Pub Date : 2026-02-02DOI: 10.1038/s41561-025-01913-y
Marion Fourquez
Erosion by the West Antarctic Ice Sheet can supply iron to the Southern Ocean, with iron solubility as important as iron quantity in shaping ocean productivity and carbon cycling. The future projection of ocean carbon dynamics will therefore require integration of ice-sheet processes into ocean biogeochemistry models.
{"title":"Dusting off the iron hypothesis","authors":"Marion Fourquez","doi":"10.1038/s41561-025-01913-y","DOIUrl":"10.1038/s41561-025-01913-y","url":null,"abstract":"Erosion by the West Antarctic Ice Sheet can supply iron to the Southern Ocean, with iron solubility as important as iron quantity in shaping ocean productivity and carbon cycling. The future projection of ocean carbon dynamics will therefore require integration of ice-sheet processes into ocean biogeochemistry models.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 2","pages":"130-131"},"PeriodicalIF":16.1,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115578","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 : 2026-02-02DOI: 10.1038/s41561-025-01914-x
Joseph B. Novak, Alexander A. Prokopenko, Pavel E. Tarasov, James M. Russell, Emma R. Lindemuth, Koji Shichi, Kenji Kashiwaya, John Peck, Richard S. Vachula, George E. A. Swann, Pratigya J. Polissar
Earth system feedbacks can amplify greenhouse gas forcing but are difficult to quantify, particularly on land where long palaeoclimate records are scarce. Here we reconstructed warm-season temperatures and vegetation at Lake Baikal, Russia, over the past 8.6 million years. We document gradual late Neogene cooling that was punctuated by an abrupt transition approximately 2.7 million years ago to severe cold temperatures during glacial periods. Forests were replaced by open steppe–tundra ecosystems and permafrost probably extended into South Siberia during these Early Pleistocene cold intervals. Compiled palaeobotanical data suggest this ecosystem turnover occurred throughout the Arctic and subarctic, although the timescale of these changes is less understood. Reconstructed Early Pleistocene glacial temperatures and vegetation resemble Late Pleistocene glacial periods at Lake Baikal, despite much warmer mean global temperatures in the Early Pleistocene. These geologic observations support the view that regional climate can respond nonlinearly to global forcing. We hypothesize that both vegetation albedo and permafrost carbon storage may have played a key role in amplifying glacial–interglacial climate cycles through the last 2.7 million years alongside ocean and ice sheet feedbacks.
{"title":"Early Pleistocene ecosystem turnover in South Siberia linked to abrupt regional cooling","authors":"Joseph B. Novak, Alexander A. Prokopenko, Pavel E. Tarasov, James M. Russell, Emma R. Lindemuth, Koji Shichi, Kenji Kashiwaya, John Peck, Richard S. Vachula, George E. A. Swann, Pratigya J. Polissar","doi":"10.1038/s41561-025-01914-x","DOIUrl":"https://doi.org/10.1038/s41561-025-01914-x","url":null,"abstract":"Earth system feedbacks can amplify greenhouse gas forcing but are difficult to quantify, particularly on land where long palaeoclimate records are scarce. Here we reconstructed warm-season temperatures and vegetation at Lake Baikal, Russia, over the past 8.6 million years. We document gradual late Neogene cooling that was punctuated by an abrupt transition approximately 2.7 million years ago to severe cold temperatures during glacial periods. Forests were replaced by open steppe–tundra ecosystems and permafrost probably extended into South Siberia during these Early Pleistocene cold intervals. Compiled palaeobotanical data suggest this ecosystem turnover occurred throughout the Arctic and subarctic, although the timescale of these changes is less understood. Reconstructed Early Pleistocene glacial temperatures and vegetation resemble Late Pleistocene glacial periods at Lake Baikal, despite much warmer mean global temperatures in the Early Pleistocene. These geologic observations support the view that regional climate can respond nonlinearly to global forcing. We hypothesize that both vegetation albedo and permafrost carbon storage may have played a key role in amplifying glacial–interglacial climate cycles through the last 2.7 million years alongside ocean and ice sheet feedbacks.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"290 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102143","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 : 2026-01-29DOI: 10.1038/s41561-025-01901-2
Shuzhuang Wu, Alain Mazaud, Elisabeth Michel, Michael P. Erb, Thomas F. Stocker, Helen Eri Amsler, Perig Le Tallec-Carado, Frank Lamy, Samuel L. Jaccard
The Antarctic Circumpolar Current (ACC) plays a central role in regulating the global ocean circulation, climate and Antarctic Ice Sheet dynamics. Yet the spatiotemporal variability of the ACC during the Pleistocene remains poorly constrained. Here we reconstruct ACC flow-speed variation using a meridional transect of sediment cores from the Indian sector of the Southern Ocean. Our results reveal zonally asymmetric changes in ACC strength across the Southern Ocean on orbital timescales over the past one million years; the ACC intensified in the South Indian Ocean but weakened in the South Pacific during glacial and low-obliquity periods, with the opposite pattern during interglacial and high-obliquity periods. These anti-phased changes probably reflect an integrated response to bathymetric constraints, shifts in the Southern Hemisphere westerlies, sea-ice extent, buoyancy forcing and current confluence. Such zonally asymmetric and anti-phased ACC dynamics persisted during warmer-than-present intervals of the Pleistocene, offering a potential analogue for future anthropogenic warming—albeit under fundamentally different boundary conditions. Anti-phased changes in Antarctic Circumpolar Current strength between the Indian and Pacific sectors of the Southern Ocean occurred on orbital timescales over the past one million years, linked to glacial cycles and obliquity forcing, according to proxy records and modelling.
{"title":"Zonally asymmetric changes in the Antarctic Circumpolar Current strength over the past million years","authors":"Shuzhuang Wu, Alain Mazaud, Elisabeth Michel, Michael P. Erb, Thomas F. Stocker, Helen Eri Amsler, Perig Le Tallec-Carado, Frank Lamy, Samuel L. Jaccard","doi":"10.1038/s41561-025-01901-2","DOIUrl":"10.1038/s41561-025-01901-2","url":null,"abstract":"The Antarctic Circumpolar Current (ACC) plays a central role in regulating the global ocean circulation, climate and Antarctic Ice Sheet dynamics. Yet the spatiotemporal variability of the ACC during the Pleistocene remains poorly constrained. Here we reconstruct ACC flow-speed variation using a meridional transect of sediment cores from the Indian sector of the Southern Ocean. Our results reveal zonally asymmetric changes in ACC strength across the Southern Ocean on orbital timescales over the past one million years; the ACC intensified in the South Indian Ocean but weakened in the South Pacific during glacial and low-obliquity periods, with the opposite pattern during interglacial and high-obliquity periods. These anti-phased changes probably reflect an integrated response to bathymetric constraints, shifts in the Southern Hemisphere westerlies, sea-ice extent, buoyancy forcing and current confluence. Such zonally asymmetric and anti-phased ACC dynamics persisted during warmer-than-present intervals of the Pleistocene, offering a potential analogue for future anthropogenic warming—albeit under fundamentally different boundary conditions. Anti-phased changes in Antarctic Circumpolar Current strength between the Indian and Pacific sectors of the Southern Ocean occurred on orbital timescales over the past one million years, linked to glacial cycles and obliquity forcing, according to proxy records and modelling.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 2","pages":"201-208"},"PeriodicalIF":16.1,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01901-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089703","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 : 2026-01-28DOI: 10.1038/s41561-025-01908-9
Xuekun Fang, Qianna Du, Jens Mühle, Jianxin Hu, Ray F. Weiss, Ronald G. Prinn, Christina M. Harth, Simon O’Doherty, Dickon Young, Mengyue Ma, Xiaoyi Hu, Bowei Li, Siyuan Huang, Bo Yao
Hydrofluorocarbons (HFCs) with high global warming potential are regulated under the Kigali Amendment to the Montreal Protocol. While China began freezing production and consumption of HFCs in 2024, there are discrepancies among previous activity-based bottom-up emissions estimates and lack of observation-based inverse modelling emissions estimates of China’s HFC emissions since 2017. Here we use atmospheric observations across China and inverse modelling to reveal distinct emissions trends of nine HFCs from 2011 to 2021 in China. Our top-down emissions estimates reveal an overestimation of HFC emissions post-2017 by an average of 117.2 Tg CO2-equivalent per year, by China’s national official bottom-up emissions inventories. Also, we find that while eastern China is the largest emitter of HFCs in China (37.4% CO2-equivalent), non-eastern China contributed to national emissions (62.6%). Lastly, we show that non-Annex I countries (mostly developing countries under the UN climate framework) excluding China accounted for 61.3% of the global HFC emissions growth during 2011–2020, far surpassing contributions from Annex I countries (23.9%) and China (14.8%). These findings highlight the overlooked contributions of non-Annex I countries, excluding China, to global emissions growth.
{"title":"Estimation of hydrofluorocarbon emissions from China and other non-Annex I countries","authors":"Xuekun Fang, Qianna Du, Jens Mühle, Jianxin Hu, Ray F. Weiss, Ronald G. Prinn, Christina M. Harth, Simon O’Doherty, Dickon Young, Mengyue Ma, Xiaoyi Hu, Bowei Li, Siyuan Huang, Bo Yao","doi":"10.1038/s41561-025-01908-9","DOIUrl":"https://doi.org/10.1038/s41561-025-01908-9","url":null,"abstract":"Hydrofluorocarbons (HFCs) with high global warming potential are regulated under the Kigali Amendment to the Montreal Protocol. While China began freezing production and consumption of HFCs in 2024, there are discrepancies among previous activity-based bottom-up emissions estimates and lack of observation-based inverse modelling emissions estimates of China’s HFC emissions since 2017. Here we use atmospheric observations across China and inverse modelling to reveal distinct emissions trends of nine HFCs from 2011 to 2021 in China. Our top-down emissions estimates reveal an overestimation of HFC emissions post-2017 by an average of 117.2 Tg CO2-equivalent per year, by China’s national official bottom-up emissions inventories. Also, we find that while eastern China is the largest emitter of HFCs in China (37.4% CO2-equivalent), non-eastern China contributed to national emissions (62.6%). Lastly, we show that non-Annex I countries (mostly developing countries under the UN climate framework) excluding China accounted for 61.3% of the global HFC emissions growth during 2011–2020, far surpassing contributions from Annex I countries (23.9%) and China (14.8%). These findings highlight the overlooked contributions of non-Annex I countries, excluding China, to global emissions growth.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"273 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057189","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 : 2026-01-27DOI: 10.1038/s41561-025-01891-1
Quanjia Zhong, Johnny C. L. Chan, Wansuo Duan, Shifei Tu, Jianping Li, Jianping Gan, Ruiqiang Ding
Changes in the translation speed of landfalling tropical cyclones (TCs) pose great challenges in disaster preparedness. While some recent studies have discussed the increased chance of a reduction in the annual-mean translation speed of TCs after landfall, such changes before landfall have not been systematically investigated, especially for short-term variations (that is, hour-to-day timescales). Here we show, first based on observations, that globally, a TC about to make landfall tends to accelerate towards the coast, with an average acceleration of about 0.83 m s−1 per day, which means that the mean translation speed of a landfalling TC increases by ~48% during the 60-h period before landfall. Such an acceleration exists irrespective of TC intensity, seasonality and ocean basin, although its magnitude varies. Numerical simulations demonstrate that land–sea differences in surface roughness and thermal effect result in asymmetric circulation and convection in TCs, both of which are enhanced as the TC moves closer to the coast, leading to local changes in potential vorticity and thereby accelerating the storm. As this phenomenon is due to the land–sea contrast, a TC approaching the coast will probably have such an acceleration and hence it is inherent. Landfalling tropical cyclones generally accelerate as they approach coastlines due to changes in surface roughness and thermal properties, according to numerical modelling simulations and global observations.
热带气旋登陆平动速度的变化对灾害防范提出了巨大挑战。虽然最近的一些研究讨论了登陆后tc年平均转换速度降低的可能性增加，但尚未系统地调查登陆前的这种变化，特别是短期变化（即小时至日的时间尺度）。在这里，我们首先根据观测结果表明，全球范围内，即将登陆的TC倾向于加速向海岸移动，平均加速度约为0.83 m s - 1 /天，这意味着登陆TC的平均平移速度在登陆前60小时内增加了约48%。这种加速与TC强度、季节性和海洋盆地无关，但其幅度有所不同。数值模拟表明，海陆表面粗糙度和热效应的差异导致了TC内环流和对流的不对称，随着TC向海岸靠近，环流和对流的不对称增强，从而导致局地位涡度的变化，从而加速了风暴。由于这种现象是由于陆海对比，接近海岸的TC可能会有这样的加速度，因此它是固有的。
{"title":"Landfalling tropical cyclones accelerate due to land–sea thermal and roughness contrasts","authors":"Quanjia Zhong, Johnny C. L. Chan, Wansuo Duan, Shifei Tu, Jianping Li, Jianping Gan, Ruiqiang Ding","doi":"10.1038/s41561-025-01891-1","DOIUrl":"10.1038/s41561-025-01891-1","url":null,"abstract":"Changes in the translation speed of landfalling tropical cyclones (TCs) pose great challenges in disaster preparedness. While some recent studies have discussed the increased chance of a reduction in the annual-mean translation speed of TCs after landfall, such changes before landfall have not been systematically investigated, especially for short-term variations (that is, hour-to-day timescales). Here we show, first based on observations, that globally, a TC about to make landfall tends to accelerate towards the coast, with an average acceleration of about 0.83 m s−1 per day, which means that the mean translation speed of a landfalling TC increases by ~48% during the 60-h period before landfall. Such an acceleration exists irrespective of TC intensity, seasonality and ocean basin, although its magnitude varies. Numerical simulations demonstrate that land–sea differences in surface roughness and thermal effect result in asymmetric circulation and convection in TCs, both of which are enhanced as the TC moves closer to the coast, leading to local changes in potential vorticity and thereby accelerating the storm. As this phenomenon is due to the land–sea contrast, a TC approaching the coast will probably have such an acceleration and hence it is inherent. Landfalling tropical cyclones generally accelerate as they approach coastlines due to changes in surface roughness and thermal properties, according to numerical modelling simulations and global observations.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"19 2","pages":"159-164"},"PeriodicalIF":16.1,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41561-025-01891-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057192","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 : 2026-01-22DOI: 10.1038/s41561-025-01909-8
{"title":"Global water security is threatened by rising inequality","authors":"","doi":"10.1038/s41561-025-01909-8","DOIUrl":"https://doi.org/10.1038/s41561-025-01909-8","url":null,"abstract":"","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"271 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033651","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 : 2026-01-20DOI: 10.1038/s41561-025-01905-y
Jichuan Sheng, Qian Cheng, Hongqiang Yang
The global water-scarcity crisis is fundamentally driven by inequality, yet most forecasts overlook equity as a causal factor, leading to misdiagnosed problems and ineffective solutions. Here we develop a machine-learning-based global water-use forecasting model to project future water use and scarcity under distinct Shared Socioeconomic Pathways representing alternative development trajectories. Drawing on decades of historical data on human adaptation and resource use, the model predicts that by 2050, 6.5 billion people—equivalent to 65.5% of the global population—will face severe water scarcity under a high-challenge fragmentation scenario. By 2100, this figure is projected to rise to 8.0 billion, or 63% of the global population, far exceeding most previous estimates. Our analysis shows that a high inequality pathway directly amplifies water-scarcity risk. Critically, a technology-driven pathway improves aggregate water-use efficiency but concurrently deepens social and spatial inequalities. These findings underscore the need to move beyond purely technological fixes towards integrated, equitable water management, demonstrating that greater justice is inseparable from greater water security.
{"title":"Global water security threatened by rising inequality","authors":"Jichuan Sheng, Qian Cheng, Hongqiang Yang","doi":"10.1038/s41561-025-01905-y","DOIUrl":"https://doi.org/10.1038/s41561-025-01905-y","url":null,"abstract":"The global water-scarcity crisis is fundamentally driven by inequality, yet most forecasts overlook equity as a causal factor, leading to misdiagnosed problems and ineffective solutions. Here we develop a machine-learning-based global water-use forecasting model to project future water use and scarcity under distinct Shared Socioeconomic Pathways representing alternative development trajectories. Drawing on decades of historical data on human adaptation and resource use, the model predicts that by 2050, 6.5 billion people—equivalent to 65.5% of the global population—will face severe water scarcity under a high-challenge fragmentation scenario. By 2100, this figure is projected to rise to 8.0 billion, or 63% of the global population, far exceeding most previous estimates. Our analysis shows that a high inequality pathway directly amplifies water-scarcity risk. Critically, a technology-driven pathway improves aggregate water-use efficiency but concurrently deepens social and spatial inequalities. These findings underscore the need to move beyond purely technological fixes towards integrated, equitable water management, demonstrating that greater justice is inseparable from greater water security.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"64 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006100","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 : 2026-01-20DOI: 10.1038/s41561-025-01903-0
Julien Boucharel, Rafael Almar, Fei-Fei Jin, Sen Zhao, Malte F. Stuecker, Boris Dewitte
Extreme coastal flooding often arises when large-scale climate patterns and local ocean–atmosphere variability combine to magnify water levels beyond what communities can withstand. Understanding and anticipating these interactions is essential for protecting vulnerable coastlines. Here we aim to determine how two major modes of climate variability—the El Niño/Southern Oscillation and the North Atlantic Oscillation—individually and jointly influence extreme coastal water levels worldwide. Using global observational and reanalysis datasets spanning 1958–2023, we analyse their separate effects and diagnose potential nonlinear interactions through statistical and process-based methods. We show that specific, seasonally aligned phases of these two climate modes interact nonlinearly, producing coastal water levels far higher than expected from either mode alone. These combinations enhance storm activity and wave conditions from the eastern seaboard of North America to western Europe and the Mediterranean. We further show that incorporating these nonlinear interactions into a conceptual climate model enables skilful seasonal predictions of coastal flooding hazards several months in advance, demonstrating the feasibility of reliable early-warning systems for coastal risk reduction.
{"title":"Climate mode interactions amplify coastal flood risks and their seasonal predictability","authors":"Julien Boucharel, Rafael Almar, Fei-Fei Jin, Sen Zhao, Malte F. Stuecker, Boris Dewitte","doi":"10.1038/s41561-025-01903-0","DOIUrl":"https://doi.org/10.1038/s41561-025-01903-0","url":null,"abstract":"Extreme coastal flooding often arises when large-scale climate patterns and local ocean–atmosphere variability combine to magnify water levels beyond what communities can withstand. Understanding and anticipating these interactions is essential for protecting vulnerable coastlines. Here we aim to determine how two major modes of climate variability—the El Niño/Southern Oscillation and the North Atlantic Oscillation—individually and jointly influence extreme coastal water levels worldwide. Using global observational and reanalysis datasets spanning 1958–2023, we analyse their separate effects and diagnose potential nonlinear interactions through statistical and process-based methods. We show that specific, seasonally aligned phases of these two climate modes interact nonlinearly, producing coastal water levels far higher than expected from either mode alone. These combinations enhance storm activity and wave conditions from the eastern seaboard of North America to western Europe and the Mediterranean. We further show that incorporating these nonlinear interactions into a conceptual climate model enables skilful seasonal predictions of coastal flooding hazards several months in advance, demonstrating the feasibility of reliable early-warning systems for coastal risk reduction.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"50 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006099","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}
Near-Earth asteroids (NEAs) are small, airless bodies that orbit in near-Earth space. Recent studies suggest that their surface rocks can undergo crack growth and fragmentation through thermal fatigue induced by diurnal temperature cycling. This process may expose materials yet to be altered by solar wind irradiation and micrometeorite impacts, known as surface rejuvenation. However, the mechanism that generates the initial cracks required to trigger thermal fatigue fragmentation remains poorly understood despite its importance for understanding the geophysical evolution of asteroids. Here we use numerical approaches to show that stony, or S-complex NEAs, the most compositionally common group, can experience rapid temperature changes, or thermal shocks, sufficient to generate microcracks in surface rocks as they pass through the shadow of a terrestrial planet. Our statistical analysis of backward orbital integrations demonstrates that these asteroids pass through planetary shadows more often than they encounter planets closely enough for planetary tides to rejuvenate their surfaces. We also found that shadow passages are shorter than typical asteroid spin periods, indicating that expansion stress from rapid heating occurs immediately after contraction stress from rapid cooling. These results suggest that thermal shock caused by planetary shadows may help trigger the surface rejuvenation of stony NEAs.
{"title":"Surface rejuvenation of stony near-Earth asteroids triggered by planetary shadows","authors":"Kohei Kitazato, Sho Sakurai, Ryuki Hyodo, Naru Hirata","doi":"10.1038/s41561-025-01907-w","DOIUrl":"https://doi.org/10.1038/s41561-025-01907-w","url":null,"abstract":"Near-Earth asteroids (NEAs) are small, airless bodies that orbit in near-Earth space. Recent studies suggest that their surface rocks can undergo crack growth and fragmentation through thermal fatigue induced by diurnal temperature cycling. This process may expose materials yet to be altered by solar wind irradiation and micrometeorite impacts, known as surface rejuvenation. However, the mechanism that generates the initial cracks required to trigger thermal fatigue fragmentation remains poorly understood despite its importance for understanding the geophysical evolution of asteroids. Here we use numerical approaches to show that stony, or S-complex NEAs, the most compositionally common group, can experience rapid temperature changes, or thermal shocks, sufficient to generate microcracks in surface rocks as they pass through the shadow of a terrestrial planet. Our statistical analysis of backward orbital integrations demonstrates that these asteroids pass through planetary shadows more often than they encounter planets closely enough for planetary tides to rejuvenate their surfaces. We also found that shadow passages are shorter than typical asteroid spin periods, indicating that expansion stress from rapid heating occurs immediately after contraction stress from rapid cooling. These results suggest that thermal shock caused by planetary shadows may help trigger the surface rejuvenation of stony NEAs.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"21 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145968808","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 : 2026-01-14DOI: 10.1038/s41561-025-01898-8
Emily Black, Caroline Wainwright, Richard P. Allan, Pier Luigi Vidale
Climate change is intensifying drought risk, yet it is unclear which regions will be most vulnerable in the future. Here we investigate emerging hotspots of agricultural drought across the tropics and Northern Hemisphere extratropics using climate reanalysis and model simulations under a range of Shared Socioeconomic Pathways. Our analysis accounts for soil moisture at the onset of the growing season, as well as variability during the season itself, linking climate change to the land-surface water balance by classifying the dominant controls on evapotranspiration, including a newly defined state governed by plant extraction of water from the root zone. We show that much of Europe, southern Africa, northern South America and western North America are emerging hotspots of agricultural drought, with mechanisms of observed drying consistent with future projections. Drought trends are identified even where precipitation projections diverge. By focusing on growing seasons, our approach captures hotspots overlooked by annual metrics and shows that increasing drought frequency is compounded by shifts towards more severe and intense events. These findings have strong implications for food security and highlight the need for drought-resilient adaptation not only in the global south but also in extratropical regions where risk is already escalating.
{"title":"Emerging hotspots of agricultural drought under climate change","authors":"Emily Black, Caroline Wainwright, Richard P. Allan, Pier Luigi Vidale","doi":"10.1038/s41561-025-01898-8","DOIUrl":"https://doi.org/10.1038/s41561-025-01898-8","url":null,"abstract":"Climate change is intensifying drought risk, yet it is unclear which regions will be most vulnerable in the future. Here we investigate emerging hotspots of agricultural drought across the tropics and Northern Hemisphere extratropics using climate reanalysis and model simulations under a range of Shared Socioeconomic Pathways. Our analysis accounts for soil moisture at the onset of the growing season, as well as variability during the season itself, linking climate change to the land-surface water balance by classifying the dominant controls on evapotranspiration, including a newly defined state governed by plant extraction of water from the root zone. We show that much of Europe, southern Africa, northern South America and western North America are emerging hotspots of agricultural drought, with mechanisms of observed drying consistent with future projections. Drought trends are identified even where precipitation projections diverge. By focusing on growing seasons, our approach captures hotspots overlooked by annual metrics and shows that increasing drought frequency is compounded by shifts towards more severe and intense events. These findings have strong implications for food security and highlight the need for drought-resilient adaptation not only in the global south but also in extratropical regions where risk is already escalating.","PeriodicalId":19053,"journal":{"name":"Nature Geoscience","volume":"101 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145968824","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}
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