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Accurately estimating the forest canopy height is essential for quantifying forest biomass and carbon storage. Recently, the ICESat-2 and GEDI spaceborne LiDAR missions have significantly advanced global canopy height mapping. However, due to inherent sensor limitations, their footprint-level estimates often show systematic bias. Tall forests tend to be underestimated, while short forests are often overestimated. To address this issue, we used coincident G-LiHT airborne LiDAR measurements to correct footprint-level canopy heights from both ICESat-2 and GEDI, aiming to improve the canopy height retrieval accuracy across Puerto Rico’s tropical forests. The bias-corrected LiDAR dataset was then combined with multi-source predictors derived from Sentinel-1/2 and the 3DEP DEM. Using these inputs, we trained a canopy height inversion model based on the AutoGluon stacking ensemble method. Accuracy assessments show that, compared to models trained on uncorrected single-source LiDAR data, the new model built on the bias-corrected ICESat-2–GEDI fusion outperformed in both overall accuracy and consistency across canopy height gradients. The final model achieved a correlation coefficient (R) of 0.80, with a root mean square error (RMSE) of 3.72 m and a relative RMSE of 0.22. The proposed approach offers a robust and transferable approach for high-resolution canopy structure mapping and provides valuable support for carbon accounting and tropical forest management.

Widespread lake drainage can lead to large-scale drying in Arctic lake-rich areas, affecting hydrology, ecosystems and permafrost carbon dynamics. To date, the spatio-temporal distribution, driving factors, and post-drainage dynamics of lake drainage events across the Arctic remain unclear. Using satellite remote sensing and surface water products, we identify over 35,000 (~0.6% of all lakes) lake drainage events in the northern permafrost zone between 1984 and 2020, with approximately half being relatively understudied non-thermokarst lakes. Smaller, thermokarst, and discontinuous permafrost area lakes are more susceptible to drainage compared to their larger, non-thermokarst, and continuous permafrost area counterparts. Over time, discontinuous permafrost areas contribute more drained lakes annually than continuous permafrost areas. Following drainage, vegetation rapidly colonizes drained lake basins, with thermokarst drained lake basins showing significantly higher vegetation growth rates and greenness levels than their non-thermokarst counterparts. Under warming, drained lake basins are likely to become more prevalent and serve as greening hotspots, playing an important role in shaping Arctic ecosystems. The Arctic is dotted with lakes, including thermokarst lakes highly threatened by climate change. Here, the authors investigate 35 years of lake drainage events and related vegetation trends across the Arctic, finding differences between thermokarst and non-thermokarst lake drainage events.

The Arctic is warming far faster than the global average, threatening the release of large amounts of carbon presently stored in frozen permafrost soils. Increasing Earth’s albedo by the injection of sulfate aerosols into the stratosphere has been proposed as a way of offsetting some of the adverse effects of climate change. We examine this hypothesis in respect of permafrost carbon-climate feedbacks using the PInc-PanTher process model driven by seven earth system models running the Geoengineering Model Intercomparison Project (GeoMIP) G4 stratospheric aerosol injection scheme to reduce radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Permafrost carbon released as CO 2 is halved and as CH 4 by 40% under G4 compared with RCP4.5. Economic losses avoided solely by the roughly 14 Pg carbon kept in permafrost soils amount to about US$ 8.4 trillion by 2070 compared with RCP4.5, and indigenous habits and lifestyles would be better conserved. Rising temperatures in the Arctic can lead to the release of vast amounts of carbon stored in permafrost soils. Here the authors show that stratospheric sulfate aerosol injection geoengineering can help to avoid about 14 gigatons of carbon release and US$8.4 trillion in economic losses by 2070 compared to RCP4.5 emissions.

Forest aboveground biomass (AGB) is a key component of terrestrial carbon storage, essential for understanding the carbon cycle and evaluating carbon sink potential. However, estimating long-term AGB in tropical forests and detecting its spatial and temporal trends remain challenging due to observational gaps and methodological constraints. Here, we integrate GEDI L4B gridded biomass data with features from MODIS, PALSAR/PALSAR-2, SRTM, and climate datasets, and apply the AutoGluon ensemble learning framework to develop AGB retrieval models. We generated annual AGB maps at 1 km resolution for Borneo’s forests from 2007 to 2023, achieving high predictive accuracy (R2 = 0.92, RMSE = 32.84 Mg/ha, rRMSE = 21.06%). Residuals were generally balanced and close to a symmetric distribution, indicating no strong bias within the moderate biomass range (50–350 Mg/ha). However, in very high-biomass stands, the model tended to underestimate AGB, reflecting saturation effects that persist despite clear improvements over existing products. Estimated mean AGB values ranged from 180.52 to 214.09 Mg/ha, with total AGB varying between 13.05 and 14.10 Pg. Trend analysis using Sen’s slope and the Mann–Kendall test revealed significant AGB trends in 31.31% of forested areas, with 68.76% showing increases. This study offers a robust and scalable framework for continuous tropical forest carbon monitoring, providing critical support for carbon accounting, forest management, and policy-making.

Accurate identification of bare soil exposure and quantification of associated dust emissions are essential for understanding land degradation and air quality risks in intensively farmed regions. This study develops a monthly monitoring and modeling framework to quantify bare soil dynamics and wind erosion-induced particulate matter (PM) emissions across Shandong Province from 2017 to 2024. By integrating Sentinel-1/2 imagery, climate reanalysis, terrain and soil data, and employing a stacking ensemble classification model, we mapped bare soil areas at 10 m resolution with an overall accuracy of 93.1%. The results show distinct seasonal variation, with bare soil area peaking in winter and early spring, exceeding 25,000 km2 or 15% of the total area, which is far above the 6.4% estimated by land cover products. Simulations using the CLM5.0 dust module indicate that annual PM10 emissions from bare soil averaged (2.72 ± 1.09) × 105 tons across 2017–2024. Emissions were highest in March and lowest in summer months, with over 80% of the total emitted during winter and spring. A notable increase in emissions was observed after 2022, likely due to more frequent extreme wind events. Spatially, emissions were concentrated in coastal lowlands such as the Yellow River Delta and surrounding saline–alkali lands. Our approach explicitly advances traditional methods by generating monthly 10 m bare soil maps and linking satellite-derived dynamics with process-based dust emission modeling, providing a robust basis for targeted dust control and land management strategies.

Lake drainage is a key manifestation of permafrost degradation with implications for hydrology, landscape dynamics and carbon feedbacks. Lake drainage occurs through two distinct mechanisms, namely lateral drainage and internal drainage. Here, we identified 3,969 lake drainage events from 2001 to 2020 across the northern permafrost region using high‐resolution, multi‐temporal satellite imagery. For each drainage event, we determined its specific timing and mechanism, enabling the first circumpolar classification of lake drainage types at monthly resolution. Lateral drainage accounted for 90.6% of all cases and peaked in June, aligning with increased snowmelt and precipitation in continuous permafrost regions. In contrast, internal drainage events were concentrated in March, when soils begin to thaw in sporadic and isolated permafrost zones with limited surface water input. These findings highlight distinct seasonal and climatic drivers of lake drainage and underscore the need to differentiate between surface and subsurface pathways when assessing permafrost landscape responses.

Influenced by climate change, numerous lakes in permafrost regions are draining, showing significant spatial variability. This study focuses on St. Lawrence Island, where over the last two decades, 771 of 3,271 lakes have drained—a rate around 40 times higher than across the entire northern permafrost region. The surge in lake drainage began in 2018, coinciding with record low sea ice extent in the Bering Sea and unprecedented bird mortalities. Using satellite imagery and machine learning methods, we analyzed drainage events to identify the climatic drivers and potential climate thresholds affecting the island's lake ecosystems. Our findings indicate that autumn peak temperatures above 6°C more than triple the drainage probability, and warming‐induced permafrost thawing may be the direct driver of lake drainage. This research highlights the vulnerability of Arctic lake ecosystems to climate change and assists in developing predictive models for permafrost response, crucial for mitigating impacts on Arctic communities. Plain Language Summary St. Lawrence Island in the Bering Strait has experienced a drastic increase in lake drainage since 2018, suggesting that the region may be reaching a critical environmental threshold or tipping point. This study used satellite images to track changes in over 3,000 lakes over two decades, discovering that warmer autumns with temperatures above 6°C greatly increase the chance of lakes draining. This indicates that the region's permafrost is becoming unstable due to higher temperatures. Permafrost thawing happens because the increased warmth causes the ice within the permafrost to melt, leading to the collapse and drainage of lakes. Such changes are important not only because they transform the local landscape but also because they can impact the people and wildlife depending on these lakes for survival. Understanding these patterns helps predict future changes and assists in preparing for and possibly preventing the negative impacts of these environmental changes. This study highlights how global warming can lead to significant changes in Arctic regions, which can have lasting effects on both the environment and human communities. Key Points Over two decades, a quarter of St. Lawrence Island's lakes have drained, a rate 40 times higher than the entire northern permafrost region Since 2018, the frequency of lake drainage events has increased tenfold, likely linked to autumn heatwaves and permafrost thawing Lake drainage probability more than triples when autumn maximum temperatures exceed 6°C, pushing lake ecosystems beyond tipping points

Climate change is the challenge of the century, and achieving the goals of the Paris Agreement will require worldwide cooperation and mutual effort. Over 120 countries have made their net-zero commitments, and quantifying the social cost of carbon (SCC), i.e. the climate damage caused by an additional ton of CO 2 emissions, under a carbon-neutral pathway would provide a carbon price benchmark for policymakers. Here, we set in detail the emission trajectories of different jurisdictions under a carbon-neutral pathway based on the submitted nationally determined contributions. We then assess global and regional warming, climate change damages, and the SCC with the Policy Analysis of Greenhouse Effect integrated assessment model. We find a peak warming of about 2.1 °C relatives to pre-industrial levels in this century under our carbon-neutral emission pathway. And even if all countries meet their carbon-neutral commitments, this would not be sufficient to limit global warming to 1.5 °C relative to pre-industrial levels. We compare the SCC using fixed discount rates, dynamic discounting, and an equity weighting approach. Notably, the introduction of equity weights would increase the estimated SCC from 79 (11–186) to 291 (83–592) US$ per tCO 2 . Climate change damages will be borne primarily by warmer and poorer countries, and this profound inequality would likely undermine efforts to eradicate extreme poverty. Statistics on current carbon taxes and carbon trading prices show that they are notably lower than global or even regional SCCs, suggesting that the current system does not adequately reflect the global externalities of CO 2 emissions. More studies are needed to assess the equity aspects of climate change impacts, to help refine mechanisms to align domestic interests with global interests, and to facilitate the implementation of national carbon-neutral commitments in place.

Crohn's disease is a chronic, progressive inflammatory condition of the gastrointestinal tract that requires long-term assessment of disease activity. There is a growing need for convenient serum biomarkers to reduce the need for invasive endoscopic evaluations. Our study aims to explore the predictive value of serum biomarkers, specifically total bilirubin, uric acid, and the C-reactive protein/albumin ratio, for disease activity in Crohn's disease. We conducted a retrospective study at the Second Hospital of Anhui Medical University (China), consisting of 170 patients with Crohn's disease and 100 healthy controls. Clinical characteristics and laboratory biomarkers were collected and analyzed. Among the patients, 77 active Crohn's disease patients who had complete follow-up data were included in a longitudinal analysis to assess biomarker dynamics. Compared to healthy controls, Crohn's disease patients exhibited lower bilirubin and albumin levels, but higher C-reactive protein and C-reactive protein/albumin ratio, trends that intensified with disease progression. Following therapy, albumin, C-reactive protein and C-reactive protein/albumin ratio changed significantly in both remission and active groups, whereas a significant increase in total bilirubin was exclusive to the remission group. Receiver operating characteristic analysis indicated that C-reactive protein/albumin ratio had the highest discriminatory power for disease activity (area under the curve [AUC]= 0.903), outperforming C-reactive protein alone (AUC = 0.894), albumin (AUC = 0.719) and total bilirubin (AUC = 0.648). Regarding uric acid, no significant associations were identified overall, apart from a single weak correlation in Spearman's analysis. Our findings support a potential serological remission hypothesis for Crohn's disease, characterized by a post-treatment rise in total bilirubin, together with a decrease in C-reactive protein to approximately 5.3 mg/L and the C-reactive protein/albumin ratio to about 0.136. This hypothesis warrants prospective validation.

Butyrate is one of the most important intermediates during anaerobic digestion of protein wastewater, and its oxidization is considered as a rate-limiting step during methane production. However, information on syntrophic butyrate-oxidizing bacteria (SBOB) is limited due to the difficulty in isolation of pure cultures. In this study, two anaerobic chemostats fed with butyrate as the sole carbon source were operated at different dilution rates (0.01/day and 0.05/day). Butyrate- and acetate-oxidizing bacteria in both chemostats were investigated, combining DNA-Stable Isotope Probing (DNA-SIP) and 16S rRNA gene high-throughput sequencing. The results showed that, in addition to known SBOB, Syntrophomonas, other species of unclassified Syntrophomonadaceae were putative butyrate-oxidizing bacteria. Species of Mesotoga, Aminivibrio, Acetivibrio, Desulfovibrio, Petrimonas, Sedimentibacter, unclassified Anaerolineae, unclassified Synergistaceae, unclassified Spirochaetaceae, and unclassified bacteria may contribute to acetate oxidation from butyrate metabolism. Among them, the ability of butyrate oxidation was unclear for species of Sedimentibacter, unclassified Synergistaceae, unclassified Spirochaetaceae, and unclassified bacteria. These results suggested that more unknown species participated in the degradation of butyrate. However, the corresponding function and pathway for butyrate or acetate oxidization of these labeled species need to be further investigated.