Communications Earth & Environment

Urban forests (i.e. all vegetation present in urban areas), provide environmental and socioeconomic benefits1 to more than half of the global population2. Projected climate change threatens these benefits to society3-5. Here, we assess vulnerability to climate change of 16,006 plant species present in the urban forests of 1,010 cities within 93 countries, using three vulnerability metrics: exposure, safety margin and risk. Exposure expresses the magnitude of projected changes in climate in a given area, safety margin measures species sensitivity to climate change, and risk is the difference between exposure and safety margin6. We identified 9,676 (60.5%) and 8,344 (52.1%) species exceeding their current climatic tolerance (i.e. safety margin) for mean annual temperature (MAT) and annual precipitation (AP), respectively. By 2050, 13,479 (84.2%) and 9,960 (62.2%) species are predicted to be at risk from projected changes in MAT and AP, respectively, with risk increasing in cities at lower latitudes. Our results can aid evaluation of the impacts of climate change on urban forests and identify the species most at risk. Considering future climates when selecting species for urban plantings will enhance the long-term societal benefits provided by urban forests, including their contribution to mitigating the magnitude and impacts of climate change.

Posidonia oceanica meadows, which underpin Mediterranean coastal ecosystems, are undergoing accelerated decline, partly driven by thermal stress. While previous quantitative studies have identified temperature thresholds beyond which seagrass mortality increases sharply, we show the cumulative and sublethal impacts of prolonged warming under fluctuating subthreshold conditions. To capture these effects, we introduce Stress Degree Days (SDD), a physiologically grounded index derived from an experimentally validated mortality rate function. Using sea surface temperature (SST) data, we quantified the cumulative thermal exposure across the Mediterranean Basin from 2000 to 2020. Leveraging high-resolution satellite imagery and deep learning-based habitat mapping, we linked SDD-derived thermal exposure to meadow fragmentation, which is a proxy for seagrass health. Our results show that high thermal stress (> 50%) is concentrated along the southern and eastern Mediterranean, where meadows exhibit more than 40% cover loss and elevated fragmentation, even though maximum SSTs remained below lethal limits (LT50 = 28.9 {degrees}C). This finding highlights the critical role of chronic sublethal thermal stress in driving structural degradation. Future projections under the RCP8.5, business as usual, and the more moderate RCP4.5 climatic scenarios indicate basin-wide regression, with expected cover losses of approximately 80% and 40%, respectively, by 2100, and near-total habitat suitability collapse in the southern regions. Consequently, fragmentation indices are projected to double or triple, further disrupting clonal connectivity, sediment retention, and oxygen export. In summary, by integrating physiological mechanisms, large-scale remote sensing, and climate modeling, the SDD framework identifies thermal hotspots, reveals emergent vulnerability patterns, and offers a predictive tool to guide conservation strategies in warming oceans.

Marine heatwaves are transforming ecosystems, yet their role in driving alternative states--and the conditions that enable these transitions--remains poorly understood. Using 30 years of satellite and underwater data, we assessed the impact of the 2014-2016 Pacific marine heatwaves on giant kelp forests (Macrocystis pyrifera) at their warm range limit in Mexico. By 2016, 88% of forests were lost, with limited recovery by 2023, including an 80 km range contraction at the southern edge. Surveys revealed three alternative states: replacement by heat-tolerant palm kelp (Eisenia arborea) in warmer regions; urchin barrens due to predator overfishing; and, unexpectedly, persistent giant kelp near the southern limit where high temperatures coincide with low human pressure. Pre-existing conditions, such as high urchin and palm kelp densities, shaped these outcomes. These findings show that responses to marine heatwaves are shaped by local ecological and human contexts, requiring tailored climate-adaptation strategies to promote resilience.

The Southern Ocean plays a crucial role in the global carbon budget. Modeling studies propose that the atmospheric CO2 plateau during the Antarctic Cold Reversal (ACR; 14,700 to 12,700 calibrated years before present (cal yr BP)) is related to increased marine productivity. However, proxy evidence relating environmental conditions as well as primary community composition and productivity to carbon drawdown is missing. Our ancient DNA shotgun metagenomic analysis of marine sediments revealed Phaeocystis antarctica (haptophyte) as a key element of the primary producer community. Independent proxy evidence (blooming-related bacteria, Ba/Fe ratio) from the same sediment record point to high productivity in response to enhanced sea-ice seasonality caused by ACR cooling. Post ACR, abrupt Phaeocystis community loss shows how sensitive this ecosystem is to warming, potentially representing a key tipping element that may be further enhanced by the Phaeocystis-related sulfur cycle-climate feedback. As an analogy for present warming, it highlights the importance of regions with high seasonal sea-ice variability and Phaeocystis-dominance, such as the Ross Sea, for stabilizing atmospheric CO2 content. Additionally, our shotgun metagenomic data portray complex Holocene ecosystem establishment including key Antarctic taxa such as penguins, whales, and Antarctic fishes with implications for ongoing conservation efforts.

How dissolved organic matter (DOM) responds to climate warming is critical for understanding its effectiveness as a natural climate solution. Here, we use a highly resolved dataset of 821 DOM samples covering the surface waters to the deep Atlantic, Southern, and Pacific oceans to examine molecular-level responses to warming water temperatures, i.e. their thermal responses. In general, the strength and diversity of thermal responses among individual molecules both decline towards the deep waters, but they show decreasing and increasing trends with more recalcitrant molecules in concentration, respectively. Their contrasting trends concur with the more important role of photochemical processes in explaining the diversity of thermal responses than the strength. By projecting global ocean thermal responses from 1950-2020, we predict increases in the diversity are unexpectedly largest at deeper depths (> 1,000 m). Such increases could elevate recalcitrant deep-ocean carbon sink by approximately 10 Tg C yr-1 which accounts for > 5% of the carbon flux survived to the deep ocean. Our findings highlight the importance of photochemical legacies in driving DOM thermal responses and further help predict the future oceanic carbon sink under global change.

Tropical forests store roughly half of terrestrial carbon, yet carbon estimates in regenerating and disturbed forests remain highly uncertain. A major source of bias is the prevalence of fast-growing, canopy-forming monocots--such as bamboo, palms, and bananas--that are often misclassified as trees. These "grassy trees" achieve canopy dominance but lack secondary growth, violating woody allometries used in most biomass models. Although NASAs GEDI mission has transformed large-scale biomass mapping with spaceborne LiDAR, its products rely on coarse plant functional types (PFTs), causing grassy-tree-dominated canopies to be absorbed into evergreen broadleaf tree (EBT) classes. Using a texture-based Sentinel-2 classifier, we isolated bamboo-dominated forests within GEDI EBT products in Xishuangbanna, China. GEDI observations show that bamboo canopies are structurally distinct from tree-dominated forests and lead to systematic carbon overestimation of 20-44 Mg C ha-{superscript 1} relative to empirical benchmarks. Our framework improves carbon accounting in structurally heterogeneous forests while remaining adaptable for place-based management.

Climate change is inducing rapid transformations in marine ecosystems, with a pronounced effect on top predators like loggerhead sea turtles (Caretta caretta). Loggerheads responsiveness to temperature fluctuations underscores their significance as a climate sentinel species. We present the first record of a loggerhead sea turtle in Monterey Bay, California, USA, documented through Local Ecological Knowledge (LEK) and community or citizen science (CS), highlighting the pivotal role of these approaches in documenting species occurrences beyond anticipated habitats during climatic anomalies. In rapidly changing conditions, rigorously documented CS and LEK offer a crucial complement to conventional scientific methods, providing high-quality data with extensive coverage-- especially for elusive species--and yielding insights into emerging phenomena.

Freshwater biodiversity is declining at a pace that outstrips the capacity of existing monitoring approaches both in temporal and spatial dimensions, highlighting the urgent need for rapid and scalable assessment and attribution of biodiversity states and changes. Here, we present one of the first global assessments and unified analyses of riverine fish biodiversity using environmental DNA (eDNA) collected from 1818 sites across 113 river systems. We quantified species richness, functional redundancy, phylogenetic diversity, and genetic sequence diversity, and related them to drainage characteristics. Our results showed that eDNA effectively captured global patterns of multi-faceted riverine fish biodiversity and disentangled the roles of climate and human activities in shaping biodiversity-area relationships. Catchments in warmer climates consistently enhanced biodiversity accumulation with area, while higher human activity intensity weakened this scaling. Species richness, functional, and genetic sequence diversity exhibited stronger negative responses to human activities in larger catchments. In contrast, phylogenetic diversity showed the strongest negative effects in smaller catchments with these impacts diminishing as catchment area increased, highlighting the facet-dependent nature of biodiversity responses to environmental gradients. Our findings demonstrate the power of eDNA-based datasets for harmonized, multi-faceted biodiversity assessments, offering a scalable approach for detecting and attributing biodiversity change and informing conservation strategies under accelerating global change.

Timing, duration, and severity of marine heatwaves are changing rapidly in response to anthropogenic climate change, thereby increasing the frequency of coral bleaching events. Mass coral bleaching events occur because of cumulative heat stress, which is commonly quantified through Degree Heating Weeks (DHW). Here we introduce CoralBleachRisk, a daily-resolution global dataset that characterises sea surface temperatures, heat stress anomalies, and the timing, duration, and magnitude of severe coral bleaching conditions from the recent past (1985) to the future (2100) under three contrasting Shared Socioeconomic Pathways. Our projections are downscaled to a 0.5{degrees} resolution (~50km), bias-corrected and validated using remotely sensed data of sea surface temperatures and a global dataset of historical coral bleaching events. An accompanying online software tool allows non-specialist users to access aggregated metrics of coral bleaching risk and generate time series projections of coral vulnerability for Earths coral reefs. More broadly, our dataset enables regional to global comparisons of future trends in severe coral bleaching risk and the identification of potential climate refugia for corals.

AbstractThe Tara Pacific expedition (2016-2018) sampled coral ecosystems around 32 islands in the Pacific Ocean and the ocean surface waters at 249 locations, resulting in the collection of nearly 58,000 samples. The expedition was designed to systematically study warm coral reefs and included the collection of corals, fish, plankton, and seawater samples for advanced biogeochemical, molecular, and imaging analysis. Here we provide a complete description of the sampling methodology, and we explain how to explore and access the different datasets generated by the expedition. Environmental context data were obtained from taxonomic registries, gazetteers, almanacs, climatologies, operational biogeochemical models, and satellite observations. The quality of the different environmental measures has been validated not only by various quality control steps but also through a global analysis allowing the comparison with known environmental large-scale structures. Such a wide released datasets opens the perspective to address a wide range of scientific questions.

Glycerol dialkyl glycerol tetraethers (GDGTs), membrane lipids produced by archaea and some bacteria, are widely used in paleoclimate reconstructions due to their empirical relationship with temperature. However, their application in lakes is complicated by uncertainties in source attribution and environmental controls on their distribution. To address these constraints, we analyzed both branched and isoprenoid GDGTs (brGDGTs and isoGDGTs) in settling particles collected over 19 months using sediment traps at four depths (10, 15, 25 and 35 m) in Lake Lugu, a deep, stratified alpine lake in southwestern China. GDGT fluxes showed synchronous spatiotemporal variations across depths, with higher values during winter mixing than summer stratification, suggesting in situ production enhanced by nutrient upwelling during lake overturn. Correlations between GDGT distributions and high-resolution water temperature profiles revealed strong temperature sensitivity in isoGDGTs, particularly the Ring Index (RI), with peak correlations linked to mean temperatures [~]20 days prior to trap recovery, indicating a clear temporal lag in GDGT-temperature relationship. Moreover, stronger correlations with temperatures at overlying depths, implying vertical transport of isoGDGTs and a dominant autochthonous origin from the upper water column. In contrast, brGDGTs displayed weak or non-significant temperature dependence, likely reflecting distinct microbial sources or other controlling factors. These findings underscore the utility of isoGDGT-based proxies, particularly RI, while highlighting the importance of accounting for spatiotemporal offsets in GDGTs production when reconstructing paleotemperatures in deep, stratified lakes.

The eddy covariance technique has revolutionized our understanding of ecosystem-atmosphere interactions. Eddy covariance studies often use a "paired" tower design in which observations from nearby towers are used to understand how different vegetation, soils, hydrology, or experimental treatment shape ecosystem function and surface-atmosphere exchange. Paired towers have never been formally defined and their global distribution has not been quantified. We compiled eddy covariance tower information to find towers that could be considered paired. Of 1233 global eddy covariance towers, 692 (56%) were identified as paired by our criteria. Paired towers had cooler mean annual temperature (mean = 9.9 {degrees}C) than the entire eddy covariance network (10.5 {degrees}C) but warmer than the terrestrial surface (8.9 {degrees}C) from WorldClim 2.1, on average. The paired and entire tower networks had greater average soil nitrogen (0.57-0.58 g/kg) and more silt (36.0-36.4%) than terrestrial ecosystems (0.38 g/kg and 30.5%), suggesting that eddy covariance towers sample richer soils than the terrestrial surface as a whole. Paired towers existed in a climatic space that was more different from the global climate distribution sampled by the entire eddy covariance network, as revealed by an analysis of the Kullback-Leibler divergence, but the edaphic space sampled by the entire network and paired towers was similar. The lack of paired towers with available data across much of Africa, northern, central, southern, and western Asia, and Latin America with few towers in savannas, shrublands, and evergreen broadleaf forests point to key regions, ecosystems, and ecosystem transitions in need of additional research. Few if any paired towers study the flux of ozone and other atmospherically active trace gases at the present. By studying what paired towers measure - and what they do not - we can make infrastructural investments to further enhance the value of FLUXNET as it moves toward its fourth decade.

Freshwater biodiversity is critically affected by human modifications of terrestrial land use and land cover (LULC)1,2. Yet, knowledge of the spatial extent and magnitude of LULC-aquatic biodiversity linkages is still surprisingly limited, impeding the implementation of optimal management strategies3. Here, we compiled fish diversity data across a 160,000-km2 subtropical river catchment in Thailand characterized by exceptional biodiversity4 yet intense anthropogenic alterations5, and attributed fish species richness and community composition to contemporary terrestrial LULC across the catchment. We estimated a spatial range of LULC effects extending up to about 20 km upstream from sampling sites, and explained nearly 60 % of the variance in the observed species richness, associated with major LULC categories including croplands, forest, and urban areas. We find that integrating both spatial range and magnitudes of LULC effects is needed to accurately predict fish species richness. Further, projected LULC changes showcase future gains and losses of fish species richness across the river network and offer a scalable basis for riverine biodiversity conservation and land management, allowing for potential mitigation of biodiversity loss in highly diverse yet data-deficient tropical to sub-tropical riverine habitats.

Mountain ecosystems face unprecedented pressures from anthropogenic activities and climate change, challenging the productivity of these vital habitats. In the Tien Shan mountains, understanding localized responses to these pressures is often hindered by the coarse spatiotemporal resolutions of available data. To address this, we combined high-resolution satellite imagery (1997-2021) to map land-cover dynamics in the Naryn oblast, Kyrgyzstan across a gradient of grazing intensities. We classified and quantified land-cover distribution over 24 years, investigating the roles of topography, elevation, and anthropogenic disturbances as drivers of change. Our results identify intermediate elevations, high degrees of disturbance, and the interaction between the two as the primary contributors to recent transitions in grassland, forest, and barren habitats. By integrating Landsat analysis-ready data, European Space Agency WorldCover dataset and digital elevation models at fine spatial scales, we provide valuable contemporary and historical landscape and habitat-level insights and a high-resolution framework for disentangling climate-driven shifts from land-use impacts. These findings highlight the urgency of localized management in remote, data-poor regions where rapid environmental change threatens both biodiversity and pastoral livelihoods. Our work serves as a critical baseline for characterizing the adaptability of semi-arid mountain rangelands under escalating global and regional pressures.

Large tropical river dam projects are set to accelerate over the forthcoming decades to satisfy growing demand for energy, irrigation and flood control. When tropical rivers are dammed, the immediate impacts are well studied, but the long-term (decades-centuries) consequences of impoundment remain poorly known. Here, we gather historical and paleoecological data from Gatun Lake, formed by the building of the Gatun Dam (Panama Canal, Panama) over 100 years ago, to reconstruct the limnological evolution of the system in response to individual and linked stressors (river damming, forest flooding, deforestation, invasive species, pollution and hydro-climate). We found that after a century of dam construction parallels associated with the natural hydrological functioning of river floodplains persist. Hence, hydrology remains the most important temporal structural factor positively stimulating primary productivity, deposition of new minerals, and reduction of water transparency during wet periods. During dry periods, clear water and aerobic conditions prevail and nutrients transform into available forms in the detrital-rich reductive sediments. We highlight the importance of climate change as an ultimate rather than proximate anthropogenic factor for sustainable management options of tropical dams.

Soil biodiversity is essential for terrestrial ecosystems, influencing nutrient cycling, carbon sequestration, agricultural productivity, and resilience to environmental changes. Yet, it faces significant threats from land-use changes, pollution, agricultural intensification, and climate change. Effective predictive modeling tools are urgently needed to inform conservation and management strategies. Although species distribution models (SDMs) have been successful for aboveground biodiversity, their application to soil biodiversity is limited by scarce large-scale datasets with spatial mismatches between environmental data and soil habitats. Recent advances, including environmental DNA (eDNA) metabarcoding, now allow extensive multi-taxa assessments of soil biodiversity. Simultaneously, remote sensing technologies provide high-resolution spatial data, potentially overcoming traditional coarse-gridded environmental limitations. This study evaluates Earth Observation Foundation (EOF) models, deep learning models pretrained on massive remote sensing datasets to summarize earth observation images into embeddings, to predict multi-trophic soil biodiversity in the French Alps. We compare models using EOF-derived embeddings from orthophotos with coarse-gridded and high-quality in-situ variables. We modeled relative abundance for 51 trophic groups across seven taxa using Random Forest, Light Gradient Boosting Machine, and Artificial Neural Networks, evaluating four data configurations: coarse-gridded environmental data, high-quality in-situ data, EOF embeddings, and a hybrid embedding-tabular approach. High-quality in-situ climate and soil data consistently delivered the highest predictive accuracy, especially for microbial and fungal groups. EOF embeddings provided valuable spatial context but did not surpass in-situ data performance, showing partial redundancy. Integrating remote sensing data can enhance biodiversity modeling in areas lacking detailed in-situ measurements, underscoring their complementary role in ecological assessments.

Construction minerals - sand, gravel, limestone - are the most extracted solid raw materials1 and account for most of the worlds anthropogenic mass, which as of 2020 outweighed all of Earths living biomass2. However, knowledge about the magnitude, geography, and profile of this widespread threat to biodiversity remains scarce and scattered3-6. Combining long-term data from the IUCN Red List and new species descriptions we provide the first systematic evaluation of species threatened by mining of construction minerals globally. We found 1,047 species in the Red List impacted by this type of mining, of which 58.5% are threatened with extinction and four species already went extinct. We also identified 234 new species descriptions in 20 biodiversity hotspots reporting impacts from mining. Temporal trends in the assessments highlight the increased saliency of this threat to biodiversity, whose full extent may well reach over 24,000 animal and plant species. While rock quarrying mostly threatens karst biodiversity and narrow-ranged species, sand and gravel extraction is a more prominent threat to freshwater and coastal systems. This study provides the first evidence base to support a global strategy to limit the biodiversity impacts of construction mineral extraction.

Marine plankton form complex communities of interacting organisms at the base of the food web, which sustain oceanic biogeochemical cycles, and help regulate climate. Though global surveys are starting to reveal ecological drivers underlying planktonic community structure, and predicted climate change responses, it is unclear how community-scale species interactions will be affected by climate change. Here we leveraged Tara Oceans sampling to infer a global ocean cross-domain plankton co-occurrence network - the community interactome - and used niche modeling to assess its vulnerabilities to environmental change. Globally, this revealed a plankton interactome self-organized latitudinally into marine biomes (Trades, Westerlies, Polar), and more connected poleward. Integrated niche modeling revealed biome-specific community interactome responses to environmental change, and forecasted most affected lineages for each community. These results provide baseline approaches to assess community structure and organismal interactions under climate scenarios, while identifying plausible plankton bioindicators for ocean monitoring of climate change.

The Amazon rainforest, which stores approximately 120 billion tons of carbon and contributes around 16% of global terrestrial photosynthetic productivity, plays a pivotal role in global carbon cycling. Unlike temperate and boreal forests, tropical forests exhibit a bimodal photosynthetic pattern, characterized by distinct peaks in the first and second halves of the year. However, the intra-annual differences in photosynthetic responses to hydrothermal variations between these two periods in the Amazon rainforest remain largely unexplored. Here, utilizing satellite-derived photosynthetic proxies alongside ground-based flux tower observations from 2001 to 2020, we investigated the differences in photosynthetic responses to hydrothermal variations between the first and second halves of the year in the Amazon rainforest. Our observations revealed weaker temperature limitations but stronger precipitation limitations on photosynthesis in the second half of the year compared to the first half. Temperature constraints on photosynthesis have progressively weakened in both periods, while precipitation limitations have intensified, particularly in the latter half. Although the optimal temperature for photosynthesis is higher in the second half of the year, it is reached earlier, resulting in a sharper decline in photosynthetic productivity over the past two decades. Our findings reveal a shift from temperature to precipitation limitation in the Amazon, underscoring intra-annual asymmetry in vulnerability to intensifying heatwaves and droughts and calling for its explicit integration into management strategies and predictive models.

Foraminiferal environmental DNA (eDNA) assemblages have recently emerged as a robust and complementary proxy for relative sea level (RSL) reconstruction. However, unlike traditional morphological methods, eDNA assemblages are influenced by diverse DNA sources, including propagules and juveniles, whose effects on RSL reconstruction remain poorly understood. To assess how foraminiferal eDNA from different life stages vary in taxa composition and impact RSL reconstruction, we analyzed foraminiferal eDNA from bulk, 500-63 m and <63 m size fraction sediments from mangrove and mudflat environments in subtropical Hong Kong. The eDNA assemblages in size-fractioned sediments displayed distinct patterns from those in bulk sediment eDNA across different environments. The propagule and juvenile-derived eDNA <63 m fraction exhibited a similar community structure to bulk eDNA in mudflat environments but diverged in mangrove environments, indicating a greater contribution of propagule and juvenile eDNA to the total eDNA pool in the mudflat environment. We applied Bayesian transfer function modeling to estimate the elevation of samples using different size fractions. eDNA assemblages from the <63 m fraction systematically underpredicted elevation in mangrove environments, while elevations inferred from the 500-63 m fraction and bulk sediment eDNA were accurate. Conversely, all eDNA assemblages in the mudflat-mangrove transitional zone led to the overprediction of RSL. These findings confirm the reliability of bulk sediment eDNA for RSL reconstruction in mangrove environments, while highlighting the need for caution when reconstructing RSL in transitional zones.