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Hydrogen (H2) is considered a promising fuel to contribute to net-zero carbon emission goals. While hydrogen itself is not a greenhouse gas, leakage of hydrogen fuels causes indirect warming due to hydrogen’s influence on methane, tropospheric ozone, and stratospheric water vapor, with the methane term dominating the impact. Some studies consider a simple four-equation box model to explore the climate consequences of leakage from hydrogen fuel use relative to methane, while others have employed much more detailed global photochemical models. Here we use a comprehensive photochemical box model including 66 reactions to show and quantify how the analogous four-equation system is missing a critical OH feedback, leading it to overestimate the time-integrated methane response to a pulse of hydrogen by over 100%. We estimate a hydrogen global warming potential (GWP) relative to carbon dioxide of 28−11+18 on the 20-year time horizon and 10−4+7 on the 100-year time horizon based on the 66-reaction model and information from the literature. GWPs provide a measure of the relative global warming impact of emission of one gas compared to a selected reference gas per unit mass emitted. While CO2 is generally chosen for the reference, any gas can be used. We present the GWP of H2 using CH4 as the reference, as this choice cancels out some uncertainties that are common to both H2 and CH4. The GWP for H2 relative to CH4 from fossil fuel sources is 0.35−0.06+0.13 on time horizons beyond 15 years; put differently, we find that relative to an equivalent mass of emission of fossil CH4, hydrogen emission has a climate impact about three times smaller. These global warming potentials underscore that hydrogen leakage does contribute to climate change, emphasizing the importance of limiting both hydrogen and methane leakage if global net-zero greenhouse gas emissions are to be achieved by 2050.

Abstract Following the Hunga Tonga–Hunga Ha'apai (HTHH) eruption in January 2022, significant reductions in stratospheric hydrochloric acid (HCl) were observed in the Southern Hemisphere mid‐latitudes during the latter half of 2022, suggesting potential chlorine activation. The objective of this study is to comprehensively understand the loss of HCl in the aftermath of HTHH. Satellite measurements and a global chemistry‐climate model are employed for the analysis. We find strong agreement of 2022 anomalies between the modeled and the measured data. The observed tracer‐tracer relations between nitrous oxide (N2O) and HCl indicate a significant role of chemical processing in the observed HCl reduction, especially during the austral winter of 2022. Further examining the roles of chlorine gas‐phase and heterogeneous chemistry, we find that heterogeneous chemistry emerges as the primary driver for the chemical loss of HCl, and the reaction between hypobromous acid (HOBr) and HCl on sulfate aerosols is the dominant loss process.

Therapists’ responses to challenging therapy situations on the Facilitative Interpersonal Skills (FIS) performance task are a significant predictor of therapists’ differences in treatment outcomes. The aim of this study was to assess whether the complexity of the therapy situation influenced the facilitative interpersonal skills of trainees. Trainee therapists (n=46) participated in an experiment in which they responded to a set of challenging and benign (i.e., non-challenging) video vignettes of therapy situations of the FIS performance task. Their responses were video recorded and coded by four independent raters. Results showed that trainees scored significantly higher on the FIS performance task responding to benign therapy situations than responding to challenging situations. This is the first study to investigate difficulty of therapy situations as a potential predictor or trainees interpersonal skills. Further research is needed to replicate these results in a larger sample.

Self-determination (SD) is linked to autonomy and better adult outcomes. Adults with autism spectrum disorder (ASD) are often less independent than cognitively matched peers. Given the frequency with which depression co-occurs in ASD and the established association between depression and SD, we sought to evaluate the influence of both ASD severity and depression on SD among cognitively able emerging adults with ASD. Emerging adults (n = 59) with ASD completed measures of SD, ASD severity, and depression. Both ASD severity and depression were moderately correlated with SD (r = - 0.473; - 0.423, respectively) and with each other (r = 0.625). After controlling for ASD severity, depression did not significantly predict SD. Strengthening SD should be considered in programming to promote independence., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)