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This study introduces CNRM‐ESM2‐1, the Earth system (ES) model of second generation developed by CNRM‐CERFACS for the sixth phase of the Coupled Model Intercomparison Project (CMIP6). CNRM‐ESM2‐1 offers a higher model complexity than the Atmosphere‐Ocean General Circulation Model CNRM‐CM6‐1 by adding interactive ES components such as carbon cycle, aerosols, and atmospheric chemistry. As both models share the same code, physical parameterizations, and grid resolution, they offer a fully traceable framework to investigate how far the represented ES processes impact the model performance over present‐day, response to external forcing and future climate projections. Using a large variety of CMIP6 experiments, we show that represented ES processes impact more prominently the model response to external forcing than the model performance over present‐day. Both models display comparable performance at replicating modern observations although the mean climate of CNRM‐ESM2‐1 is slightly warmer than that of CNRM‐CM6‐1. This difference arises from land cover‐aerosol interactions where the use of different soil vegetation distributions between both models impacts the rate of dust emissions. This interaction results in a smaller aerosol burden in CNRM‐ESM2‐1 than in CNRM‐CM6‐1, leading to a different surface radiative budget and climate. Greater differences are found when comparing the model response to external forcing and future climate projections. Represented ES processes damp future warming by up to 10% in CNRM‐ESM2‐1 with respect to CNRM‐CM6‐1. The representation of land vegetation and the CO2‐water‐stomatal feedback between both models explain about 60% of this difference. The remainder is driven by other ES feedbacks such as the natural aerosol feedback. Key Points This study introduces CNRM‐ESM2‐1 and describes its set‐up for CMIP6 Represented Earth system processes further impact the model response to external forcing than the model performance over present‐day Represented Earth system processes damp future warming by up to 10%

Convection is often assumed to be controlled by the simultaneous environmental fields. But to what extent does it also remember its past behavior? This study proposes a new framework in which the memory of previous convective-scale behavior, “microstate memory,” is distinguished from macrostate memory, and conducts numerical experiments to reveal these memory types. A suite of idealized, cloud-resolving radiative–convective equilibrium simulations in a 200-km square domain is performed with the Weather Research and Forecasting (WRF) Model. Three deep convective cases are analyzed: unorganized, organized by low-level wind shear, and self-aggregated. The systematic responses to sudden horizontal homogenization of various fields, in various atmospheric layers, designed to eliminate their specific microstructure, are compared in terms of precipitation change and time of recovery to equilibrium. Results imply a substantial role for microstate memory. Across organization types, microstructure in water vapor and temperature has a larger and longer-lasting effect on convection than in winds or hydrometeors. Microstructure in the subcloud layer or the shallow cloud layer has more impact than in the free troposphere. The recovery time scale dramatically increases from unorganized (2–3 h) to organized cases (24 h or more). Longer-time-scale adjustments also occur and appear to involve both small-scale structures and domain-mean fields. These results indicate that most convective microstate memory is stored in low-level thermodynamic structures, potentially involving cold pools and hot thermals. This memory appears strongly enhanced by convective organization. Implications of these results for parameterizing convection are discussed.

Understanding the mid-latitude atmospheric circulation response to CO 2 forcing is challenging and complex due to the strong internal variability and the multiple potential CO 2 -induced effects. While a significant poleward shift of the jet is projected in summer, changes remain uncertain in winter. In this study, we investigate the boreal winter extratropical jet response to an abrupt quadrupling of atmospheric CO 2 in the CMIP6-generation global climate model CNRM-CM6-1. First, we show that the model performs better than the former generation CNRM-CM5 model in representing the atmospheric dynamics in the northern extratropics. Then, when atmospheric CO 2 is quadrupled, CNRM-CM6-1 exhibits a strengthening and upward shift of the jet. A poleward shift is identified and robust in the Pacific in boreal winter. In the Atlantic, the jet response rather exhibits a squeezing, especially at the eastern part of the basin. It is found that changes are more robust across the Northern Hemisphere in early-winter than in late-winter season. Finally, the circulation response is broken down into individual contributions of various drivers. The uniform global mean component of the SST warming is found to explain most of the total atmospheric response to a quadrupling of CO 2 , with relatively smaller contributions from faster CO 2 effects, the SST pattern change and the Arctic sea ice decline. The cloud radiative effect contribution is also assessed and found to be rather weak in the CNRM-CM6-1 model. This study highlights that long experiments are required to isolate the wintertime circulation response from the internal variability, and that idealized experimental setups are helpful to disentangle the physical drivers.

Introduction HIV epidemics in Western and Central Africa (WCA) remain concentrated among key populations, who are often unaware of their status. HIV self-testing (HIVST) and its secondary distribution among key populations, and their partners and relatives, could reduce gaps in diagnosis coverage. We aimed to document and understand secondary HIVST distribution practices by men who have sex with men (MSM), female sex workers (FSW), people who use drugs (PWUD); and the use of HIVST by their networks in Côte d’Ivoire, Mali, and Senegal. Methods A qualitative study was conducted in 2021 involving (a) face-to-face interviews with MSM, FSW, and PWUD who received HIVST kits from peer educators (primary users) and (b) telephone interviews with people who received kits from primary contacts (secondary users). These individual interviews were audio-recorded, transcribed, and coded using Dedoose software. Thematic analysis was performed. Results A total of 89 participants, including 65 primary users and 24 secondary users were interviewed. Results showed that HIVST were effectively redistributed through peers and key populations networks. The main reported motivations for HIVST distribution included allowing others to access testing and protecting oneself by verifying the status of partners/clients. The main barrier to distribution was the fear of sexual partners’ reactions. Findings suggest that members of key populations raised awareness of HIVST and referred those in need of HIVST to peer educators. One FSW reported physical abuse. Secondary users generally completed HIVST within two days of receiving the kit. The test was used half the times in the physical presence of another person, partly for psychological support need. Users who reported a reactive test sought confirmatory testing and were linked to care. Some participants mentioned difficulties in collecting the biological sample (2 participants) and interpreting the result (4 participants). Conclusion The redistribution of HIVST was common among key populations, with minor negative attitudes. Users encountered few difficulties using the kits. Reactive test cases were generally confirmed. These secondary distribution practices support the deployment of HIVST to key populations, their partners, and other relatives. In similar WCA countries, members of key populations can assist in the distribution of HIVST, contributing to closing HIV diagnosis gaps.

Background Coverage of HIV testing remains sub-optimal in West Africa. Between 2019 and 2022, the ATLAS program distributed ~400 000 oral HIV self-tests (HIVST) in Côte d’Ivoire, Mali, and Senegal, prioritising female sex workers (FSW) and men having sex with men (MSM), and relying on secondary redistribution of HIVST to partners, peers and clients to reach individuals not tested through conventional testing. This study assesses the proportion of first-time testers among HIVST users and the associated factors. Methods A phone-based survey was implemented among HIVST users recruited using dedicated leaflets inviting them to anonymously call a free phone number. We collected socio-demographics, sexual behaviours, HIV testing history, HIVST use, and satisfaction with HIVST. We reported the proportion of first-time testers and computed associated factors using logistic regression. Results Between March and June 2021, 2 615 participants were recruited for 50 940 distributed HIVST (participation rate: 5.1%). Among participants, 30% received their HIVST kit through secondary distribution (from a friend, sexual partner, family member, or colleague). The proportion who had never tested for HIV before HIVST (first-time testers) was 41%. The main factors associated with being a first-time tester were sex, age group, education level, condom use, and secondary distribution. A higher proportion was observed among those aged 24 years or less (55% vs 32% for 25–34, aOR: 0.37 [95%CI: 0.30–0.44], and 26% for 35 years or more, aOR: 0.28 [0.21–0.37]); those less educated (48% for none/primary education vs 45% for secondary education, aOR: 0.60 [0.47–0.77], and 29% for higher education, aOR: 0.33 [0.25–0.44]). A lower proportion was observed among women (37% vs 43%, aOR: 0.49 [0.40–0.60]); those reporting always using a condom over the last year (36% vs 51% for those reporting never using them, aOR: 2.02 [1.59–2.56]); and those who received their HISVST kit through primary distribution (39% vs 46% for secondary distribution, aOR: 1.32 [1.08–1.60]). Conclusion ATLAS HIVST strategy, including secondary distribution, successfully reached a significant proportion of first-time testers. HIVST has the potential to reach underserved populations and contribute to the expansion of HIV testing services in West Africa.

Aerosol effects on cloud cover and precipitation could affect the global climate but have proven difficult to verify, because cloud and rain amounts are so strongly influenced by local meteorological conditions. Here model and observational evidence is presented that an increase in CCN concentration slightly invigorates mixed-phase convective clouds and narrows tropical convergence and rain bands, while expanding associated cloud cover particularly at mid-levels. A suite of model simulations with various approaches indicates a 4 ± 3.8% decrease in the rain-to-cloud area ratio per doubling of the CCN concentration, an effect also detected in satellite observations. Idealised numerical experiments suggest the area ratio change is due to the invigoration-induced static stability increase. Although the invigoration and cloud amount changes are much smaller than suggested in some studies, in simulations the latter cool the planet by 0.71 ± 0.25 W/m 2 in deep convective regions, suggesting a global effect of order 0.2–0.5 W/m 2 , per aerosol doubling. The contribution to present-day anthropogenic forcing is even harder to quantify but could compare to that of the direct aerosol radiative forcing. These results indicate a previously unrecognised pathway for aerosols to indirectly cool the climate by altering convective clouds dynamically.

A two-pattern decomposition of the mean surface air temperature response to an increase of CO 2 is assessed. This decomposition is based on a two-layer global energy-balance model and the hypothesis of separability in space and time. It is shown that this decomposition allows the regional transient warming of a given atmosphere-ocean general circulation model to be well represented. The pattern decomposition is applied to 16 CMIP5 climate models and each of the two retrieved patterns - the equilibrium pattern and the pattern associated with the deep-ocean heat uptake - is described and discussed.

Calcium regulation plays a central role in cardiac function. Several variants in the calcium channel Ca v 1.2 have been implicated in arrhythmic syndromes. We screened patients with Brugada syndrome, short QT syndrome, early repolarisation syndrome, and idiopathic ventricular fibrillation to determine the frequency and pathogenicity of Ca v 1.2 variants. Ca v 1.2 related genes, CACNA1C , CACNB2 and CACNA2D1 , were screened in 65 probands. Missense variants were introduced in the Ca v 1.2 alpha subunit plasmid by mutagenesis to assess their pathogenicity using patch clamp approaches. Six missense variants were identified in CACNA1C in five individuals. Five of them, A1648T, A1689T, G1795R, R1973Q, C1992F, showed no major alterations of the channel function. The sixth C-terminal variant, Ca v α 1c -T1787M, present mostly in the African population, was identified in two patients with resuscitated cardiac arrest. The first patient originated from Cameroon and the second was an inhabitant of La Reunion Island with idiopathic ventricular fibrillation originating from Purkinje tissues. Patch-clamp analysis revealed that Ca v α 1c -T1787M reduces the calcium and barium currents by increasing the auto-inhibition mediated by the C-terminal part and increases the voltage-dependent inhibition. We identified a loss-of-function variant, Ca v α 1c -T1787M, present in 0.8% of the African population, as a new risk factor for ventricular arrhythmia.