily on the oxygen isotopic composition of marine calcite (δ18Ocalcite), which reflects a combination of ocean temperature and the amount of water stored in ice sheets. On the basis of δ18Ocalcite, the Antarctic ice sheet has been interpreted as extremely dynamic in the Oligocene, 34–23 million years ago. Yet, the proposed continental-scale ice volume changes are challenging to reproduce with models and may be overestimated owing to a larger influence of temperature on the deep-sea δ18Ocalcite than previously assumed. Here we present the first Oligocene record of orbital variability in deep ocean temperature based on benthic foraminiferal clumped isotope thermometry, a method affected only by temperature and independent of seawater chemistry. We find large, eccentricity-paced temperature variations of up to 4 °C, sufficient to explain the δ18Ocalcite cycles without requiring continental-scale ice volume changes. This finding is consistent with the simulated stability of the Antarctic ice sheet, highlighting the importance of robust independent temperature reconstructions. Our results show that the temperature in the deep Southern Ocean, and possibly globally, is highly sensitive to the seasonal distribution of insolation in an Oligocene-like climate state warmer than today. Large benthic oxygen isotope fluctuations in the Oligocene Southern Ocean primarily represent deep water temperature changes, suggesting the Antarctic ice sheet volume was relatively stable, according to a clumped isotope record.
{"title":"Oligocene deep ocean oxygen isotope variations primarily driven by temperature","authors":"Flavia Boscolo-Galazzo, Victoria E. Taylor, Eirik V. Galaasen, Diederik Liebrand, Edward Gasson, Edoardo Dallanave, Alvaro Fernandez-Bremer, Jakub Witkowski, Steve M. Bohaty, A. Nele Meckler","doi":"10.1038/s41561-025-01878-y","DOIUrl":"10.1038/s41561-025-01878-y","url":null,"abstract":"Our understanding of the long-term behaviour of global climate and the Antarctic ice sheet relies heavily on the oxygen isotopic composition of marine calcite (δ18Ocalcite), which reflects a combination of ocean temperature and the amount of water stored in ice sheets. On the basis of δ18Ocalcite, the Antarctic ice sheet has been interpreted as extremely dynamic in the Oligocene, 34–23 million years ago. Yet, the proposed continental-scale ice volume changes are challenging to reproduce with models and may be overestimated owing to a larger influence of temperature on the deep-sea δ18Ocalcite than previously assumed. Here we present the first Oligocene record of orbital variability in deep ocean temperature based on benthic foraminiferal clumped isotope thermometry, a method affected only by temperature and independent of seawater chemistry. We find large, eccentricity-paced temperature variations of up to 4 °C, sufficient to explain the δ18Ocalcite cycles without requiring continental-scale ice volume changes. This finding is consistent with the simulated stability of the Antarctic ice sheet, highlighting the importance of robust independent temperature reconstructions. Our results show that the temperature in the deep Southern Ocean, and possibly globally, is highly sensitive to the seasonal distribution of insolation in an Oligocene-like climate state warmer than today. Large benthic oxygen isotope fluctuations in the Oligocene Southern Ocean primarily represent deep water temperature changes, suggesting the Antarctic ice sheet volume was relatively stable, according to a clumped isotope record.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 2","pages":"209-215"},"PeriodicalIF":16.1,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01878-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145908118","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}
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