Recent uciess items

Persistence and turnover of soil organic carbon in global drylands.

Mon, 27 Apr 2026 00:00:00 +0000

Reliable predictions of dryland carbon fluxes require understanding the persistence and turnover of soil organic carbon (SOC). We measure radiocarbon to quantify the age of SOC and CO₂ released from soil respiration at 97 dryland sites across six continents. Here we show that bulk SOC contains little C fixed in the past 60 years, while respired CO₂ originates from both bomb-derived recent C and millennia-old C, challenging the idea that old C is chemically or physically protected. Radiocarbon suggests mean ages of ~2100 years for bulk SOC and ~520 years for respired CO₂, the latter far older than machine-learning (<50 years) or Earth system models predict. Aridity, net primary productivity, and SOC content are dominant predictors for radiocarbon signatures, with abrupt shifts to older C beyond an aridity threshold of ~0.87. Our findings underscore the need to incorporate the vulnerability of older carbon into models and land management strategies.

Widespread windthrow in Southeast Asian tropical forests verified by satellite observations

Tue, 31 Mar 2026 00:00:00 +0000

Windthrow, defined as abrupt tree mortality caused by intense winds, is well documented in the Neotropics but remains largely unverified in Asian tropical forests. Using Landsat 8 imagery for the period 2020-2022 and established spectral (shortwave-infrared, near-infrared, and red band composites) and morphological criteria (fan-shaped geometry and sharp boundaries), this study verified the presence of windthrow across Sumatra, Borneo, and New Guinea and produced the first georeferenced inventory of 60 events in the region. Event sizes were right-skewed, with many small gaps and few large (>200 ha) disturbances. Orientations were anisotropic, with concentrations of windthrow events pointing west to northwest-to-north and eastward, both aligning with known pathways of organized convection in the Maritime Continent of Southeast Asia. Detection was conservatively biased low by cloud cover, long revisit intervals, and the exclusion of land-use areas. This study provides a verified...

Mortality correlates with tree functional traits across a wood density gradient in the Central Amazon

Wed, 18 Mar 2026 00:00:00 +0000

Introduction: Understanding the mechanisms of tree mortality in tropical ecosystems remains challenging, in part due to the high diversity of tree species and the inherently stochastic nature of mortality. Plant functional traits offer a mechanistic link between plant physiology and performance, yet their ability to predict growth and mortality remains poorly understood. Given recent increases in tree mortality rates in the Amazon forest following extreme drought and wind events, we tested if lower wood density and acquisitive plant functional traits were associated with increased growth and mortality for common co-occurring trees in the Central Amazon. Methods: Seventeen trees of different species with similar sizes but a range in wood density (WD) and wood traits were felled, then assessed for 27 different individual functional parameters, including whole tree architecture, stem xylem anatomical and hydraulic traits and leaf traits. Traits of the individual trees were related...

Representing lateral groundwater flow from land to river in Earth system models

Mon, 16 Mar 2026 00:00:00 +0000

Abstract. Lateral groundwater flow (LGF) is an important hydrologic process in controlling water table dynamics. Due to the relatively coarse spatial resolutions of land surface models, the representation of this process is often overlooked or overly simplified. In this study, we developed a hillslope-based lateral groundwater flow model. Specifically, we first developed a hillslope definition model based on an existing watershed delineation model to represent the subgrid spatial variability in topography. Building upon this hillslope definition, we then developed a physical-based lateral groundwater flow using Darcy’s equation. This model explicitly considers the relationships between the groundwater table along the hillslope and the river water table levels. We coupled this intra-grid model to the land component (E3SM Land Model: ELM) and river component (MOdel for Scale Adaptive River Transport: MOSART) of the Energy Exascale Earth System Model (E3SM). We tested both the hillslope...

Widespread forest disturbance from windthrow in central African rainforests

Thu, 12 Mar 2026 00:00:00 +0000

Natural disturbances are major drivers of tropical forest dynamics, yet their role in Central Africa’s old-growth rainforests, the world’s second largest tropical forest block, remains poorly quantified. Here we present the first regional assessment of windthrow, the uprooting or breakage of trees by wind. Using Landsat imagery from 2019 to 2020, we detected 74 windthrow events ≥30 ha, collectively affecting ~18,600 ha. These events were concentrated in eastern regions where mesoscale convective systems and extreme rainfall are most frequent. Sizes of windthrow events followed a Weibull distribution, with a single 3974 ha event accounting for one fifth of the total affected area. Event orientations aligned with prevailing storm outflows, and their timing coincided with peaks in extreme rainfall. For a subset of seven events with adequate temporal coverage before and after disturbance, near-infrared reflectance returned to pre-disturbance levels within months, indicating a rapid...

Radiative, Hydrologic, and Circulation Responses to Warming in Cess‐Potter Simulations Using the Global 3.25‐km SCREAM

Tue, 10 Mar 2026 00:00:00 +0000

Abstract Using the global 3.25‐km Simple Cloud Resolving E3SM Atmosphere Model (SCREAM 3 km), a pair of 13‐month Cess‐Potter simulations are performed to quantify the radiative feedbacks and the hydrologic and circulation responses to warming. Large‐scale aspects of SCREAM 3 km's top‐of‐atmosphere radiative fluxes, precipitation rates, and circulations are in good agreement with observations and reanalysis, with notable differences, including a drier lower free‐troposphere in the Tropics, reduced precipitation and humidity over the Tropical West Pacific, and poleward shifted Southern Hemisphere midlatitude jet. In response to warming, SCREAM 3 km predicts a total radiative feedback within the top 15% of the CMIP5 and CMIP6 models, which puts it substantially higher than the feedback reported by other kilometer‐scale models. SCREAM 3 km's high radiative feedback stems from a strongly positive shortwave cloud feedback, most prominent over the mid‐ and high‐latitudes....

The Role of Canopy Turbulence in Wildland Fire Behavior

Wed, 4 Mar 2026 00:00:00 +0000

Characterizing the physical and dynamic meteorology of wildland fires has obvious socioeconomic importance and is necessary to develop not only firefighting but also mitigation strategies such as prescribed burns and effective fuel management practices such as forest thinning. However, despite significant progress over a century, there are shortcomings in our understanding of the physical processes governing wildland fire behavior. Although some research progress has been made in understanding how fires spread on grasslands, several aspects of fire behavior within the forest canopy environment are still not well-understood. This review is an attempt to organize the fluid mechanics of the mass, momentum, and energy transfer during wildland fire events through the lens of vegetation canopy turbulence. The structure, organization, and progress of the flame front and the buoyant plume through the canopy are shown to be intricately related to the coherent structures associated with...

Transboundary water conflicts, cooperation, and pathways forward

Wed, 25 Feb 2026 00:00:00 +0000

Transboundary water conflicts, cooperation, and pathways forward

Evolving approaches and data availability for understanding the impact of land-use change on ecosystem services

Wed, 25 Feb 2026 00:00:00 +0000

Understanding how land-use change alters the flow of ecosystem services is critical for sustainability policy and planning. We conducted a systematic review of 459 peer-reviewed articles published between 2001 and March 2024 to (a) catalogue which ecosystem services have been studied and their geographic distribution, (b) trace methodological innovations in mapping, and (c) assess the integration of emerging data streams. Our analysis identified 23 ecosystem services spanning provisioning (food, water, raw materials), regulating (climate regulation, erosion control, flood protection), and cultural (recreation, aesthetics), with provisioning services most often mapped individually but regulating services dominating in category-level assessments. Regionally, Asia (especially China) contributed over half (51 %) of the case studies, while case studies in Europe, Africa, and the Americas are also increasing, aided by international collaborations in nearly 30 % of the studies....

Transcriptomic, physiological, and biochemical responses of turmeric (Curcuma longa) to heat stress

Wed, 11 Feb 2026 00:00:00 +0000

Turmeric (Curcuma longa) is an economically important crop native to hot and humid regions of India. The current study aims to establish the basis for a multifaceted understanding of turmeric plants’ cellular and physiological responses to heat stress. We combined transcriptomic (RNA-seq) analysis, real-time photosynthesis data, and profiles of emissions of biogenic volatile organic compounds (BVOCs) to interpret the responses of turmeric plants to heat stress. RNAseq data indicated significant differential expression in 41.8% of genes, with photosynthesis-related genes overrepresented. Photosynthetic rate measurements demonstrated an almost complete failure of photosynthesis at 41 °C, followed by incomplete recovery at a normal temperature of 21 °C. Emissions of almost all detected BVOCs increased considerably during periods of heat treatment. The data establishes the ontological gene groups most affected, estimates the temperature tolerance of turmeric, and provides insights...

Gene duplication, horizontal gene transfer, and trait trade-offs drive evolution of postfire resource acquisition in pyrophilous fungi.

Thu, 15 Jan 2026 00:00:00 +0000

Wildfires significantly alter soil carbon (C) and nitrogen (N), reducing microbial richness and biomass, while selecting for "fire-loving" pyrophilous microbes that drive postfire nutrient cycling. However, the genomic strategies and functional trade-offs (balancing gains in one trait with costs in another) underlying the traits that enable pyrophilous microbes to survive and thrive postfire are virtually unknown. We hypothesized that pyrophilous fungi employ specialized genomic adaptations for C and N cycling, with evolutionary trade-offs between traits governing aromatic C degradation, N acquisition pathways, and rapid growth. To test these hypotheses, we performed complementary comparative genomics, transcriptomics after pyrogenic organic matter amendment, and growth rate bioassays for 18 pyrophilous fungi from five Ascomycota (Eurotiales, Pleosporales, Sordariales, Coniochaetales, and Pezizales) and three Basidiomycota (Agaricales, Holtermanniales, and Geminibasidiales) orders...

Implementation and Evaluation of Emission‐Driven Land‐Atmosphere Coupled Simulation in E3SMv2.1

Mon, 12 Jan 2026 00:00:00 +0000

Abstract Emissions‐driven (prognostic CO 2 ) simulations are essential for representing two‐way carbon‐climate feedback in Earth System Models. We present an emissions‐driven land–atmosphere coupled biogeochemistry (BGC) configuration (BGCLNDATM_progCO2) in version 2.1 of the Energy Exascale Earth System Model (E3SMv2.1). This is the first E3SM configuration that performs land‐atmosphere emission‐hindcasts. Here, we document its implementation, evaluate the model's performance against observations and other models, and propose a structured evaluation protocol for such emissions‐driven simulations. We conducted transient historical simulations (1850–2014) with BGCLNDATM_progCO2 and compare them to reference simulations—a land‐atmosphere coupled simulation without BGC and a standalone land simulation with BGC, both using prescribed CO 2 concentrations—and to observations. BGCLNDATM_progCO2 overestimates atmospheric CO 2 concentrations by 11–23 ppm yet stays within the 40‐ppm...

Multi-ignition fire complexes drive extreme fire years and impacts

Tue, 6 Jan 2026 00:00:00 +0000

Climate change is intensifying fire behavior, with the largest and fastest-spreading fires causing the greatest impacts on people and ecosystems. Yet the mechanisms driving variability and trends in large fires remain poorly understood. Using 12-hour satellite-derived fire tracking data from 2012 to 2023, we show that the merging of separate ignitions into multi-ignition complexes is a key process amplifying fire size and destructive potential across temperate and boreal ecoregions. Multi-ignition fires account for 31% of the burned area in California and 59% in the Arctic-boreal domain, spread faster and persist longer than single-ignition fires, and disproportionately contribute to extreme fire years in California, Canada, and Siberia. They also generate stronger atmospheric feedbacks, produce more pyrocumulonimbus events, and strain firefighting capacity by dispersing suppression resources. Recognizing and accounting for fire-merging dynamics are critical for improving wildfire...

Large role of anthropogenic climate change in driving smoke concentrations across the western United States from 1992 to 2020

Sat, 20 Dec 2025 00:00:00 +0000

Wildfire activity has increased dramatically in the western United States over the last three decades, having a significant impact on air quality and human health. However, quantifying the drivers of trends in wildfires and subsequent smoke concentrations is challenging, as both natural variability (NV) and anthropogenic climate change (ACC) play important roles. Here, we devise an approach involving observed meteorology and vegetation and a range of models to determine the relative roles of ACC and NV in driving burned area across the western United States. We also examine the influence of ACC on smoke concentrations. We estimate that ACC accounts for 33 to 82% of observed total burned area, depending on the ecoregion, yielding 65% of total fire emissions on average across the western United States from 1992 to 2020. In all ecoregions except Mediterranean California, ACC contributes to a greater percentage of burned area in lightning-ignited wildfires than in human-ignited wildfires....

Atmospheric Feedbacks Reverse the Sensitivity of Modeled Photosynthesis to Stomatal Function

Wed, 17 Dec 2025 00:00:00 +0000

Abstract Stomata mediate fluxes of carbon and water between terrestrial plants and the atmosphere. These fluxes are governed by stomatal function and can be modulated in many Earth system models by an empirical parameter within the calculation of stomatal conductance, the stomatal slope . Intuitively, represents the marginal water cost of carbon, relating it to the emergent plant property of water use efficiency. Observations show that can range widely across and within plant types in varying environments, and this distribution of is not captured within Earth system models which represent each plant type with a single value. Here we examine how influences photosynthesis using coupled Earth system model simulations by perturbing to observed and percentiles for each plant type. We find that high reduces photosynthesis nearly everywhere, while low has regionally dependent responses. Under fixed atmospheric conditions, low increases photosynthesis in the Amazon and central North America...

Implementation of solar UV and energetic particle precipitation within the LINOZ scheme in ICON-ART

Wed, 19 Nov 2025 00:00:00 +0000

Abstract. We extended the Linearized ozone scheme – LINOZ in the ICON (ICOsahedral Nonhydrostatic) – ART (the extension for Aerosols and Reactive Trace gases) model system to include NOy formed by auroral and medium-energy electrons in the upper mesosphere and lower thermosphere, and the corresponding ozone loss, as well as changes in the rate of ozone formation due to the variability of the solar radiation in the ultraviolet wavelength range. This extension allows us to realistically represent variable solar and geomagnetic forcing in the middle atmosphere using a very simple ozone scheme. The LINOZ scheme is computationally very cheap compared to a full middle atmosphere chemistry scheme, yet provides realistic ozone fields consistent with the stratospheric circulation and temperatures, and can thus be used in climate models instead of prescribed ozone climatologies. To include the reactive nitrogen (NOy) produced by auroral and radiation belt electron precipitation in...

Interactive Gas Chemistry for Enhanced Science Capabilities of the Energy Exascale Earth System Model Version 3

Sat, 8 Nov 2025 00:00:00 +0000

Abstract Atmospheric chemistry plays a crucial role in Earth system models (ESMs), controlling atmospheric composition and radiative balance; it is highly interactive with the physical climate, biogeochemical cycles, and human systems. However, it often imposes computational challenges in an ESM. Here we develop a full troposphere‐stratosphere interactive chemistry module for the US Department of Energy's Energy Exascale Earth System Model (E3SM). We intentionally build a streamlined module based on E3SM version 2 that interacts with other components and maintains all of major chemical and chemistry‐climate feedbacks. The module incorporates a new, highly efficient tracer advection scheme; linearization of stratospheric chemistry; and abridged tropospheric chemical mechanism with 28 reactive tracers. This new model, E3SM‐chem, can readily perform century‐long climate simulations of ozone, methane, and nitrous oxide based on emission scenarios as well as provide hourly budgets...

Near-term Climate Change: Projections and Predictability

Sat, 8 Nov 2025 00:00:00 +0000

Executive Summary This chapter assesses the scientific literature describing expectations for near-term climate (present through mid-century). Unless otherwise stated, ‘near-term’ change and the projected changes below are for the period 2016–2035 relative to the reference period 1986–2005. Atmospheric composition (apart from CO2; see Chapter 12) and air quality projections through to 2100 are also assessed. Decadal Prediction The nonlinear and chaotic nature of the climate system imposes natual limits on the extent to which skilful predictions of climate statistics may be made. Model-based ‘predictability’ studies, which probe these limits and investigate the physical mechanisms involved, support the potential for the skilful prediction of annual to decadal average temperature and, to a lesser extent precipitation. Predictions for averages of temperature, over large regions of the planet and for the global mean, exhibit positive skill when verified against observations for forecast...

Global nitrous oxide budget (1980–2020)

Sat, 8 Nov 2025 00:00:00 +0000

Abstract. Nitrous oxide (N2O) is a long-lived potent greenhouse gas and stratospheric ozone-depleting substance that has been accumulating in the atmosphere since the preindustrial period. The mole fraction of atmospheric N2O has increased by nearly 25 % from 270 ppb (parts per billion) in 1750 to 336 ppb in 2022, with the fastest annual growth rate since 1980 of more than 1.3 ppb yr−1 in both 2020 and 2021. According to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR6), the relative contribution of N2O to the total enhanced effective radiative forcing of greenhouse gases was 6.4 % for 1750–2022. As a core component of our global greenhouse gas assessments coordinated by the Global Carbon Project (GCP), our global N2O budget incorporates both natural and anthropogenic sources and sinks and accounts for the interactions between nitrogen additions and the biogeochemical processes that control N2O...

A multi-model assessment of the Global Warming Potential of hydrogen

Sat, 8 Nov 2025 00:00:00 +0000

With increasing global interest in molecular hydrogen to replace fossil fuels, more attention is being paid to potential leakages of hydrogen into the atmosphere and its environmental consequences. Hydrogen is not directly a greenhouse gas, but its chemical reactions change the abundances of the greenhouse gases methane, ozone, and stratospheric water vapor, as well as aerosols. Here, we use a model ensemble of five global atmospheric chemistry models to estimate the 100-year time-horizon Global Warming Potential (GWP100) of hydrogen. We estimate a hydrogen GWP100 of 11.6 ± 2.8 (one standard deviation). The uncertainty range covers soil uptake, photochemical production of hydrogen, the lifetimes of hydrogen and methane, and the hydroxyl radical feedback on methane and hydrogen. The hydrogen-induced changes are robust across the different models. It will be important to keep hydrogen leakages at a minimum to accomplish the benefits of switching to a hydrogen economy.

Data-rate-aware FPGA-based Acceleration Framework for Streaming Applications

Sat, 8 Nov 2025 00:00:00 +0000

In heterogeneous architectures, FPGAs are not only expected to provide higher performance, but also to provide a more energy efficient solution for computationally intensive tasks. While parallelism and pipelining enhance performance on FPGA platforms, the data transfer rate from/to off-chip memory can cause performance degradation. We propose an automated high-level synthesis framework for FPGA-based acceleration of nested loops on large multidimensional input data sets. Given the high-level of parallelism in such applications, our proposed data prefetching algorithm determines the data rate for each parallel datapath. The empirical results on a case study in scientific computing show that FPGA mapping of such nested loops accelerates the application compared to traditional mapping on multicores. The FPGA-accelerated computation results in 3x speedup in runtime and 27x energy-delay-product savings compared to multicore computation.

Point of Departure

Sat, 8 Nov 2025 00:00:00 +0000

1.1. The Setting This chapter describes the information basis for the Fifth Assessment Report (AR5) of IPCC Working Group II (WGII) and the rationale for its structure. As the starting point of WGII AR5, the chapter begins with an analysis of how the literature for the assessment has developed through time and proceeds with an overview of how the framing and content of the WGII reports have changed since the first IPCC report was published in 1990. The future climate scenarios used in AR5 are a marked change from those used in the Third (TAR, 2001) and Fourth (AR4, 2007) Assessment Reports; this shift is described here, along with the new AR5 guidance for communicating scientific uncertainty. The chapter provides a summary of the most relevant key findings from the IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation (IPCC, 2011), the IPCC Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (IPCC, 2012),...

The Energy Exascale Earth System Model Version 3: 1. Overview of the Atmospheric Component

Sat, 8 Nov 2025 00:00:00 +0000

Abstract This paper describes the atmospheric component of the US Department of Energy's Energy Exascale Earth System Model (E3SM) version 3. Significant updates have been made to the atmospheric physics compared to earlier versions. Specifically, interactive gas chemistry has been implemented, along with improved representations of aerosols and dust emissions. A new stratiform cloud microphysics scheme more physically treats ice processes and aerosol‐cloud interactions. The deep convection parameterization has been largely improved with sophisticated microphysics for convective clouds, making model convection sensitive to large‐scale dynamics, and incorporating the dynamical and physical effects of organized mesoscale convection. Improvements in aerosol wet removal processes and parameter re‐tuning of key aerosol and cloud processes have improved model aerosol radiative forcing. The model's vertical resolution has increased from 72 to 80 layers with the extra eight layers added...

Uncertain climate effects of anthropogenic reactive nitrogen

Sat, 8 Nov 2025 00:00:00 +0000

Uncertain climate effects of anthropogenic reactive nitrogen

Climate change impacts the non-market value of nature: A case study of birding cultural ecosystem services in South Africa

Wed, 5 Nov 2025 00:00:00 +0000

Climate change and human activities are increasingly straining global ecosystems, threatening the essential benefits - ecosystem services - they provide to humanity. Among these, cultural ecosystem services (CES) enhance human well-being by providing non-material non-market value beyond what is accounted for within our market based economies. Measuring the impacts of global change on these benefits remains challenging and underdeveloped. In this study, we quantify the current and future non-market use value of birding CES across South Africa, a biodiversity hotspot, by integrating social sensing data, machine learning, and econometric methods. We reveal national patterns of birding CES use and non-market value, identify beneficiaries, and demonstrate that domestic and international beneficiaries are driven by distinct social-ecological dynamics, leading to differing CES vulnerabilities under future climate and biodiversity scenarios. While most protected areas are projected to...

Tipping Points of Amazonian Forests: Beyond Myths and Toward Solutions

Sat, 25 Oct 2025 00:00:00 +0000

Amazon forests are undergoing rapid transformations driven by deforestation, climate change, fire, and other anthropogenic pressures, leading to the hypothesis that they may be nearing a catastrophic tipping point—beyond which ecosystems could shift to a permanently altered state. This review revisits the concept of an Amazon tipping point and assesses the risk of forest collapse from an ecological perspective. We synthesize evidence showing that environmental stressors can drive critical ecosystem transitions, either gradually through incremental loss of resilience or abruptly via synergistic feedbacks. The interplay between climate and land-use change amplifies risks to biodiversity, ecosystem services, and livelihoods. Yet, there is limited evidence for a single, system-wide tipping point. Instead, the Amazon's resilience—although not unlimited—offers meaningful pathways for recovery. The most immediate and effective strategies to support this resilience include slowing forest...

Short‐Term Forecasting of Wind Gusts at Airports Across CONUS Using Machine Learning

Wed, 22 Oct 2025 00:00:00 +0000

Abstract Short‐term forecasting of wind gusts, particularly those of higher intensity, is of great societal importance but is challenging due to the presence of multiple gust generation mechanisms. Wind gust observations from eight high‐passenger‐volume airports across the continental United States (CONUS) are summarized and used to develop predictive models of wind gust occurrence and magnitude. These short‐term (same hour) forecast models are built using multiple logistic and linear regression, as well as artificial neural networks (ANNs) of varying complexity. A suite of 19 upper‐air predictors drawn from the ERA5 reanalysis and an autoregressive (AR) term are used. Stepwise procedures instruct predictor selection, and resampling is used to quantify model stability. All models are developed separately for the warm (April–September) and cold (October–March) seasons. Results show that ANNs of 3–5 hidden layers (HLs) generally exhibit higher hit rates than logistic regression...

Developing a Disaster-Ready Power Grid Agent Through Geophysically-Informed Fault Event Scenarios

Wed, 22 Oct 2025 00:00:00 +0000

Management of the nation’s power grid over the coming decades will need to consider multiple climate-driven threats to the power system that can be stressful or even detrimental to its operations. During disasters, grid operators suffer from cognitive overload where the electric grid is severely impacted by the weather, yet grid operators have limited awareness of these factors. Meanwhile, the electric grid is facing an explosion of data coming from a variety of sources which can enable the operator to evaluate the risks and develop mitigation strategies against hazardous events. In this work, we processed heterogeneous environmental and power grid data to learn and model grid behaviour caused by extreme weather events. In this study, we focused on two weather-driven hazards, hurricanes and wildfires, which were analysed for the electric grid of Texas. We then used this data to train a Reinforcement Learning (RL) agent by analysing and predicting future behaviour of the grid during...

Near real-time indicators of burn severity in the western U.S. from active fire tracking

Wed, 22 Oct 2025 00:00:00 +0000

BackgroundTimely information on wildfire burn severity is critical to assess and mitigate potential post-fire impacts on soils, vegetation, and hillslope stability. Tracking individual fire spread and intensity using satellite active fire data provides a pathway to near real-time (NRT) information. Here, we generated a large database (n = 2177) of wildfire events in the western United States (U.S.) between 2012 and 2021 using active fire detections from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Suomi National Polar-orbiting Partnership (SNPP) satellite and the Fire Events Data Suite (FEDS) algorithm to track large fire growth every 12 h. We integrated fire tracking data with final fire perimeters and burn severity data from the Monitoring Trends in Burn Severity (MTBS) program to evaluate the relationship between burn severity and fire behavior metrics derived from the fire tracking approach, including the rate of fire spread and average fire radiative...

Investigating the Global Biogeophysical Impact of Area and Mass Based Wood Harvest in a Vegetation Demography Model

Tue, 21 Oct 2025 00:00:00 +0000

Abstract Wood harvesting alters land surface properties and energy redistribution, but there is a lack of studies estimating these changes on a global scale. We coupled a vegetation demographic model, the Functionally Assembled Terrestrial Ecosystem Simulator, with the E3SM land model to perform offline model simulation to investigate the land biogeophysical responses, including canopy coverage, leaf area index, albedo, surface roughness length, and energy fluxes, to historical wood harvest on the global scale. In this study, we found 50% less harvested carbon (C) when choosing the area‐based harvest rate as driving data that has not been spatially harmonized, compared to reharmonized mass‐based harvesting. By considering the uncertainty from reconstruction of historical wood harvest time series and the choice of wood harvest approach in the model, continuous wood harvest (1850–2015) results in 5%–10% of canopy coverage loss, contributing 0.5%–1% increase of albedo over disturbed...

SNICAR-ADv3: a community tool for modeling spectral snow albedo

Wed, 8 Oct 2025 00:00:00 +0000

The Snow, Ice, and Aerosol Radiative (SNICAR) model has been used in various capacities over the last 15 years to model the spectral albedo of snow with light-absorbing constituents (LACs). Recent studies have extended the model to include an adding-doubling two-stream solver and representations of non-spherical ice particles; carbon dioxide snow; snow algae; and new types of mineral dust, volcanic ash, and brown carbon. New options also exist for ice refractive indices and solar-zenith-angle-dependent surface spectral irradiances used to derive broadband albedo. The model spectral range was also extended deeper into the ultraviolet for studies of extraterrestrial and high-altitude cryospheric surfaces. Until now, however, these improvements and capabilities have not been merged into a unified code base. Here, we document the formulation and evaluation of the publicly available SNICAR-ADv3 source code, web-based model, and accompanying library of constituent optical properties....

Contrasting Arctic Amplification Response in the Community Earth System Model Large Ensembles and Implications for the North Atlantic Region

Wed, 8 Oct 2025 00:00:00 +0000

The response of the polar jet to climate warming and rapid Arctic change is a leading uncertainty in climate projections and critical to the future of mid-latitude surface weather. Previous studies suggest that CMIP5-6 model projections fall into two groups of either Arctic- or tropically-driven climate change, especially in the North Atlantic. Here, we present distinct warming patterns emerging by the late 21st century between the first two generations of the Community Earth System Model Large Ensemble (CESM-LE) and use daily diagnostics to assess associated changes in mid-latitude circulation. We show that the subsequent versions of CESM represent categorically different storylines of North Atlantic climate change. The first version of CESM-LE (CESM1-LE, hereafter LENS1) exhibits severe Arctic amplification (AA) along with minor reductions in jet waviness. In contrast, CESM2-LE (hereafter LENS2) presents subdued AA, a more pronounced North Atlantic warming hole, and a late-century...

Valuing co-benefits of forest fuels treatment for reducing wildfire risk in California's Sierra Nevada

Wed, 8 Oct 2025 00:00:00 +0000

As wildfires in the western United States grow in frequency and severity, forest fuels treatment has been increasingly recognized as essential for enhancing forest resilience and mitigating wildfire risks. However, the economic valuation of the treatment's co-benefits remains underexplored, limiting integration into financial and policy decision making. Using highly forested land in California's Sierra Nevada as study areas, this study provides a methodology to quantify the economic benefits of forest fuels treatment in mitigating wildfire-induced losses across multiple ecosystem services, including carbon storage, timber provisioning, erosion regulation, and air-quality regulation. Integrating historical data on forest disturbances, ecological variables, and market-based ecosystem service valuation models, we demonstrate that treatment can substantially reduce wildfire risk and deliver measurable, significant economic benefits at a landscape level. The magnitude of these benefits...

Disentangling the chemistry and transport impacts of the quasi-biennial oscillation on stratospheric ozone