Publications by authors named "Lamarque J"

Article Synopsis
  • * This reduction is due to the movement of ozone-poor and halogen-rich air from the Arctic, which impacts ozone levels further south by decreasing the overall tropospheric ozone column by around 4%.
  • * Comparatively, the current effect of Arctic halogens on ozone reduction is less significant than it was in preindustrial times, highlighting a complex relationship between human pollution and natural halogen contributions that should be better represented in global climate models.
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Tropospheric ozone (O) is a strong greenhouse gas, particularly in the upper troposphere (UT). Limited observations point to a continuous increase in UT O in recent decades, but the attribution of UT O changes is complicated by large internal climate variability. We show that the anthropogenic signal ("fingerprint") in the patterns of UT O increases is distinguishable from the background noise of internal variability.

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Short-term exposure to ground-level ozone in cities is associated with increased mortality and is expected to worsen with climate and emission changes. However, no study has yet comprehensively assessed future ozone-related acute mortality across diverse geographic areas, various climate scenarios, and using CMIP6 multi-model ensembles, limiting our knowledge on future changes in global ozone-related acute mortality and our ability to design targeted health policies. Here, we combine CMIP6 simulations and epidemiological data from 406 cities in 20 countries or regions.

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Background: Morbidity burdens from ambient air pollution are associated with market and non-market costs and are therefore important for policymaking. The estimation of morbidity burdens is based on concentration-response functions (CRFs). Most existing CRFs for short-term exposures to PM assume a fixed risk estimate as a log-linear function over an extrapolated exposure range, based on evidence primarily from Europe and North America.

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  • Atmospheric methane is a significant greenhouse gas with both natural and human-made sources, and adding chlorine to the atmosphere has been suggested as a way to reduce methane's impact on global warming.
  • Research indicates that to effectively lower methane levels by specific targets (20%, 45%, or 70% by 2050), a substantial increase in chlorine emissions (from 630 to 1880 Tg Cl/year) is required due to the non-linear nature of atmospheric chemistry.
  • The proposed increase in chlorine emissions could lead to a decrease in surface temperature by up to 0.6 °C by 2050, but careful consideration of the environmental implications, including air quality and ocean acidity, is essential before proceeding with this approach.
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  • Ocean-emitted short-lived halogens are common in the atmosphere, and their natural emissions have increased due to human activities since pre-industrial times, along with added human-made halocarbons.
  • These halogens have a significant indirect cooling effect on Earth's radiative balance, calculated at about -0.13 watts per square meter, influenced primarily by their effects on ozone and moderated by methane and aerosols.
  • This cooling effect has risen by 61% since 1750 and is expected to change by 18-31% by 2100, highlighting the need to include short-lived halogens in climate models for better predictions of the climate system.
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Background: The need for developing new biomarkers is increasing with the emergence of many targeted therapies. Artificial Intelligence (AI) algorithms have shown great promise in the medical imaging field to build predictive models. We developed a prognostic model for solid tumour patients using AI on multimodal data.

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The mechanisms underlying decadal variability in Arctic sea ice remain actively debated. Here, we show that variability in boreal biomass burning (BB) emissions strongly influences simulated Arctic sea ice on multidecadal time scales. In particular, we find that a strong acceleration in sea ice decline in the early 21st century in the Community Earth System Model version 2 (CESM2) is related to increased variability in prescribed BB emissions in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) through summertime aerosol-cloud interactions.

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CH is the most abundant reactive greenhouse gas and a complete understanding of its atmospheric fate is needed to formulate mitigation policies. Current chemistry-climate models tend to underestimate the lifetime of CH, suggesting uncertainties in its sources and sinks. Reactive halogens substantially perturb the budget of tropospheric OH, the main CH loss.

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Article Synopsis
  • The data descriptor covers key scientific insights from General Circulation Models (GCMs) used in the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), focusing on climate responses to changes in greenhouse gases, aerosols, and solar radiation.
  • It provides global and annual mean results from a wide range of coupled atmospheric-ocean GCM simulations, emphasizing the importance of single idealized perturbations to understand climate behavior better.
  • The dataset is designed to be user-friendly, offering an accessible way to extract files, and is expected to support research on complex GCMs and Earth System Models in the Coupled Model Intercomparison Project.
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The catalytic depletion of Antarctic stratospheric ozone is linked to anthropogenic emissions of chlorine and bromine. Despite its larger ozone-depleting efficiency, the contribution of ocean-emitted iodine to ozone hole chemistry has not been evaluated, due to the negligible iodine levels previously reported to reach the stratosphere. Based on the recently observed range (0.

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The history of molecular oxygen (O) in Earth's atmosphere is still debated; however, geological evidence supports at least two major episodes where O increased by an order of magnitude or more: the Great Oxidation Event (GOE) and the Neoproterozoic Oxidation Event. O concentrations have likely fluctuated (between 10 and 1.5 times the present atmospheric level) since the GOE ∼2.

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Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. The effects of the ozone hole and the associated increase in incoming UV radiation on terrestrial and marine ecosystems are well established; however, the impact on geochemical cycles of ice photoactive elements, such as iodine, remains mostly unexplored. Here, we present the first iodine record from the inner Antarctic Plateau (Dome C) that covers approximately the last 212 years (1800-2012 CE).

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The Toba eruption ∼74,000 y ago was the largest volcanic eruption since the start of the Pleistocene and represents an important test case for understanding the effects of large explosive eruptions on climate and ecosystems. However, the magnitude and repercussions of climatic changes driven by the eruption are strongly debated. High-resolution paleoclimate and archaeological records from Africa find little evidence for the disruption of climate or human activity in the wake of the eruption in contrast with a controversial link with a bottleneck in human evolution and climate model simulations predicting strong volcanic cooling for up to a decade after a Toba-scale eruption.

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Exposure to ambient PM pollution has been linked to multiple adverse health effects. Additional effects have been identified in the literature and there is a need to understand its potential role in high prevalence diseases. In response to recent indications of PM as a risk factor for dementia, we examine the evidence by systematically reviewing the epidemiologic literature, in relation to exposure from ambient air pollution, household air pollution, secondhand smoke, and active smoking.

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Many Chemistry-Climate Models (CCMs) include a simplified treatment of brominated very short-lived (VSL) species by assuming CHBr as a surrogate for VSL. However, neglecting a comprehensive treatment of VSL in CCMs may yield an unrealistic representation of the associated impacts. Here, we use the Community Atmospheric Model with Chemistry (CAM-Chem) CCM to quantify the tropospheric and stratospheric changes between various VSL chemical approaches with increasing degrees of complexity (i.

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Estimates of ground-level ozone concentrations are necessary to determine the human health burden of ozone. To support the Global Burden of Disease Study, we produce yearly fine resolution global surface ozone estimates from 1990 to 2017 through a data fusion of observations and models. As ozone observations are sparse in many populated regions, we use a novel combination of the MFusion and Bayesian Maximum Entropy (BME) methods.

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The SARS-COV-2 pandemic has put pressure on intensive care units, so that identifying predictors of disease severity is a priority. We collect 58 clinical and biological variables, and chest CT scan data, from 1003 coronavirus-infected patients from two French hospitals. We train a deep learning model based on CT scans to predict severity.

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On present-day Earth, dust emissions are restricted only to a few desert regions mainly due to the distribution of land vegetation. The atmospheric dust loading is thus relatively small and has a slight cooling effect on the surface climate. For the Precambrian (before ~540 Ma), however, dust emission might be much more widespread since land vegetation was absent.

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For the current generation of earth system models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), the range of equilibrium climate sensitivity (ECS, a hypothetical value of global warming at equilibrium for a doubling of CO) is 1.8°C to 5.6°C, the largest of any generation of models dating to the 1990s.

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Importance: Hyperprogressive disease (HPD) is an aggressive pattern of progression reported for patients treated with programmed cell death 1 (PD-1)/programmed cell death 1 ligand (PD-L1) inhibitors as a single agent in several studies. However, the use of different definitions of HPD introduces the risk of describing different tumoral behaviors.

Objective: To assess the accuracy of each HPD definition to identify the frequency of HPD and the association with poorer outcomes of immune-checkpoint inhibitor (ICI) treatment in patients with advanced non-small cell lung cancer (NSCLC) and to provide an optimized and homogenized definition based on all previous criteria for identifying HPD.

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Purpose: The second edition of the artificial intelligence (AI) data challenge was organized by the French Society of Radiology with the aim to: (i), work on relevant public health issues; (ii), build large, multicentre, high quality databases; and (iii), include three-dimensional (3D) information and prognostic questions.

Materials And Methods: Relevant clinical questions were proposed by French subspecialty colleges of radiology. Their feasibility was assessed by experts in the field of AI.

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Dimethyl sulfide (DMS), emitted from the oceans, is the most abundant biological source of sulfur to the marine atmosphere. Atmospheric DMS is oxidized to condensable products that form secondary aerosols that affect Earth's radiative balance by scattering solar radiation and serving as cloud condensation nuclei. We report the atmospheric discovery of a previously unquantified DMS oxidation product, hydroperoxymethyl thioformate (HPMTF, HOOCHSCHO), identified through global-scale airborne observations that demonstrate it to be a major reservoir of marine sulfur.

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Quantifying the efficacy of different climate forcings is important for understanding the real-world climate sensitivity. This study presents a systematic multimodel analysis of different climate driver efficacies using simulations from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP). Efficacies calculated from instantaneous radiative forcing deviate considerably from unity across forcing agents and models.

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