Pub Date : 2024-08-30DOI: 10.1088/1748-9326/ad6ea6
Amen Al-Yaari, Thomas Condom, Fabien Anthelme, Sophie Cauvy-Fraunié, Olivier Dangles, Clémentine Junquas, Pierre Moret, Antoine Rabatel
Climate change impacts on humans and ecosystems depend on the intensity, timing, and spatial variability of these changes. While considerable attention has been paid to current and future changes in temperature patterns, comparatively less attention has been devoted to water availability for humans and ecosystems. The aridity index (AI), the ratio of precipitation to potential evapotranspiration, is a common metric used to assess water availability within ecosystems. However, the role of snow in AI calculations within snowy eco-regions is often neglected, resulting in an incomplete understanding of water balance dynamics in these environments. In this study, we estimate aridification under ongoing climate change in Andean eco-regions (AEs), focusing on two horizons: 2050–2060 and 2090–2100. Using monthly TerraClimate data from 2013–2018, we calculated a mean AI for each AE, taking into account the absence of snow (pixels with a snow water equivalent (SWE) < 10 mm/month) and its presence (AI-snow; pixels with a SWE > 10 mm/month). We show that AI allows to differentiate the eco-regions, but that the incorporation of snow in the AI calculation highlights the heterogeneity of aridity conditions within some eco-regions with energy-limited regimes (AI > 1) in the snowy zones and water-limited regimes (AI < 1) elsewhere. Analysis of the CORDEX-SAM regional projections for the periods 2050–2060 and 2090–2100 indicates a general shift towards drier conditions prevailing over wetter conditions in most eco-regions, notably: the Southern Andean Steppe, the Central Andean Wet Puna, the Santa Marta Páramo, and the Peruvian Yungas. The projected reduction in snowfall in CORDEX-SAM, coupled with glacier volume loss, appears to be contributing to the prevalence of aridification across many AEs. These findings highlight potential transitions towards aridification in diverse eco-regions, with repercussions on water availability for humans and ecosystems.
{"title":"Warming-induced cryosphere changes predict drier Andean eco-regions","authors":"Amen Al-Yaari, Thomas Condom, Fabien Anthelme, Sophie Cauvy-Fraunié, Olivier Dangles, Clémentine Junquas, Pierre Moret, Antoine Rabatel","doi":"10.1088/1748-9326/ad6ea6","DOIUrl":"https://doi.org/10.1088/1748-9326/ad6ea6","url":null,"abstract":"Climate change impacts on humans and ecosystems depend on the intensity, timing, and spatial variability of these changes. While considerable attention has been paid to current and future changes in temperature patterns, comparatively less attention has been devoted to water availability for humans and ecosystems. The aridity index (AI), the ratio of precipitation to potential evapotranspiration, is a common metric used to assess water availability within ecosystems. However, the role of snow in AI calculations within snowy eco-regions is often neglected, resulting in an incomplete understanding of water balance dynamics in these environments. In this study, we estimate aridification under ongoing climate change in Andean eco-regions (AEs), focusing on two horizons: 2050–2060 and 2090–2100. Using monthly TerraClimate data from 2013–2018, we calculated a mean AI for each AE, taking into account the absence of snow (pixels with a snow water equivalent (SWE) < 10 mm/month) and its presence (AI-snow; pixels with a SWE > 10 mm/month). We show that AI allows to differentiate the eco-regions, but that the incorporation of snow in the AI calculation highlights the heterogeneity of aridity conditions within some eco-regions with energy-limited regimes (AI > 1) in the snowy zones and water-limited regimes (AI < 1) elsewhere. Analysis of the CORDEX-SAM regional projections for the periods 2050–2060 and 2090–2100 indicates a general shift towards drier conditions prevailing over wetter conditions in most eco-regions, notably: the Southern Andean Steppe, the Central Andean Wet Puna, the Santa Marta Páramo, and the Peruvian Yungas. The projected reduction in snowfall in CORDEX-SAM, coupled with glacier volume loss, appears to be contributing to the prevalence of aridification across many AEs. These findings highlight potential transitions towards aridification in diverse eco-regions, with repercussions on water availability for humans and ecosystems.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"275 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142213557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1088/1748-9326/ad715a
Armineh Barkhordarian
Changes in regional climate variability serve as the initial indicators of positive climate feedback mechanisms, which are expected to intensify as greenhouse gas (GHG) emissions unfold. Therefore, it is crucial to examine the extent to which GHG-induced changes in regional climate variability, in isolation from changes in mean climate, contribute to the frequency of extreme weather events. In this study, I build upon the concept of the fraction of attributable risk (FAR) by introducing the fraction of preventable risk (FPR), allowing for the assessment of GHG forcing’s contribution to risk reduction in scenarios of decreasing risk extremes. Results derived from four global climate models indicate that while the predominant factor amplifying the frequency of hot extremes is the mean warming, with a 18-fold increase in probability and an attributable risk fraction of 0.96 to GHG forcing, changes in regional climate variability have already modified the probability of extremes. In South Asia, for instance, the 12-fold increase in hot extremes resulting from mean warming is compounded by an additional ∼3 times, solely attributed to the increased temperature variability. Conversely, during winter in the Arctic, the 10-fold increase in the frequency of hot extremes due to mean warming is offset by a ∼2.5-fold decrease resulting from diminished variability, with a preventable risk fraction of −0.55 to GHG forcing. Concerning heavy-precipitation events, in certain regions, GHG-induced changes in precipitation variability carry greater significance than changes in the mean. For example, in the West African summer monsoon region GHG forcing is amplifying the risk of extreme monsoon precipitation by ∼4 times. This amplified risk of potential flooding arises from increases in both mean precipitation and variability. Separating attribution metrics into mean and variability components offers valuable insights into region-specific mechanisms affecting extreme event frequency.
{"title":"Attribution of extremes to greenhouse gas-induced changes in regional climate variability, distinct from changes in mean climate","authors":"Armineh Barkhordarian","doi":"10.1088/1748-9326/ad715a","DOIUrl":"https://doi.org/10.1088/1748-9326/ad715a","url":null,"abstract":"Changes in regional climate variability serve as the initial indicators of positive climate feedback mechanisms, which are expected to intensify as greenhouse gas (GHG) emissions unfold. Therefore, it is crucial to examine the extent to which GHG-induced changes in regional climate variability, in isolation from changes in mean climate, contribute to the frequency of extreme weather events. In this study, I build upon the concept of the fraction of attributable risk (FAR) by introducing the fraction of preventable risk (FPR), allowing for the assessment of GHG forcing’s contribution to risk reduction in scenarios of decreasing risk extremes. Results derived from four global climate models indicate that while the predominant factor amplifying the frequency of hot extremes is the mean warming, with a 18-fold increase in probability and an attributable risk fraction of 0.96 to GHG forcing, changes in regional climate variability have already modified the probability of extremes. In South Asia, for instance, the 12-fold increase in hot extremes resulting from mean warming is compounded by an additional ∼3 times, solely attributed to the increased temperature variability. Conversely, during winter in the Arctic, the 10-fold increase in the frequency of hot extremes due to mean warming is offset by a ∼2.5-fold decrease resulting from diminished variability, with a preventable risk fraction of −0.55 to GHG forcing. Concerning heavy-precipitation events, in certain regions, GHG-induced changes in precipitation variability carry greater significance than changes in the mean. For example, in the West African summer monsoon region GHG forcing is amplifying the risk of extreme monsoon precipitation by ∼4 times. This amplified risk of potential flooding arises from increases in both mean precipitation and variability. Separating attribution metrics into mean and variability components offers valuable insights into region-specific mechanisms affecting extreme event frequency.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"331 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142213579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1088/1748-9326/ad703f
Wentao Mi, Weibo Ren, Yuan Chi, Hao Zheng, Ellen Fry, Feng Yuan, Yaling Liu
Soil seed banks are the main seed reservoirs globally and are critical for the regeneration of grassland plant populations. Grazing often affects the density and diversity of grassland soil seed banks; however, it is not clear how these effects vary on a global scale with grazing intensity, grazing duration, and climatic conditions. Here, we screened 92 independent published articles and performed a meta-analysis of the extracted data. The effects of grazing on four soil seed bank density and diversity indices were analyzed. Four alpha diversity indices, namely Shannon–Wiener, Margalef, Pielou, and Simpson indices, were selected in this study. The Shannon–Wiener index reflects the species complexity of the community. The Margalef index reflects species richness of the seed bank. The Pielou index reflects whether the number of seeds of all species in the seed bank is evenly distributed, and the Simpson’s index reflects the status of dominant plants in the seed bank. We found that grazing significantly decreased the total density of soil seed banks. Perennial plant seed banks were more affected by grazing than annual plant seed banks. Heavy grazing significantly decreased the Margalef index of seed banks, while moderate grazing significantly decreased the Simpson’s alpha diversity index. Long-term grazing (>10 years) had the greatest impact on Simpson’s alpha diversity index, while medium-term grazing (5–10 years) had a significant negative impact on Shannon–Wiener, Margalef, and Pielou indices. In addition, our results show that grazing has a greater effect on seed banks in arid areas than those in temperate areas. Knowledge of climate-specific effects will contribute to understanding the risk of local extinctions in grassland populations and help decision-makers maintain the health of grassland ecosystems.
{"title":"Heavy grazing reduces the potential for grassland restoration: a global meta-analysis","authors":"Wentao Mi, Weibo Ren, Yuan Chi, Hao Zheng, Ellen Fry, Feng Yuan, Yaling Liu","doi":"10.1088/1748-9326/ad703f","DOIUrl":"https://doi.org/10.1088/1748-9326/ad703f","url":null,"abstract":"Soil seed banks are the main seed reservoirs globally and are critical for the regeneration of grassland plant populations. Grazing often affects the density and diversity of grassland soil seed banks; however, it is not clear how these effects vary on a global scale with grazing intensity, grazing duration, and climatic conditions. Here, we screened 92 independent published articles and performed a meta-analysis of the extracted data. The effects of grazing on four soil seed bank density and diversity indices were analyzed. Four alpha diversity indices, namely Shannon–Wiener, Margalef, Pielou, and Simpson indices, were selected in this study. The Shannon–Wiener index reflects the species complexity of the community. The Margalef index reflects species richness of the seed bank. The Pielou index reflects whether the number of seeds of all species in the seed bank is evenly distributed, and the Simpson’s index reflects the status of dominant plants in the seed bank. We found that grazing significantly decreased the total density of soil seed banks. Perennial plant seed banks were more affected by grazing than annual plant seed banks. Heavy grazing significantly decreased the Margalef index of seed banks, while moderate grazing significantly decreased the Simpson’s alpha diversity index. Long-term grazing (>10 years) had the greatest impact on Simpson’s alpha diversity index, while medium-term grazing (5–10 years) had a significant negative impact on Shannon–Wiener, Margalef, and Pielou indices. In addition, our results show that grazing has a greater effect on seed banks in arid areas than those in temperate areas. Knowledge of climate-specific effects will contribute to understanding the risk of local extinctions in grassland populations and help decision-makers maintain the health of grassland ecosystems.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"63 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142213581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1088/1748-9326/ad6fba
Shan Xu, Jie Ou, Xinxin Qiao, Zhenzhong Zeng, Junjian Wang
Boreal and temperate forests, spanning cold mid- to high-latitude environments and encompassing about 43% of the global forest area, are highly vulnerable to warming. Understanding the response of soil carbon (C) dynamics in these forests to warming is of paramount importance, yet significant uncertainty remains. In this meta-analysis, data from 97 studies across 65 sites were synthesized to investigate the effects of warming on soil C inputs, pools, and outputs in boreal and temperate forests. Our results reveal that warming increased aboveground biomass (by 33%) and litterfall (by 15%), while decreasing litter mass remaining (by 7%), with no significant change observed in fine root biomass. Furthermore, warming led to a 9% increase in soil total respiration and a 15% increase in autotrophic respiration, yet had no discernible impact on soil organic carbon (SOC) content. The methods, magnitude, and duration of warming were found to regulate the responses of soil C dynamics. Buried heater warming elicited the most pronounced effects among warming methods. Additionally, soil total respiration exhibited an acclimation response to warming magnitude and duration, while litter decomposition rates increased and SOC content and microbial biomass C decreased with escalating warming magnitude. Moreover, greater soil respiration response occurred in temperate forests than in boreal forests. These findings underscore the nuanced and context-dependent nature of soil C dynamics in response to experimental warming, providing critical insights for understanding the role of boreal and temperate forests in future climate change mitigation strategies.
{"title":"Experimental warming affects soil carbon dynamics in boreal and temperate forests: a meta-analysis","authors":"Shan Xu, Jie Ou, Xinxin Qiao, Zhenzhong Zeng, Junjian Wang","doi":"10.1088/1748-9326/ad6fba","DOIUrl":"https://doi.org/10.1088/1748-9326/ad6fba","url":null,"abstract":"Boreal and temperate forests, spanning cold mid- to high-latitude environments and encompassing about 43% of the global forest area, are highly vulnerable to warming. Understanding the response of soil carbon (C) dynamics in these forests to warming is of paramount importance, yet significant uncertainty remains. In this meta-analysis, data from 97 studies across 65 sites were synthesized to investigate the effects of warming on soil C inputs, pools, and outputs in boreal and temperate forests. Our results reveal that warming increased aboveground biomass (by 33%) and litterfall (by 15%), while decreasing litter mass remaining (by 7%), with no significant change observed in fine root biomass. Furthermore, warming led to a 9% increase in soil total respiration and a 15% increase in autotrophic respiration, yet had no discernible impact on soil organic carbon (SOC) content. The methods, magnitude, and duration of warming were found to regulate the responses of soil C dynamics. Buried heater warming elicited the most pronounced effects among warming methods. Additionally, soil total respiration exhibited an acclimation response to warming magnitude and duration, while litter decomposition rates increased and SOC content and microbial biomass C decreased with escalating warming magnitude. Moreover, greater soil respiration response occurred in temperate forests than in boreal forests. These findings underscore the nuanced and context-dependent nature of soil C dynamics in response to experimental warming, providing critical insights for understanding the role of boreal and temperate forests in future climate change mitigation strategies.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"20 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142213582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-11DOI: 10.1088/1748-9326/ad691a
Koorosh Azizi, Jesse L Barnes, John M Anderies and Margaret Garcia
Urban water management is increasingly challenged by the need to balance cost-effectiveness with equity considerations. This study presents a multi-objective approach to water conservation within the Las Vegas valley water district, analyzing a comprehensive dataset of water consumption and socioeconomic indicators across all single-family residences. We assess policy scenarios under two primary objectives: maximizing water savings to enhance economic efficiency and improving water affordability to promote equity. Our analysis reveals that while strategies focused on water savings reduce water use more efficiently, they tend to favor higher-income, predominantly white neighborhoods whereas prioritizing water affordability shifts resources towards lower-income, communities of color. The analysis of intermediate policy scenarios reveals the trade-offs and potential synergies between water savings and affordability. Our findings suggest that local water sustainability can be achieved by allocating resources to both high-demand and socioeconomically disadvantaged households. Highlighting the importance of integrating equity considerations into water management policies, this study provides insights for policymakers in crafting more inclusive and sustainable urban water management practices.
{"title":"Equity implications of efficient water conservation programs","authors":"Koorosh Azizi, Jesse L Barnes, John M Anderies and Margaret Garcia","doi":"10.1088/1748-9326/ad691a","DOIUrl":"https://doi.org/10.1088/1748-9326/ad691a","url":null,"abstract":"Urban water management is increasingly challenged by the need to balance cost-effectiveness with equity considerations. This study presents a multi-objective approach to water conservation within the Las Vegas valley water district, analyzing a comprehensive dataset of water consumption and socioeconomic indicators across all single-family residences. We assess policy scenarios under two primary objectives: maximizing water savings to enhance economic efficiency and improving water affordability to promote equity. Our analysis reveals that while strategies focused on water savings reduce water use more efficiently, they tend to favor higher-income, predominantly white neighborhoods whereas prioritizing water affordability shifts resources towards lower-income, communities of color. The analysis of intermediate policy scenarios reveals the trade-offs and potential synergies between water savings and affordability. Our findings suggest that local water sustainability can be achieved by allocating resources to both high-demand and socioeconomically disadvantaged households. Highlighting the importance of integrating equity considerations into water management policies, this study provides insights for policymakers in crafting more inclusive and sustainable urban water management practices.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"90 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-11DOI: 10.1088/1748-9326/ad6a28
Shiyue Zhang, Gang Zeng, Xiaoye Yang and Zhongxian Li
Climate factors, in addition to human activities, are acknowledged to exert a notable influence on the synoptic PM2.5 variations over eastern China in extensive case studies. Based on observed daily PM2.5 concentrations data, this study reveals the enhanced daily variability (DV) of PM2.5 concentrations over eastern China and identifies its association with mid-latitude sea surface temperature anomalies over the North Atlantic. The dominant daily mode of PM2.5 concentrations identified through empirical orthogonal function analysis accounts for 43.75% of the total variance, with its DV experienced a significant enhancement from 1979 to 2019. The identified enhancement is attributed to the intensified wave train propagation along the mid-latitudes on a time scale of 10–30 d. The eastward propagation of the identified wave train can expose eastern China to recurrent influences of cyclonic and anticyclonic anomalies, resulting in an initial increase and subsequent decrease in PM2.5 concentrations. Statistical analysis and dynamic diagnostics show that the warming of the mid-latitude North Atlantic Ocean enhances the wave train at its source through the local energy exchange, and ultimately leads to an increased DV of PM2.5 concentrations.
在大量案例研究中，除人类活动外，气候因素也被认为对中国东部地区PM2.5的同步变化产生了显著影响。本研究基于观测到的PM2.5日浓度数据，揭示了中国东部地区PM2.5浓度的增强日变率（DV），并确定了其与北大西洋中纬度海面温度异常的关联。通过经验正交函数分析确定的PM2.5浓度主导日模式占总方差的43.75%，其DV在1979年至2019年期间显著增强。所确定的波列向东传播可使华东地区受到气旋和反气旋异常的反复影响，从而导致 PM2.5 浓度的先升后降。统计分析和动态诊断表明，北大西洋中纬度的变暖通过局地能量交换增强了波列的源头，并最终导致 PM2.5 浓度的 DV 值增加。
{"title":"Warming of mid-latitude North Atlantic Sea surface temperature strengthens the daily variability of winter PM2.5 in eastern China","authors":"Shiyue Zhang, Gang Zeng, Xiaoye Yang and Zhongxian Li","doi":"10.1088/1748-9326/ad6a28","DOIUrl":"https://doi.org/10.1088/1748-9326/ad6a28","url":null,"abstract":"Climate factors, in addition to human activities, are acknowledged to exert a notable influence on the synoptic PM2.5 variations over eastern China in extensive case studies. Based on observed daily PM2.5 concentrations data, this study reveals the enhanced daily variability (DV) of PM2.5 concentrations over eastern China and identifies its association with mid-latitude sea surface temperature anomalies over the North Atlantic. The dominant daily mode of PM2.5 concentrations identified through empirical orthogonal function analysis accounts for 43.75% of the total variance, with its DV experienced a significant enhancement from 1979 to 2019. The identified enhancement is attributed to the intensified wave train propagation along the mid-latitudes on a time scale of 10–30 d. The eastward propagation of the identified wave train can expose eastern China to recurrent influences of cyclonic and anticyclonic anomalies, resulting in an initial increase and subsequent decrease in PM2.5 concentrations. Statistical analysis and dynamic diagnostics show that the warming of the mid-latitude North Atlantic Ocean enhances the wave train at its source through the local energy exchange, and ultimately leads to an increased DV of PM2.5 concentrations.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"57 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1088/1748-9326/ad69a6
Ting Wei, Yueli Chen and Hui Wang
Carbon dioxide removal (CDR) is proposed to limit the level of global warming and minimize the impacts of climate crises. However, how permafrost may respond to negative carbon emissions remains unknown. Here, the response of near-surface permafrost in the Northern Hemisphere is investigated based on idealized carbon dioxide (CO2) ramp-up (284.7–1138.8 ppm) and symmetric ramp-down model experiments. The results demonstrate that the timing of the minimum permafrost area lags the maximum CO2 concentration for decades, which is also observed in soil temperatures at different depths and active layer thicknesses (ALTs). When the CO2 concentration is reversed to the preindustrial level, the permafrost area decreases by ∼12% relative to the initial conditions, together with additional warming in the ground temperature at the top of the permafrost, indicating the hysteresis of permafrost to CO2 removal. The most profound hysteretic responses occur at high latitudes for soil temperatures owing to Arctic amplification and at the southern margins of the permafrost zones for permafrost and ALT that largely linked to the climate state. Moreover, the sensitivity of permafrost and the associated thermodynamic factors to CO2 change is generally lower during the CO2 ramp-down phase than during the ramp-up phase, likely due to the release of stored heat on land. The results reveal the behaviour of permafrost in response to negative carbon emissions, which is informative for the projections of permafrost towards carbon neutral targets. In addition, the results may provide a reference for permafrost-related tipping points (e.g. releasing long-term stored greenhouse gases and destabilising recalcitrant soil carbon) and risk management in the future.
有人建议清除二氧化碳（CDR），以限制全球变暖的程度，并将气候危机的影响降至最低。然而，永冻土如何应对负碳排放仍是未知数。本文基于理想化的二氧化碳（CO2）上升（284.7-1138.8 ppm）和对称下降模型实验，研究了北半球近地表永久冻土的响应。结果表明，永久冻土面积最小的时间滞后于二氧化碳浓度最大值达数十年之久，不同深度和活动层厚度（ALTs）的土壤温度也观察到了这一点。当二氧化碳浓度逆转到工业化前水平时，永久冻土面积相对于初始条件减少了 12%，同时永久冻土顶部的地温也额外升高，这表明了永久冻土对二氧化碳清除的滞后性。在高纬度地区，由于北极放大效应，土壤温度的滞后反应最为显著；在永久冻土带南部边缘地区，永久冻土和 ALT 的滞后反应与气候状态密切相关。此外，冻土和相关热力学因子对二氧化碳变化的敏感性在二氧化碳下降阶段普遍低于上升阶段，这可能是由于陆地上储存的热量被释放所致。研究结果揭示了永久冻土在碳负排放情况下的表现，这对预测永久冻土实现碳中和目标具有参考价值。此外，这些结果还可为未来与永久冻土相关的临界点（如释放长期储存的温室气体和破坏土壤碳的稳定性）和风险管理提供参考。
{"title":"Hysteresis of Northern Hemisphere permafrost to carbon dioxide emissions","authors":"Ting Wei, Yueli Chen and Hui Wang","doi":"10.1088/1748-9326/ad69a6","DOIUrl":"https://doi.org/10.1088/1748-9326/ad69a6","url":null,"abstract":"Carbon dioxide removal (CDR) is proposed to limit the level of global warming and minimize the impacts of climate crises. However, how permafrost may respond to negative carbon emissions remains unknown. Here, the response of near-surface permafrost in the Northern Hemisphere is investigated based on idealized carbon dioxide (CO2) ramp-up (284.7–1138.8 ppm) and symmetric ramp-down model experiments. The results demonstrate that the timing of the minimum permafrost area lags the maximum CO2 concentration for decades, which is also observed in soil temperatures at different depths and active layer thicknesses (ALTs). When the CO2 concentration is reversed to the preindustrial level, the permafrost area decreases by ∼12% relative to the initial conditions, together with additional warming in the ground temperature at the top of the permafrost, indicating the hysteresis of permafrost to CO2 removal. The most profound hysteretic responses occur at high latitudes for soil temperatures owing to Arctic amplification and at the southern margins of the permafrost zones for permafrost and ALT that largely linked to the climate state. Moreover, the sensitivity of permafrost and the associated thermodynamic factors to CO2 change is generally lower during the CO2 ramp-down phase than during the ramp-up phase, likely due to the release of stored heat on land. The results reveal the behaviour of permafrost in response to negative carbon emissions, which is informative for the projections of permafrost towards carbon neutral targets. In addition, the results may provide a reference for permafrost-related tipping points (e.g. releasing long-term stored greenhouse gases and destabilising recalcitrant soil carbon) and risk management in the future.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"37 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1088/1748-9326/ad69aa
Xiaohui Tian, Bo Qiu, Yueyang Ni, Jiuyi Chen, Lingfeng Li, Yipeng Cao and Siwen Zhao
The increasing frequency of European heatwaves and the associated impacts on ecosystems have raised widespread concern during the last two decades. The partitioning of surface energy between latent and sensible heat fluxes plays a pivotal role in regulating heat and water exchange between the land surface and the atmosphere. However, the responses of surface energy partitioning during heatwave events and the contributions of changes in energy partitioning to heatwave development have been underexplored. Here, we investigated the responses of surface energy exchange to temperature extremes during four devastating European heatwaves (2003, 2010, 2018, and 2022) based on long‒term observations from 31 flux towers. Our results demonstrated that the divergent responses of surface energy exchange to heatwaves were modulated by vegetation type and background climate in Europe. Forests maintained similar latent heat fluxes as the climatological mean but largely increased sensible heat under heat‒stressed conditions. While grasslands and croplands tended to increase sensible heat by suppressing latent heat during heatwaves, especially under water‒stressed conditions. Furthermore, the changes in surface energy partitioning strengthened positive land‒atmosphere feedbacks during the heatwave period, leading to unprecedented temperature extremes. This study highlights the importance of surface energy partitioning in land‒atmosphere interactions and heatwave developments.
{"title":"Divergent response of energy exchange to heatwaves from flux tower observations among various vegetation types","authors":"Xiaohui Tian, Bo Qiu, Yueyang Ni, Jiuyi Chen, Lingfeng Li, Yipeng Cao and Siwen Zhao","doi":"10.1088/1748-9326/ad69aa","DOIUrl":"https://doi.org/10.1088/1748-9326/ad69aa","url":null,"abstract":"The increasing frequency of European heatwaves and the associated impacts on ecosystems have raised widespread concern during the last two decades. The partitioning of surface energy between latent and sensible heat fluxes plays a pivotal role in regulating heat and water exchange between the land surface and the atmosphere. However, the responses of surface energy partitioning during heatwave events and the contributions of changes in energy partitioning to heatwave development have been underexplored. Here, we investigated the responses of surface energy exchange to temperature extremes during four devastating European heatwaves (2003, 2010, 2018, and 2022) based on long‒term observations from 31 flux towers. Our results demonstrated that the divergent responses of surface energy exchange to heatwaves were modulated by vegetation type and background climate in Europe. Forests maintained similar latent heat fluxes as the climatological mean but largely increased sensible heat under heat‒stressed conditions. While grasslands and croplands tended to increase sensible heat by suppressing latent heat during heatwaves, especially under water‒stressed conditions. Furthermore, the changes in surface energy partitioning strengthened positive land‒atmosphere feedbacks during the heatwave period, leading to unprecedented temperature extremes. This study highlights the importance of surface energy partitioning in land‒atmosphere interactions and heatwave developments.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"45 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1088/1748-9326/ad69a7
Shaolei Tang, Zhiyuan Zhang and Jing-Jia Luo
The South China (SC) late rainy season rainfall (SCLR) is important to people’s livelihoods and properties of this densely populated and economically developed region. Based on observation and reanalysis datasets, this study identifies that the relationship between the SCLR and equatorial Pacific SSTs (EPSSTs) experiences an interdecadal change around the late 1970s. The SCLR is negatively correlated with the eastern EPSSTs during 1948–1977 (the previous epoch) but positively correlated with the central EPSSTs during 1978–2022, especially during the last three decades 1993–2022 (the post epoch). This is due to the interdecadal change in El Niño flavors and EPSSTs-tropical Atlantic SSTs (TASSTs) relationship. With the increasing frequency of central Pacific El Niños in the post epoch, the El Niño-related warm SST anomaly center shifts from the eastern equatorial Pacific (EEP) to the central equatorial Pacific (CEP). Correspondingly, the anomalous cyclone exerted by the CEP warming reaches SC and causes rainfall surplus there (westward propagation pathway). In contrast, the EEP warming in the previous epoch cannot influence the SCLR through the westward propagation pathway, but through shifting the westerly jet southward via heating the tropical troposphere. The southward shifted westerly jet crashes the Qinghai–Tibet Plateau, triggering cyclonic circulations across the northern East Asia and North Pacific, which in turn cause anticyclonic circulations over the western SC and reduce SC rainfall (eastward propagation pathway). On the other hand, the CEP warming in the post epoch barely influence the SCLR through the eastward propagation pathway because of the enhanced negative relationship between EPSSTs and TASSTs.
{"title":"Interdecadal change in the relationship between the South China late rainy season rainfall and equatorial Pacific SSTs","authors":"Shaolei Tang, Zhiyuan Zhang and Jing-Jia Luo","doi":"10.1088/1748-9326/ad69a7","DOIUrl":"https://doi.org/10.1088/1748-9326/ad69a7","url":null,"abstract":"The South China (SC) late rainy season rainfall (SCLR) is important to people’s livelihoods and properties of this densely populated and economically developed region. Based on observation and reanalysis datasets, this study identifies that the relationship between the SCLR and equatorial Pacific SSTs (EPSSTs) experiences an interdecadal change around the late 1970s. The SCLR is negatively correlated with the eastern EPSSTs during 1948–1977 (the previous epoch) but positively correlated with the central EPSSTs during 1978–2022, especially during the last three decades 1993–2022 (the post epoch). This is due to the interdecadal change in El Niño flavors and EPSSTs-tropical Atlantic SSTs (TASSTs) relationship. With the increasing frequency of central Pacific El Niños in the post epoch, the El Niño-related warm SST anomaly center shifts from the eastern equatorial Pacific (EEP) to the central equatorial Pacific (CEP). Correspondingly, the anomalous cyclone exerted by the CEP warming reaches SC and causes rainfall surplus there (westward propagation pathway). In contrast, the EEP warming in the previous epoch cannot influence the SCLR through the westward propagation pathway, but through shifting the westerly jet southward via heating the tropical troposphere. The southward shifted westerly jet crashes the Qinghai–Tibet Plateau, triggering cyclonic circulations across the northern East Asia and North Pacific, which in turn cause anticyclonic circulations over the western SC and reduce SC rainfall (eastward propagation pathway). On the other hand, the CEP warming in the post epoch barely influence the SCLR through the eastward propagation pathway because of the enhanced negative relationship between EPSSTs and TASSTs.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"77 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1088/1748-9326/ad69a9
Hien X Bui, Yi-Xian Li and Dietmar Dommenget
This study investigates a fire weather index (FWI) and its associated components in Australia using the downscaled projects for the Coupled Model Intercomparison Project phase 6 dataset, aiming to understand how they respond to global warming, particularly associated with different phases of the El Niño-Southern Oscillation (ENSO). In the historical simulation, multimodel mean composite results show positive anomalies of FWI during El Niño and negative anomalies during La Niña over most of Australia relative to the neutral year. At the end of the 21st century under the Shared Socioeconomic Pathways (SSP585 scenario), FWI anomalies increased across Australia; however, ENSO wildfire teleconnections weakened (−4.4%) during El Niño but strengthened (+6.0%) during La Niña, especially in northern Australia. Further examination of the contribution from individual environmental variables that enter the FWI shows that increased temperature and drought conditions with warming in La Niña strengthen positive FWI anomalies, thus making fire more favorable in north and central Australia. The impacts of relative humidity and wind speed anomaly changes also favor fire activity toward the north. These results suggest a more robust modulation of FWI in northern Australia by ENSO in a warmer climate; future efforts to predict wildfire will depend on the model’s ability to predict local climate conditions.
{"title":"Controlling factors of wildfires in Australia and their changes under global warming","authors":"Hien X Bui, Yi-Xian Li and Dietmar Dommenget","doi":"10.1088/1748-9326/ad69a9","DOIUrl":"https://doi.org/10.1088/1748-9326/ad69a9","url":null,"abstract":"This study investigates a fire weather index (FWI) and its associated components in Australia using the downscaled projects for the Coupled Model Intercomparison Project phase 6 dataset, aiming to understand how they respond to global warming, particularly associated with different phases of the El Niño-Southern Oscillation (ENSO). In the historical simulation, multimodel mean composite results show positive anomalies of FWI during El Niño and negative anomalies during La Niña over most of Australia relative to the neutral year. At the end of the 21st century under the Shared Socioeconomic Pathways (SSP585 scenario), FWI anomalies increased across Australia; however, ENSO wildfire teleconnections weakened (−4.4%) during El Niño but strengthened (+6.0%) during La Niña, especially in northern Australia. Further examination of the contribution from individual environmental variables that enter the FWI shows that increased temperature and drought conditions with warming in La Niña strengthen positive FWI anomalies, thus making fire more favorable in north and central Australia. The impacts of relative humidity and wind speed anomaly changes also favor fire activity toward the north. These results suggest a more robust modulation of FWI in northern Australia by ENSO in a warmer climate; future efforts to predict wildfire will depend on the model’s ability to predict local climate conditions.","PeriodicalId":11747,"journal":{"name":"Environmental Research Letters","volume":"27 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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