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The Amazon rainforest is the largest source of biogenic volatile organic compounds (BVOCs) to the atmosphere. To understand the distribution and chemistry of BVOCs, airborne and ground-based measurements of BVOCs are conducted over the Amazon rainforest in the CAFE-Brazil campaign (December 2022–January 2023), including diel (24-hour) profiles between 0.3-14 km for isoprene, its oxidation products, and total monoterpenes. Although daytime deep convective transport of BVOCs is rendered ineffective by photochemical loss, nocturnal deep-convection exports considerable BVOC quantities to high altitudes, extending the chemical influence of the rainforest to the upper troposphere, and priming it for rapid organic photochemistry and particle formation at dawn. After contrasting pristine and deforested areas, a BVOC sensitivity analysis is performed using a chemistry-climate model. Here we show that reducing BVOC emissions, decreased upper tropospheric ozone, increased lower tropospheric hydroxyl radicals, shortened the methane lifetime, with the net effect of enhancing climate warming through ozone and aerosols. Convection shapes BVOC dynamics over the Amazon rainforest, driving dawn photochemistry in the upper troposphere. Changes in BVOC emissions can strongly impact regional and global atmospheric chemistry.

Biogenic volatile organic compounds (BVOCs) are emitted in large quantities from the terrestrial biosphere and play a significant role in atmospheric gaseous and aerosol compositions. Secondary organic aerosols (SOAs) resulting from BVOC oxidation affect the radiation budget both directly, through the scattering and absorption of sunlight, and indirectly, by modifying cloud properties. Human activities have extensively altered natural vegetation cover, primarily by converting forests into agricultural land. In this work, a global atmospheric chemistry–climate model, coupled with a dynamic global vegetation model, was employed to study the impacts of perturbing the biosphere through human-induced land use change, thereby exploring changes in BVOC emissions and the atmospheric aerosol burden. A land use scheme was implemented to constrain tree plant functional type (PFT) cover based on land transformation fraction maps from the year 2015. Two scenarios were evaluated: (1) one comparing present-day land cover, which includes areas deforested for crops and grazing land, with potential natural vegetation (PNV) cover simulated by the model, and (2) an extreme reforestation scenario in which present-day grazing land is restored to natural vegetation levels. We find that, compared to the PNV scenario, present-day deforestation results in a 26 % reduction in BVOC emissions, which decreases the global biogenic SOA (bSOA) burden by 0.16 Tg (a decrease of 29 %), while the total organic aerosol (OA) burden decreases by 0.17 Tg (a reduction of 9 %). On the other hand, the extreme reforestation scenario, compared to present-day land cover, suggests an increase in BVOC emissions of 22 %, which increases the bSOA burden by 0.11 Tg and the total OA burden by 0.12 Tg – increases of 26 % and 6 %, respectively. For the present-day deforestation scenario, we estimate a positive total radiative effect (aerosol + cloud) of 60.4 mW m−2 (warming) relative to the natural vegetation scenario, while for the extreme reforestation scenario, we report a negative (cooling) effect of 38.2 mW m−2 relative to current vegetation cover.

Human activities have profoundly altered natural vegetation, primarily by converting pristine natural land to agriculture and grazing. Land cover change (LCC) influences the Earth system through modifications of surface albedo, roughness length, evapotranspiration, and atmospheric composition. This work investigates how LCC-driven changes in biogenic volatile organic compound (BVOC) fluxes, anthropogenic surface emissions, natural soil NO emissions, and O3 deposition fluxes affect atmospheric chemistry. The chemistry–climate model EMAC was used to compare: (1) present-day land cover, which includes areas deforested for crops and grazing, with the potential natural vegetation (PNV) cover simulated by the model, and (2) an extreme reforestation scenario where grazing land is restored to natural vegetation. Our results show that the expansion of agricultural land reduces global BVOC emissions, leading to larger annual average surface OH concentrations (+5.7 %) and lower CO mixing ratios (−6.2 %), despite increased CO from agricultural burning. Meanwhile, NOx mixing ratios increase (+7.8 %) due to enhanced anthropogenic and natural soil sources. While regional ozone responses vary, global ozone production sensitivity shifts from a NOx- to a VOC-sensitive regime. These changes influence radiative forcing with reductions in tropospheric O3 and CH4 lifetimes exerting a combined radiative effect of −60 mW m−2 (cooling), partially offsetting the warming from reduced BVOC-driven aerosol formation. Reforestation of grazing areas reverses these trends to some extent, though with a weaker response.

Emissions of biogenic volatile organic compounds (BVOCs) from the terrestrial biosphere play a significant role in major atmospheric processes. BVOCs are highly reactive compounds that influence the atmosphere's oxidation capacity and also serve as precursors for the formation of aerosols that influence global radiation budgets. Emissions depend on the response of vegetation to atmospheric conditions (primarily temperature and light), as well as other stresses, e.g. from droughts and herbivory. The El Niño–Southern Oscillation (ENSO) is a naturally occurring cycle arising from anomalies in the sea surface temperature (SST) in the tropical Pacific. ENSO perturbs the natural seasonality of weather systems on both global and regional scales and is considered the most significant driver of climate variability. Several studies have evaluated the sensitivity of BVOC fluxes during ENSO events using historical transient simulations. While this approach employs realistic scenarios, it is difficult to assess the impact of ENSO alone given the multiple types of climate forcing, e.g. from anthropogenic emissions of CO2 and aerosol. In this study, a global atmospheric chemistry–climate model with enabled interactive vegetation was used to conduct two sets of simulations: (1) isolated ENSO event simulations, in which a single ENSO event is used to perturb otherwise baseline conditions, and (2) sustained ENSO simulations, in which the same ENSO conditions are reproduced for an extended period of time. From the isolated ENSO events, we present global and regional BVOC emission changes resulting from the immediate response of vegetation to atmospheric states. More focus is given to the sustained ENSO simulations, which have the benefit of reducing the internal variability for more robust statistics when linking atmospheric and vegetation variables with BVOC flux anomalies. Additionally, these simulations explore long-term changes in the biosphere with potential shifts in vegetation in this possible climate mode, accounting for the prospect of increased intensity and frequency of ENSO with climate change. Our results show that strong El Niño events increase global isoprene emission fluxes by 2.9 % and that one single ENSO event perturbs the Earth system so markedly that BVOC emission fluxes do not return to baseline emissions within several years after the event. We show that persistent ENSO conditions shift the vegetation to a new quasi-equilibrium state, leading to an amplification of BVOC emission changes with up to a 19 % increase in isoprene fluxes over the Amazon. We provide evidence that BVOC-induced changes in plant phenology, such as the leaf area index (LAI), have a significant influence on BVOC emissions in the sustained ENSO climate mode.

Earth system models (ESMs) integrate previously separate models of the ocean, atmosphere and vegetation into one comprehensive modelling system enabling the investigation of interactions between different components of the Earth system. Global isoprene and monoterpene emissions from terrestrial vegetation, which represent the most important source of volatile organic compounds (VOCs) in the Earth system, need to be included in global and regional chemical transport models given their major chemical impacts on the atmosphere. Due to the feedback of vegetation activity involving interactions with weather and climate, a coupled modelling system between vegetation and atmospheric chemistry is recommended to address the fate of biogenic volatile organic compounds (BVOCs). In this work, further development in linking LPJ-GUESS, a global dynamic vegetation model, to the atmospheric-chemistry-enabled atmosphere–ocean general circulation model EMAC is presented. New parameterisations are included to calculate the foliar density and leaf area density (LAD) distribution from LPJ-GUESS information. The new vegetation parameters are combined with existing LPJ-GUESS output (i.e. leaf area index and cover fractions) and used in empirically based BVOC modules in EMAC. Estimates of terrestrial BVOC emissions from EMAC's submodels ONEMIS and MEGAN are evaluated using (1) prescribed climatological vegetation boundary conditions at the land–atmosphere interface and (2) dynamic vegetation states calculated in LPJ-GUESS (replacing the “offline” vegetation inputs). LPJ-GUESS-driven global emission estimates for isoprene and monoterpenes from the submodel ONEMIS were 546 and 102 Tg yr-1, respectively. MEGAN determines 657 and 55 Tg of isoprene and monoterpene emissions annually. The new vegetation-sensitive BVOC fluxes in EMAC are in good agreement with emissions from the semi-process-based module in LPJ-GUESS. The new coupled system is used to evaluate the temperature and vegetation sensitivity of BVOC fluxes in doubling CO2 scenarios. This work provides evidence that the new coupled model yields suitable estimates for global BVOC emissions that are responsive to vegetation dynamics. It is concluded that the proposed model set-up is useful for studying land–biosphere–atmosphere interactions in the Earth system.

Over the years, the Maltese Islands have seen a marked rise in the prevalence of artificial lighting at night. The most evident type of light pollution arising from this evolution in anthropogenic night-time lighting is artificial skyglow via partial back-scattering in the atmosphere, leading to an increase in the Night Sky Brightness (NSB). The importance of understanding and quantifying the geographical distribution of the NSB is underscored by the adverse impact of light pollution on various spheres, from astronomical observation to ecology and human health. For the first time, we present a detailed map of the NSB over the Maltese archipelago carried out with Unihedron Sky Quality Meters. We show that the vast majority of the area of the Maltese Islands is heavily light polluted, with 87% of the area registering a NSB \\(<\\) 20.39~mag\\(_{\\rm SQM}\\)/arcsec\\(^2\\) (Bortle Class 5 or higher) and 37.3% \\(<\\) 19.09~mag\\(_{\\rm SQM}\\)/arcsec\\(^2\\) (Bortle Class 6 or higher), with the Milky Way being visible for only 12.8% of the area (adopting a visibility threshold \\(>\\) 20.4 - 21.29~mag\\(_{\\rm SQM}\\)/arcsec\\(^2\\); Bortle Class 4). Coastal Dark Sky Heritage Areas on the island of Gozo retain generally darker skies than the rest of the islands, but light pollution originating further inland is encroaching upon and adversely affecting these sites. The methodology presented in this study can be adopted for continued future studies in Malta as well as for other regions.

Anti-programmed death-1 (anti-PD-1) immunotherapy reinvigorates CD8 T cell responses in patients with cancer but PD-1 is also expressed by other immune cells, including follicular helper CD4 T cells (Tfh) which are involved in germinal centre responses. Little is known, however, about the effects of anti-PD-1 immunotherapy on noncancer immune responses in humans. To investigate this question, we examined the impact of anti-PD-1 immunotherapy on the Tfh–B cell axis responding to unrelated viral antigens. Following influenza vaccination, a subset of adults receiving anti-PD-1 had more robust circulating Tfh responses than adults not receiving immunotherapy. PD-1 pathway blockade resulted in transcriptional signatures of increased cellular proliferation in circulating Tfh and responding B cells compared with controls. These latter observations suggest an underlying change in the Tfh–B cell and germinal centre axis in a subset of immunotherapy patients. Together, these results demonstrate dynamic effects of anti-PD-1 therapy on influenza vaccine responses and highlight analytical vaccination as an approach that may reveal underlying immune predisposition to adverse events.Patients with cancer undergoing anti-PD-1 immune checkpoint blockade can experience immune-related adverse effects. Wherry and colleagues examined the immunity elicited upon immunization of patients with cancer and report that anti-PD-1 immunotherapy dynamically affects influenza vaccine-induced immune responses.

Apoptotic cells communicate to phagocytic cells through releasing soluble factors and apoptotic cell-derived extracellular vesicles. However, whether there are additional factors that remain attached at the site of cell death to signal to phagocytic cells is currently unknown. Here we show that apoptotic cell retraction generates a membrane-encased, F-actin-rich ‘footprint’ tightly anchored to the substrate that marks the site of cell death, coined ‘the FOotprint Of Death’ or FOOD. Formation of FOOD is observed frequently across many different cell types, apoptotic stimuli and surface composition. Mechanistically, FOOD formation is regulated by the protein kinase ROCK1. 3D time-lapse microscopy studies revealed that FOOD vesicularises into distinct large extracellular vesicles. These extracellular vesicles expose the ‘eat-me’ signal phosphatidylserine and can function to ‘flag’ the site of cell death to neighbouring phagocytes for efferocytosis. Under a viral infection setting, FOOD can harbour viral proteins and virions, and propagate infection to healthy cells. Together, this study has revealed another route of apoptotic cell-phagocyte communication. Apoptotic cells often release extracellular vesicles that aid in their clearance and provide molecular information to cellular neighbours. Here, the authors show that some adherent apoptotic cells also create vesicles that remain attached at the site of death.

BackgroundTrauma video review (TVR) is an evolving technology that can be used to measure technical and non-technical aspects of trauma care leading to meaningful improvements. Only 30% of centers currently use TVR, with non-users citing medicolegal concerns, staff discomfort with recording, and resource constraints as barriers to implementation. Multiple studies have shown established TVR programs are well-perceived by staff. Little is known about perceptions prior to, and after implementation of a new program.ObjectiveThis study evaluated changes in TVR perceptions following implementation of a new program.MethodsA 15-question survey was distributed to emergency department and trauma surgery providers at a level I trauma center prior to, and 1 year after, implementation of TVR. A 5-point Likert scale was used to evaluate perceptions of the value of TVR, measures of team dynamics, and staff discomfort with recording.ResultsA total of 106 pre-implementation and 82 post-implementation responses were recorded. Perceptions in several domains improved post-implementation including team leader effectiveness (3 (3–4) to 4 (3–4); p=0.002), communication (3 (3–4) to 4 (3–4); p<0.001), and self confidence in role (4 (3–4) to 4 (4–5); p=0.001). Staff discomfort with recording decreased post-implementation (3 (2–4) to 2 (2–3); p=0.002).ConclusionOur study shows that perceptions of TVR changed favorably after implementation, particularly perceptions of team dynamics and provider discomfort with recording. These results can be used to mitigate staff concerns about TVR and encourage the development of new programs.Level of evidenceIV.