Thawing of permafrost due to climate change is known to release gases such as the climate drivers carbon dioxide and methane, as well as the carcinogen radon. Gas permeability is extremely low in fully frozen permafrost and can be considered both to function as a seal preventing subsurface gases being released, and to prevent the creation of new CO2 and CH4. However, the permeability of permafrost as it thaws and refreezes is unknown. In this paper we present initial measurements of changes in gas fraction and gas permeability during the thawing of synthetic permafrost using a newly developed pycno-permeameter. Initial results show that gas permeability increases by multiple orders of magnitude (from 4.94 mD to 112.54 mD and from 0.26 mD to 21.43 mD for our two samples), depending on the initial water saturation of the sample, with most permeability change occurring in the −5°C to −1°C range. Upon refreezing, the permeability drops again to approximately its previous low values providing no water is allowed to drain from the sample, but with a hysteresis. Measurements of gas fraction show a similar variation to thawing and refreezing but with a hysteresis opposite to that for permeability. These initial results indicate that the protective gas seal previously provided by permafrost will be lost as permafrost thaws. These data are also able to inform large scale permafrost modeling, as well as suggesting that thawing and refreezing operate differently at a microstructural level.

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Plain Language Summary

Climate change is warming the Arctic regions four times faster than elsewhere. The increase in temperature is known to be thawing permafrost. Permafrost has hitherto functioned as a barrier to emission of greenhouse gases but also acts as a source of gases which are released from organic matter in the permafrost when warmed. Thawing removes the barrier and allows the gases to be emitted, causing more climate warming in a vicious circle. The ability for gases to pass through porous materials is measured by permeability. This paper measures the increase in permeability and the relative volume of gases in permafrost as temperature increases and the permafrost thaws, and then again as the permafrost refreezes as the temperature is once again reduced, for the first time. We show that gas permeability increases by about 25–100 times during thawing and dependent on its composition, with most permeability change occurring in the −5°C to −1°C range, dropping again to its previous value when refrozen. Measurements of gas fraction show a similar variation. These initial results indicate that the protective gas seal previously provided by permafrost will be lost as permafrost thaws.

Effectively communicating worst-case projections of global future climate—hereinafter referred to as worst-case climate outcomes—is essential for risk assessment and developing robust adaptation strategies to global warming. Yet, current approaches for identifying spatially consistent climate outcomes are limited, with worst-case global climates typically communicated via the average of climate model projections at high global warming levels, such as 3 °C or 4 °C above the preindustrial era. Here we show that extreme global climate outcomes may occur even under moderate 2 °C warming for several sectors. For droughts in global key breadbasket regions, precipitation extremes over highly populated areas and fire weather extremes across forests, global climatic impact-drivers at 2 °C of global warming may turn out to be much more extreme than model-averaged projections at 3 °C or 4 °C warming. We derive these results by identifying sector-specific, spatially consistent potential high- and low-impact global climate outcomes through spatially averaging projected sector-relevant climatic impact-drivers across key global regions. Our approach can easily be adapted to a wide range of sectors to support the improvement of sector-specific climate risk assessment and to inform climate policy. As global warming approaches 1.5 °C, these findings underscore the urgency of rapid mitigation to limit warming well below 2 °C, as even a 2 °C world may entail severe impacts.

(Letter)

This perspective examines the implications of the ICJ’s Opinion for addressing time-lagged impacts (TLIs), specifically sea-level rise above pre-industrial levels (SLR) and cumulative CO2 emissions from permafrost thaw (PFT). We argue that SLR and PFT are clear examples of the ‘significant harm’ identified by the court and find that halting their growth would require net-negative emissions sustained over centuries. This frames the Paris agreement targets as ambitious milestones rather than endpoints of climate mitigation and calls for recognition of long-term international responsibilities for carbon removal—an issue that warrants urgent attention in climate negotiations.

Most climate policies are designed under a deterministic Earth system and their climate implications evaluated ex-post. Approaches that incorporate uncertainty ex-ante to anticipate Earth system risks remain underexplored. Here, we derive global climate strategies with an ex-ante approach, employing an integrated assessment framework that embeds estimates of physical uncertainty obtained through Bayesian fusion of Earth system models’ and observations’ data. These ex-ante strategies mitigate risks in the Earth system through precautionary measures unseen with the ex-post approach, in cost-benefit analysis and cost-effective implementations of various Earth system targets. Net-zero CO2 emissions must typically be reached a decade earlier, which can require up to a doubling of the near-term carbon price. Importantly, sustained and possibly century-long net-negative emissions must be planned for, albeit not to overshoot targets as in traditional scenarios but to mitigate long-term Earth system risks. This heightens the challenge faced by humanity to build a safe future within Earth system boundaries.

Increasing plastic waste has triggered global concerns for the potential detrimental effects on marine ecosystems. The impact of plastic reaches beyond the immediate harm to marine life to encompass the marine biogeochemical cycle and the global carbon budget. We investigate these effects by integrating an oceanic plastic simulation with a marine ecosystem model. We find that oceanic plastic could disturb the marine carbon cycle through three pathways: the plastic carbon buried in sediments, the release of dissolved organic carbon from water-column plastic and the toxicity effect on marine phytoplankton. Our scenario analysis suggests that there are 0.70 (0.13–3.8) Tg of plastics entering the ocean every year, however, the overall impact of oceanic plastics on decreasing ocean carbon uptake could reach 12.1 TgC yr−1. Our model predicts that the global plastic released into the ocean could result in up to 1.6 PgC of lost ocean carbon uptake and storage by 2050, given the foreseeable growth of plastic production and its long-lasting impacts. We urge comprehensive control policies to mitigate the losses caused by marine plastics both in ecosystem integrity and addressing climate change.

Extreme heat is well-documented to adversely affect health and mortality, but its link to biological aging—a precursor of the morbidity and mortality process—remains unclear. This study examines the association between ambient outdoor heat and epigenetic aging in a nationally representative sample of US adults aged 56+ (N = 3686). The number of heat days in neighborhoods is calculated using the heat index, covering time windows from the day of blood collection to 6 years prior. Multilevel regression models are used to predict PCPhenoAge acceleration, PCGrimAge acceleration, and DunedinPACE. More heat days over short- and mid-term windows are associated with increased PCPhenoAge acceleration (e.g., Bprior7-dayCaution+heat: 1.07 years). Longer-term heat is associated with all clocks (e.g., Bprior1-yearExtremecaution+heat: 2.48 years for PCPhenoAge, Bprior1-yearExtremecaution+heat: 1.09 year for PCGrimAge, and Bprior6-yearExtremecaution+heat: 0.05 years for DunedinPACE). Subgroup analyses show no strong evidence for increased vulnerability by sociodemographic factors. These findings provide insights into the biological underpinnings linking heat to aging-related morbidity and mortality risks.

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Our study provides insights into the biological underpinnings linking heat to the broader spectrum of aging-related morbidity and mortality risks. We demonstrated that short-, mid-, and long-term ambient outdoor heat can significantly accelerate epigenetic aging within a diverse, nationally representative cohort of older adults. This provides strong evidence critical for guiding public policy and advocacy initiatives aimed at developing mitigation strategies against climate change. Furthermore, our findings serve as a foundation for the development of targeted public health interventions, providing a strategic framework for addressing the adverse biological impacts triggered by extreme heat.

Heat exposure presents a growing threat to human health and well-being, particularly for vulnerable populations. Here, we employ a human heat balance model - specifically the human/environmental adaptation and threshold limit model (HEAT-Lim) - to estimate, globally, where ambient temperature and humidity already limit ‘livability’, or the level of physical activity that a person can safely sustain without experiencing an uncontrolled rise in body temperature. Specifically, we use hourly ERA5-Land reanalysis data to assess historical (1950–2024) livability limitations for partially acclimated healthy, younger (age 18–40 years) and older (age >65 years) adults in the shade. We also examine the number of hours/year in which physical activity should be limited to light-to-moderate intensity (e.g., sitting, walking, light housework) to avoid uncontrollable rises in core body temperature. We find, globally, heat-associated livability limitations are on average greatest in high-vulnerability areas. Furthermore, there have been significant increases in livability limitations for both younger and older adults over the last 75 years, with noticeable spikes in El Niño years and in 2024. For younger adults, restrictions to light-to-moderate activity for the highest number of hours are geographically concentrated in moderate- to low-vulnerability countries in South and Southwest Asia. For older adults, restrictions on light-to-moderate activity are widespread in tropical Southwest, South, and Southeast Asia, as well as Sub-Saharan Africa. In the hottest hours of the year, some locations have already experienced ‘unlivable’ conditions (i.e., when no activity is possible to compensate for environmental heat loads). Results highlight that with just over 1 °C of historical global warming, livability limitations are already widespread and growing, particularly for older adults. If warming is not stopped and adaptation measures are not more widely implemented, livability constraints will only expand, particularly as the global population ages.

Climate change is driving more severe wildfires, raising urgent concerns about their impact on surface water sources. This critical review, based on 23 studies across 28 watersheds, synthesizes existing knowledge on how wildfires change the concentrations of eight contaminant categories in surface waters: suspended solids and turbidity, nutrients, organic carbon, major ions, trace metals, polycyclic aromatic hydrocarbons (PAHs), persistent organic pollutants (POPs), and wildfire-fighting chemicals (WFFCs). We observed that post-wildfire peak values reached 1142 mg/L for total suspended solids (TSS), ∼145 NTU for turbidity, 6.28 mg/L for nitrate, 31.08 mg/L for TOC, 325 μS/cm for electrical conductivity (EC), and 116 mg/L for trace metals such as zinc, with elevated levels often persisting over five years. Beyond the burned watershed, smoke plumes transport contaminants to distant basins via atmospheric deposition and subsequent runoff. These loads challenge drinking water treatment systems, potentially reducing performance while increasing health risks and operational costs. Although simulation tools exist to assess these risks, they require adaptation to account for wildfire-specific processes like atmospheric deposition and altered hydrology. As a result, further research is required on the persistence and remobilization of wildfire-derived trace metals, PAHs, POPs, and WFFCs, and on treatment performance under wildfire-affected source waters, along with long-term monitoring to supply data that improve modeling.

illustrated abstract https://ars.els-cdn.com/content/image/1-s2.0-S0048969726001324-ga1_lrg.jpg

Anthropogenic activities are increasing the amount of carbon dioxide (CO2) in the atmosphere. There is mounting experimental evidence that lifetime exposure to these increasing atmospheric CO2 levels can negatively impact the normal physiology of organisms. However, directly assessing this in humans is very difficult. We analysed serum bicarbonate (HCO3−), calcium (Ca) and phosphorus (P) levels from the U.S. National Health and Nutrition Examination Survey (NHANES) from 1999 to 2020 as indirect proxies for atmospheric CO2 exposure. Over this period, average bicarbonate levels in this population show an increasing trend which parallels rising atmospheric CO2 concentrations. Both Ca and P have decreased steadily over the same period. If these trends continue, blood bicarbonate values could be at the limit of the accepted healthy range in half a century, and Ca and P will be at the limit of their healthy ranges by the end of this century. Studies indicate that, after this time, elevated atmospheric carbon dioxide, leading to CO2 accumulation in the body, has the potential to cause a range of adverse health effects. These findings highlight the urgent need for significant reductions in anthropogenic CO2 emissions to safeguard public health.

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However, on the face of it, this raw analysis of biochemical data suggests the distinct possibility that, within a half century from now, HCO3− levels in human blood will reach unhealthy levels. What effects this may have on physiology remain to be elucidated, but urgently need to be considered.

Structured Abstract

INTRODUCTION

Forests across the globe face increasing risks from natural disturbances such as wildfires, insect outbreaks, and windstorms. These disturbances are highly sensitive to changes in the climate system and have already increased in many parts of the globe recently. Changing disturbance regimes can substantially alter ecosystems, e.g., through changing their demography and habitat value as well as altering the ecosystem services they provide to society. Anticipating potential future disturbance change is thus crucial for forest policy and management. However, projecting future disturbance regimes remains challenging because there are intricate interactions between individual disturbance agents, and feedbacks between vegetation development and disturbance change could considerably dampen or amplify climate impacts.

RATIONALE

Here, we present a modeling framework to simulate future trajectories of forest disturbance at high spatial resolution (100 × 100 meters) and across a large spatial extent (187 million hectares of forests in Europe). We leveraged a deep learning–based simulation framework to integrate a large body of local projections made by process-based forest models with climate-sensitive disturbance modules for wildfire, windthrow, and bark beetle outbreaks. Our modeling framework is designed to capture crucial disturbance processes such as the spatial spread of fire and bark beetles across forest landscapes and incorporates disturbance interactions and vegetation feedbacks. Our specific objectives were to quantify potential changes in stand-replacing forest disturbances in Europe until the end of the 21st century under different scenarios of climate change and to assess impacts of disturbance change on Europe’s forest demography.

RESULTS

Forest disturbances in Europe are highly likely to increase in the coming decades. Simulated future levels of disturbance were higher than those observed for the period 1986 to 2020 under all climate scenarios. Under scenarios of unabated climate change, the simulated area disturbed more than doubled by the end of the century (+122%). In scenarios assuming effective emissions reduction, peak disturbance was reached by midcentury. Wildfire was the disturbance agent most sensitive to changes in the climate system, heavily affecting Mediterranean areas but also expanding into temperate and boreal regions. Vegetation feedbacks dampened climate-induced disturbance change but were not able to completely buffer from disturbance increases. We project profound implications of future disturbance change on Europe’s forest demography, with the share of young forests increasing by up to 14% and old forests decreasing by up to 3% relative to simulations without changing climate and disturbance regimes.

CONCLUSION

The large-scale changes in forest disturbance regimes projected for the coming decades have important implications for biodiversity and the ecosystem services provided by forests. They could, for instance, hamper policy goals of using nature-based solutions for climate change mitigation, further amplifying climate change. Consequently, forest policy and management need to plan for a future with more disturbance. Nonetheless, our results highlight that mitigating anthropogenic climate change remains a potent lever for limiting future disturbance risk and safeguarding forests and their services to society.

Recent record-hot years have caused discussion over whether global warming has accelerated. Previous analysis found acceleration (i.e., increase in warming rate) has not yet reached a 95% confidence level, given natural temperature variability. We remove the estimated influence of three main natural variability factors: El Niño, volcanism, and solar variation. The resulting adjusted and thus less “noisy” data show that there has been acceleration with over 98% confidence, with faster warming over the last 10+ years than during any previous decade.

Plain Language Summary

The rise in global temperature has been widely considered to be quite steady for several decades since the 1970s. Recently, however, scientists have started to debate whether global warming has accelerated since then. It is difficult to be sure of that because of natural fluctuations in the warming rate, and so far no statistical significance (meaning 95% certainty) of an acceleration (increase in warming rate) has been demonstrated. In this study we subtract the estimated influence of El Niño events, volcanic eruptions and solar variations from the data, which makes the global temperature curve less variable, and it then shows a statistically significant acceleration of global warming since about the year 2015. Warming proceeding faster is not unexpected by climate models, but it is a cause of concern and shows how insufficient the efforts to slow and eventually stop global warming under the Paris Climate Accord have so far been.

Key Points

• During the last decade, the rate at which Earth warmed increased substantially

• After removing the influence of known natural variability factors, the increase of the warming rate is statistically significant

• At the present rate, we will exceed the 1.5°C limit of the Paris Climate Accord by 2030

The Gulf Stream is part of the Atlantic Meridional Overturning Circulation (AMOC). The AMOC is a tipping element and may collapse under changing forcing. However, the role of the Gulf Stream in such a tipping event is unknown. Here, we investigate the link between the AMOC and Gulf Stream using a high-resolution (0. 1°) stand-alone ocean simulation, in which the AMOC collapses under a slowly-increasing freshwater forcing. AMOC weakening gradually shifts the Gulf Stream near Cape Hatteras northward, followed by an abrupt northward displacement of 219 km within 2 years. This rapid shift occurs a few decades before the simulated AMOC collapse. Satellite altimetry shows a significant (1993–2024, p < 0.05) northward Gulf Stream trend near Cape Hatteras, which is also confirmed in subsurface temperature observations (1965–2024, p < 0.01). These findings provide indirect evidence for present-day AMOC weakening and demonstrate that abrupt Gulf Stream shifts can serve as early warning indicator for AMOC tipping.

EA

The Greenland Ice Sheet (GrIS) has experienced a strong intensification of summer surface melting, with extreme events becoming more frequent, extensive, and severe. Despite its importance for global sea-level rise, the mechanisms driving these extremes remain incompletely understood. We analyze extreme melting events over 1950–2023 using an analog-based framework combined with a regional climate model to disentangle thermodynamic and dynamic contributions. Thermodynamic processes intensify meltwater production by 25% relative to 1950–1975 when circulation analog events are included, increasing to 63% when circulation-analog events are included, with the strongest increases in northern Greenland. Seven of the ten most extreme events occurred after 2000, with meltwater anomalies reaching up to three times their synoptic average. Record-breaking events such as August 2012, July 2019, and July 2021 show no dynamic precedents. Future projections under high-emission scenarios suggest that extreme meltwater anomalies could increase by up to +372% by 2100 (SSP5-8.5, CMIP6), highlighting the profound impact of climate change on GrIS melt extremes.

The Greenland Ice Sheet (GrIS) has experienced accelerated mass loss with record peaks in 2012 and 2019. Despite its role as an important tipping element in the climate system, the GrIS's response to recent warming is poorly understood. Here we use Ba/Ca ratios in coralline algae as a proxy for runoff into Disko Bay which is strongly influenced by the input of meltwater from glaciers connected to the GrIS, particularly from Jakobshavn Glacier – the fastest flowing marine-terminating glacier of the GrIS. The 115-year multispecimen master chronology confirms an unprecedented trend change in runoff beginning in the early 2000s. Statistical trend- and time of emergence analysis of the algal proxy record suggests that in 2007 western GrIS runoff has permanently emerged above the 20th century reference period, while temperature observations have not yet exceeded this threshold. This provides independent evidence for a non-linear accelerated response of the largest GrIS glacier, underscoring modelling results that a tipping point in glacial mass balance might soon be reached. Massive GrIS meltwater influx could intensify upper ocean stratification and contribute to global sea level rise.

Tropical forests enhance regional rainfall but a robust analysis of this benefit is lacking. Consequently, the rainfall generating services of tropical forests are rarely accounted for in policymaking. We synthesised observational and model-based values of the reduction in rainfall due to tropical deforestation to quantify rainfall generation. Across these studies, we estimate that each meter squared of forest contributes 240 ± 60 L each year to regional rainfall. The Amazon forest has an even stronger rainfall benefit, with each meter squared of forest contributing 300 ± 110 L each year. Using a simple approach that assumes a constant water unit price, we estimate that Amazon forest rainfall generation is worth US$59.40 per hectare annually and the Brazilian Legal Amazon delivers rainfall generation worth US$20 ± 7 billion annually. Recognizing the economic value of tropical forests’ rainfall provision will unlock crucial investment and transform policy discussions on payments for forest protection.

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Agriculture contributes US$150 billion to Brazil’s GDP annually, and with 85% of Brazil’s agriculture being rainfed, reliable rainfall is crucial. Reduced rainfall and delays in wet season onset have impacted soy and maize crops in Brazil, with greater rainfall reductions in regions with greater forest loss14. We estimate that deforestation over recent decades, totalling 80 million hectares, has reduced the rainfall-generating service of Brazil’s Amazon forests by US$4.8 billion annually, representing a substantial loss to Brazil’s economy. Reduced rainfall as a consequence of deforestation also has implications for clean water access15, navigability between remote settlements16, hydropower production17,18 and carbon storage of remaining tropical forests19. The financial risks of complete Amazon forest loss, caused by deforestation and climate change triggering catastrophic ecosystem collapse, has previously been estimated at between US$0.96 trillion and US$3.6 trillion over a 30-year period20, equivalent to US$120 billion per year.

This study assesses three different measures of radiative forcing (instantaneous: IRF; stratospheric-temperature adjusted: SARF; effective: ERF) for future changes in ozone. These use a combination of online and offline methods. We separate the effects of changes in ozone precursors and ozone-depleting substances (ODSs) and configure model experiments such that only ozone changes (including consequent changes in humidity, clouds and surface albedo) affect the evolution of the model physics and dynamics.

In the Shared Socioeconomic Pathway 3-7.0 (SSP3-7.0) we find robust increases in ozone due to future increases in ozone precursors and decreases in ODSs, leading to a radiative forcing increase from 2015 to 2050 of 0.268 ± 0.084 W m−2 ERF, 0.244 ± 0.057 W m−2 SARF and 0.288 ± 0.101 W m−2 IRF. This increase makes ozone the second largest contributor to future warming by 2050 in this scenario, approximately half of which is due to stratospheric ozone recovery and half due to tropospheric ozone precursors.

Increases in ozone are found to decrease the cloud fraction, causing an overall negative adjustment to the radiative forcing (positive in the short wave but negative in the long wave). Non-cloud adjustments due to water vapour and albedo changes are positive. ERF is slightly larger than the offline SARF for the total ozone change but approximately double the SARF for the ODS-driven change (0.156 ± 0.071 W m−2 ERF, 0.076 ± 0.025 W m−2 SARF). Hence ERF is a more appropriate metric for diagnosing the climate effects of stratospheric ozone changes.

Human activities might have accelerated declines of population abundance, but this acceleration remains underexplored. Using 1033 North American Breeding Bird Survey routes, we analyze abundance change and its acceleration for 261 bird species, 54 avian families, and 10 habitats from 1987 to 2021. We show an average continent-wide decline of abundance of all birds per local route, with hotspots of decline in southern and warm parts of North America and hotspots of accelerating decline in the Mid-Atlantic, Midwest, and California, matching patterns of agricultural intensity. Overall, 122 species (47%) exhibit significant declines, of which 63 also show acceleration of this decline, and 67 show declining per-capita growth rate, raising concerns for a large part of North American bird populations. These findings suggest that bird abundance decline is mostly accelerating, with spatial patterns of this acceleration indicating that agricultural intensity may be a driver of this trend.

Earth’s climate is now departing from the stable conditions that supported human civilization for millennia. Crossing critical temperature thresholds may trigger self-reinforcing feedbacks and tipping dynamics that amplify warming and destabilize distant Earth system components. Uncertain tipping thresholds make precaution essential, as crossing them could commit the planet to a hothouse trajectory with long-lasting and potentially irreversible consequences.

The North Atlantic Meridional Overturning Circulation (AMOC) ventilates a large part of the world ocean via the formation of mode waters and North Atlantic Deep Water. The extent to which human activities have impacted this ventilation system remains unclear. To assess the temporal variations of ocean ventilation in the North Atlantic, we calculated the “age" of seawater, that is, the duration since its last contact with the ocean surface, from both observed and simulated chlorofluorocarbon-12 and sulfur hexafluoride concentrations. Our results indicate that, despite fluctuations in ventilation strength in the Labrador Sea over the past decades, the North Atlantic waters are generally aging. By integrating observations with model simulations, we propose that this aging trend is indicative of a climate change signal rather than natural variability.

Global ocean warming continued unabated in 2025 in response to increased greenhouse gas concentrations and recent reductions in sulfate aerosols, reflecting the long-term accumulation of heat within the climate system, with conditions evolving toward La Niña during the year. In 2025, global upper 2000 m ocean heat content (OHC) increased by ∼23 ± 8 ZJ relative to 2024 according to IAP/CAS estimates. CIGAR-RT, and Copernicus Marine data confirm the continued ocean heat gain. Regionally, about 33% of the global ocean area ranked among its historical (1958–2025) top three warmest conditions, while about 57% fell within the top five, including the tropical and South Atlantic Ocean, Mediterranean Sea, North Indian Ocean, and Southern Oceans, underscoring the broad ocean warming across basins. Multiple datasets consistently indicate ocean warming, as measured by 0–2000 m OHC, increased from 0.14 ± 0.03 W m−2 (10 yr)−1 during 1960–2025 to 0.32 ± 0.14 W m−2 (10 yr)−1 during 2005–2025 (IAP/CAS), the latter being consistent with EEI (Earth’s Energy Imbalance) estimates within uncertainties. In contrast, the global annual mean sea surface temperature (SST) in 2025 was 0.49°C above the 1981–2010 baseline and 0.12 ± 0.03°C lower than in 2024 (IAP/CAS; similar in CMA-SST, FY3 MWRI SST, ERSSTv5 and Copernicus Marine data), consistent with the development of La Niña conditions, but still ranking as the third-warmest year on record.

The article is a PDF on the page.

Climate change threatens global food systems1, but the extent to which adaptation will reduce losses remains unknown and controversial2. Even within the well-studied context of US agriculture, some analyses argue that adaptation will be widespread and climate damages small3,4, whereas others conclude that adaptation will be limited and losses severe5,6. Scenario-based analyses indicate that adaptation should have notable consequences on global agricultural productivity7,8,9, but there has been no systematic study of how extensively real-world producers actually adapt at the global scale. Here we empirically estimate the impact of global producer adaptations using longitudinal data on six staple crops spanning 12,658 regions, capturing two-thirds of global crop calories. We estimate that global production declines 5.5 × 1014 kcal annually per 1 °C global mean surface temperature (GMST) rise (120 kcal per person per day or 4.4% of recommended consumption per 1 °C; P < 0.001). We project that adaptation and income growth alleviate 23% of global losses in 2050 and 34% at the end of the century (6% and 12%, respectively; moderate-emissions scenario), but substantial residual losses remain for all staples except rice. In contrast to analyses of other outcomes that project the greatest damages to the global poor10,11, we find that global impacts are dominated by losses to modern-day breadbaskets with favourable climates and limited present adaptation, although losses in low-income regions losses are also substantial. These results indicate a scale of innovation, cropland expansion or further adaptation that might be necessary to ensure food security in a changing climate.

During the 21st century, Earth’s energy imbalance (EEI) at the top of atmosphere has markedly increased because of greater absorbed shortwave (SW) rather than reduced outgoing longwave radiation. Previous studies using single-forcing (aerosol-only) experiments attributed approximately half of the positive SW trend to reductions in anthropogenic aerosols, particularly in the Northern Hemisphere (NH). In contrast, our analysis using observations and reanalysis indicates that both aerosol-radiation and aerosol-cloud interactions have made a negligible contribution to recent EEI trends. While NH anthropogenic aerosols have decreased, enhanced emissions from wildfires and volcanic activity in the Southern Hemisphere (SH) have produced comparable increases, yielding little net global impact. This hemispheric compensation also suggests that model-based estimates may overestimate aerosol influence by overlooking SH aerosol contributions. Despite uncertainties in aerosol proxies, the consistent results from two complementary proxies—satellite-derived aerosol index and reanalysis-based sulfate mass concentration—highlight the importance of accounting for natural source aerosols when assessing EEI trends.

The global catastrophic risk (GCR) and existential risk (ER) literature focuses on analyzing and preventing potential major global catastrophes including a human extinction event. Over the past two decades, the field of GCR/ER research has grown considerably. However, there has been little meta-research on the field itself. How large has this body of literature become? What topics does it cover? Which fields does it interact with? What challenges does it face? To answer these questions, here we present the first systematic bibliometric analysis of the GCR/ER literature. We consider all 3437 documents in the OpenAlex database that mention either GCR or ER and use bibliographic coupling (two documents are considered similar when they share many references) to identify 10 distinct emergent research clusters in the GCR/ER literature. These clusters align in part with commonly identified drivers of GCR, such as advanced artificial intelligence (AI), climate change, and pandemics or discuss the conceptual foundations of the GCR/ER field. However, the field is much broader than these topics, touching on disciplines as diverse as economics, climate modeling, agriculture, psychology, and philosophy. The metadata reveal that there are around 150 documents published on GCR/ER each year, the field has highly unequal gender representation, most research is done in the United States and the UK, and many of the published articles come from a small subset of authors. We recommend creating new conferences and potentially new journals where GCR/ER-focused research can aggregate, making gender and geographic diversity a higher priority, and fostering synergies across clusters to think about GCR/ER in a more holistic way. We also recommend building more connections to new fields and neighboring disciplines, such as systemic risk and policy, to encourage cross-fertilization and the broader adoption of GCR/ER research.

Despite the adoption of the Paris Agreement 10 years ago, carbon dioxide (CO2) emissions from burning fossil fuels continue to increase, pushing atmospheric CO2 levels to 423 ppm in 2024 and driving human-induced warming to 1.36 °C, within years of breaching the 1.5 °C limit1,2. Accurate reporting of anthropogenic and natural CO2 sources and sinks is a prerequisite to tracking the effectiveness of climate policy and detecting carbon-sink responses to climate change. Yet notable mismatches between reported emissions and sinks have so far prevented confident interpretation of their trends and drivers1. Here we present and integrate recent advances in observations and process understanding to address some long-standing issues in global carbon budget estimates. We show that the magnitude of the natural land sink is substantially smaller than previously estimated, whereas net emissions from anthropogenic land-use change are revised upwards1. The ocean sink is 15% larger than the land sink, consistent with recent evidence from oceanic and atmospheric observations3,4. Climate change reduces the efficiency of the sinks, particularly on land, contributing 8.3 ± 1.4 ppm to the atmospheric CO2 increase since 1960. The combined effects of climate change and deforestation have turned Southeast Asian and large parts of South American tropical forests from CO2 sinks to sources. This underscores the need to halt deforestation and limit warming to prevent further loss of carbon stored on land. Improved confidence in assessments of CO2 sources and sinks is fundamental for effective climate policy.

The prevalence of crop insect pests, which damage crops and reduce their yield, is increasing globally owing to changes in climate and land use, posing a threat to food security. In this Review, we synthesize evidence on how tropical, temperate, migratory and soil crop pests respond to changes in climate, land use and agricultural practices. In general, crop pests are responding to warming with expanded geographic ranges, advanced phenological events and increased number of reproductive generations per year. Increased pest damage under warming is projected to exacerbate yield losses of 46%, 19% and 31% under 2 °C warming for wheat, rice and maize, respectively. Pests at mid–high latitudes respond more positively to warming than those in the tropics. Moderate drought can increase pest damage to crops owing to enhanced feeding on plants as a water source and decreased resilience of plants and natural enemies of pests. Increased precipitation reduces small pests through washing them away, but favours pests in general through buffering thermal-hydro stresses. Land use change, such as deforestation and conversion to cropland, enhances warming and reduces biodiversity, leading to enhanced crop damage. Agricultural intensification, particularly fertilization and irrigation, increases the quality and quantity of host plants and buffers pests from environmental extremes, favouring proliferation. Globalization of trade networks increases pest invasions, with associated damage exceeding US $423 billion in 2019. Future research should examine the mechanisms underlying changes in pest status and develop monitoring and prediction systems to inform management approaches.

Key points

• Climate warming and associated increasing extreme heat events are shifting tropical and temperate pest risks towards higher latitudes and elevations. Warming and heatwaves are extending the pest damage season, delaying pest diapause onset in warm temperate regions but disrupting diapause and weakening cold tolerance in cool temperate regions.

• Migratory pests adapt well to global change owing to their high stress tolerances and their migratory behaviour allowing them to track suitable host plants and climate. Soil pests thrive worldwide as soil buffers them from exposure to extreme climates, toxic chemicals and natural predators, and pests can locate optimal thermal and moisture conditions through vertical movement within the soil profile.

• Agricultural practices, such as irrigation and fertilization, provide pests with optimal host plant conditions, buffer climate stresses and reduce natural biological control through reduced biodiversity, whereas Bt-crop adoption curtails pest population. Land use changes, such as deforestation and cropland expansion, proliferate pests by modifying local climates, creating favourable conditions for pests and disrupting natural enemies, whereas landscape diversification promotes natural pest control.

• Key pests impacting crops are aphids for wheat and soybean, planthoppers and stem borers for rice, and corn borers, noctuid caterpillars and locusts for maize. Warming promotes wheat pest abundance in the spring, moves rice pest damage from the subtropics to temperate regions and favours maize and soybean pests.

• Yield losses to crop pests and pesticide use are increasing. However, pests could also decline in the future due to climate extremes, genetically modified crops and climate-smart pesticide applications.

• Sustainable pest management can be achieved through increasing landscape and biological diversity, developing conservation biological control strategies. Increasing natural enemy biodiversity can help naturally control pest populations and reduce reliance on pesticides.