Declining precipitation frequency may drive earlier leaf senescence by intensifying drought stress and enhancing drought acclimation.

Precipitation is an important factor influencing the date of foliar senescence, which in turn affects carbon uptake of terrestrial ecosystems. However, the temporal patterns of precipitation frequency and its impact on foliar senescence date remain largely unknown. Using both long-term carbon flux data and satellite observations across the Northern Hemisphere, we show that, after excluding impacts from of temperature, radiation and total precipitation by partial correlation analysis, declining precipitation frequency may drive earlier foliar senescence date from 1982 to 2022.

Understanding the spread of agriculture in the Western Mediterranean (6th-3rd millennia BC) with Machine Learning tools.

The first Neolithic farmers arrived in the Western Mediterranean area from the East. They established settlements in coastal areas and over time migrated to new environments, adapting to changing ecological and climatic conditions. While farming practices and settlements in the Western Mediterranean differ greatly from those known in the Eastern Mediterranean and central Europe, the extent to which these differences are connected to the local environment and climate is unclear.

Disruption of seasonal influenza circulation and evolution during the 2009 H1N1 and COVID-19 pandemics in Southeastern Asia.

East, South, and Southeast Asia (together referred to as Southeastern Asia hereafter) have been recognized as critical areas fuelling the global circulation of seasonal influenza. However, the seasonal influenza migration network within Southeastern Asia remains unclear, including how pandemic-related disruptions altered this network. We leveraged genetic, epidemiological, and airline travel data between 2007-2023 to characterise the dispersal patterns of influenza A/H3N2 and B/Victoria viruses both out of and within Southeastern Asia, including during perturbations by the 2009 A/H1N1 and COVID-19 pandemics.

Rapid climate action is needed: comparing heat vs. COVID-19-related mortality.

The impacts of climate change on human health are often underestimated or perceived to be in a distant future. Here, we present the projected impacts of climate change in the context of COVID-19, a recent human health catastrophe. We compared projected heat mortality with COVID-19 deaths in 38 cities worldwide and found that in half of these cities, heat-related deaths could exceed annual COVID-19 deaths in less than ten years (at + 3.

Subseasonal Prediction of Heat-Related Mortality in Switzerland.

Heatwaves pose a range of severe impacts on human health, including an increase in premature mortality. The summers of 2018 and 2022 are two examples with record-breaking temperatures leading to thousands of heat-related excess deaths in Europe. Some of the extreme temperatures experienced during these summers were predictable several weeks in advance by subseasonal forecasts.

Assessment of Atmospheric and Surface Energy Budgets Using Observation-Based Data Products.

Accurate diagnosis of regional atmospheric and surface energy budgets is critical for understanding the spatial distribution of heat uptake associated with the Earth's energy imbalance (EEI). This contribution discusses frameworks and methods for consistent evaluation of key quantities of those budgets using observationally constrained data sets. It thereby touches upon assumptions made in data products which have implications for these evaluations.

Effects of macro vs. micro initialization and ocean initial-condition memory on the evolution of ensemble spread in the CESM2 large ensemble.

Unlabelled: "Single Model initial-condition Large Ensembles" (SMILEs) conducted with Earth system models have transformed our ability to quantify internal climate variability and forced climate change at local and regional scales. An important consideration in their experimental design is the choice of initialization procedure as this influences the duration of initial-condition memory, with implications for interpreting the temporal evolution of both the ensemble-mean and ensemble-spread. Here we leverage the strategic design of the 100-member Community Earth System Model version 2 (CESM2) SMILE to investigate the dependence of ensemble spread on the method of initialization (micro- vs.

Multiphase Chemistry in the Atmosphere.

Earth's atmosphere comprises a complex mix of gas and condensed phases, where condensed phases facilitate multiphase chemical reactions that would not occur in the gas phase alone. These reactions drive dynamic physical and chemical processes across various spatial and temporal scales, playing a crucial role in the cycling of atmospheric trace constituents. Multiphase chemistry significantly influences geochemical cycles, human health, and climate.

Spatially resolved emulated annual temperature projections for overshoot pathways.

Due to insufficient climate action over the past decade, it is increasingly likely that 1.5 °C of global warming will be exceeded - at least temporarily - in the 21 century. Such a temporary temperature overshoot carries additional climate risks which are poorly understood.

Early-twentieth-century cold bias in ocean surface temperature observations.

The observed temperature record, which combines sea surface temperatures with near-surface air temperatures over land, is crucial for understanding climate variability and change. However, early records of global mean surface temperature are uncertain owing to changes in measurement technology and practice, partial documentation, and incomplete spatial coverage. Here we show that existing estimates of ocean temperatures in the early twentieth century (1900-1930) are too cold, based on independent statistical reconstructions of the global mean surface temperature from either ocean or land data.

Geological Net Zero and the need for disaggregated accounting for carbon sinks.

Achieving net zero global emissions of carbon dioxide (CO), with declining emissions of other greenhouse gases, is widely expected to halt global warming. CO emissions will continue to drive warming until fully balanced by active anthropogenic CO removals. For practical reasons, however, many greenhouse gas accounting systems allow some "passive" CO uptake, such as enhanced vegetation growth due to CO fertilisation, to be included as removals in the definition of net anthropogenic emissions.

The added value of using convective-permitting regional climate model simulations to represent cloud band events over South America.

Climate science has long explored whether higher resolution regional climate models (RCMs) provide improved simulation of regional climates over global climate models (GCMs). The advent of convective-permitting RCMs (CPRCMs), where sufficiently fine-scale grids allow explicitly resolving rather than parametrising convection, has created a clear distinction between RCM and GCM formulations. This study investigates the simulation of tropical-extratropical (TE) cloud bands in a suite of pan-South America convective-permitting Met Office Unified Model (UM) and Weather Research and Forecasting (WRF) climate simulations.

Glaciation of liquid clouds, snowfall, and reduced cloud cover at industrial aerosol hot spots.

The ability of anthropogenic aerosols to freeze supercooled cloud droplets remains debated. In this work, we present observational evidence for the glaciation of supercooled liquid-water clouds at industrial aerosol hot spots at temperatures between -10° and -24°C. Compared with the nearby liquid-water clouds, shortwave reflectance was reduced by 14% and longwave radiance was increased by 4% in the glaciation-affected regions.

Formation of Sodium Chloride on the Surface of Sulfate-Rich Gobi Desert Salt in Response to Water Adsorption.

Dust storms in arid regions transport desert salts and dust, affecting geochemical processes, atmospheric chemistry, climate, and human health. This study examines how the gas-salt interface composition of desert salt changes with varying relative humidity (RH), using ambient pressure X-ray photoelectron spectroscopy (APXPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and molecular dynamics (MD) simulations. Ion chromatography analysis of desert salt indicates it is predominantly composed of sulfate, sodium, and magnesium ions, with traces of calcium, chloride, nitrate, and potassium ions.

Lignin-based porous carbon adsorbents for CO capture.

A major driver of global climate change is the rising concentration of atmospheric CO, the mitigation of which requires the development of efficient and sustainable carbon capture technologies. Solid porous adsorbents have emerged as promising alternatives to liquid amine counterparts due to their potential to reduce regeneration costs. Among them, porous carbons stand out for their high surface area, tailorable pore structure, and exceptional thermal and mechanical properties, making them highly robust and efficient in cycling operations.

Marine and terrestrial contributions to atmospheric deposition fluxes of methylated arsenic species.

Arsenic, a toxic element from both anthropogenic and natural sources, reaches surface environments through atmospheric cycling and dry and wet deposition. Biomethylation volatilizes arsenic into the atmosphere and deposition cycles it back to the surface, affecting soil-plant systems. Chemical speciation of deposited arsenic is important for understanding further processing in soils and bioavailability.

COVID-19 pandemic interventions reshaped the global dispersal of seasonal influenza viruses.

The global dynamics of seasonal influenza viruses inform the design of surveillance, intervention, and vaccination strategies. The COVID-19 pandemic provided a singular opportunity to evaluate how influenza circulation worldwide was perturbed by human behavioral changes. We combine molecular, epidemiological, and international travel data and find that the pandemic's onset led to a shift in the intensity and structure of international influenza lineage movement.

Dependence of aerosol-borne influenza A virus infectivity on relative humidity and aerosol composition.

We describe a novel biosafety aerosol chamber equipped with state-of-the-art instrumentation for bubble-bursting aerosol generation, size distribution measurement, and condensation-growth collection to minimize sampling artifacts when measuring virus infectivity in aerosol particles. Using this facility, we investigated the effect of relative humidity (RH) in very clean air without trace gases (except ∼400 ppm CO) on the preservation of influenza A virus (IAV) infectivity in saline aerosol particles. We characterized infectivity in terms of 99%-inactivation time, , a metric we consider most relevant to airborne virus transmission.

Resolving the Intricate Effects of Multiple Global Change Drivers on Root Litter Decomposition.

Plant roots represent about a quarter of global plant biomass and constitute a primary source of soil organic carbon (C). Yet, considerable uncertainty persists regarding root litter decomposition and their responses to global change factors (GCFs). Much of this uncertainty stems from a limited understanding of the multifactorial effects of GCFs and it remains unclear how these effects are mediated by litter quality, soil conditions and microbial functionality.

No Future Growth Enhancement Expected at the Northern Edge for European Beech due to Continued Water Limitation.

With ongoing global warming, increasing water deficits promote physiological stress on forest ecosystems with negative impacts on tree growth, vitality, and survival. How individual tree species will react to increased drought stress is therefore a key research question to address for carbon accounting and the development of climate change mitigation strategies. Recent tree-ring studies have shown that trees at higher latitudes will benefit from warmer temperatures, yet this is likely highly species-dependent and less well-known for more temperate tree species.

Global influence of soil texture on ecosystem water limitation.

Low soil moisture and high vapour pressure deficit (VPD) cause plant water stress and lead to a variety of drought responses, including a reduction in transpiration and photosynthesis. When soils dry below critical soil moisture thresholds, ecosystems transition from energy to water limitation as stomata close to alleviate water stress. However, the mechanisms behind these thresholds remain poorly defined at the ecosystem scale.

Global decline in microbial-derived carbon stocks with climate warming and its future projections.

Soil organic carbon (SOC) represents the largest terrestrial pool of organic carbon and is indispensable for mitigating climate change and sustaining soil fertility. As a major component of stable SOC, microbial-derived carbon (MDC) accounts for approximately half of the total SOC and has repercussions on climate feedback. However, our understanding of the spatial and temporal dynamics of MDC stocks is limited, hindering assessments of the long-term impacts of global warming on persistent SOC sequestration in the soil‒atmosphere carbon cycle.

Major distribution shifts are projected for key rangeland grasses under a high-emission scenario in East Africa at the end of the 21 century.

Grassland landscapes are important ecosystems in East Africa, providing habitat and grazing grounds for wildlife and livestock and supporting pastoralism, an essential part of the agricultural sector. Since future grassland availability directly affects the future mobility needs of pastoralists and wildlife, we aim to model changes in the distribution of key grassland species under climate change. Here we combine a global and regional climate model with a machine learning-based species distribution model to understand the impact of regional climate change on different key grass species.