Global warming increases lightning activity over Brazil regardless of the trend in cloud ice content simulated by a GCM

<title>Abstract</title> <p> Global warming may modify lightning activity, although projections remain uncertain due to the diversity of parameterizations that emphasize different physical controls on atmospheric electrification, including atmospheric instability, cloud-top height, and ice content. This study projects changes in lightning density over Brazil by the end of the century using observations from the World Wide Lightning Location Network, ERA5 reanalysis, and climate projections from the EC-EARTH3-VEG Global Climate Model (GCM) under intermediate- and high-emission scenarios. Atmospheric predictors physically related to storm electrification were selected based on spatial correlations, skill in reproducing the seasonal cycle of lightning, statistical significance, and performance in simulating observed lightning in multivariate linear regression models. Convective available potential energy, total cloud ice content, convective precipitation rate, and mean sea level pressure emerged as the main controls. Two models were developed: one explicitly including cloud ice content and another using convective precipitation rate and mixed-phase depth as indicators of realized convection and ice formation potential. Both models reproduce the observed spatial and seasonal variability and project a spatially widespread increase in lightning density over Brazil in 2071–2100, with thermal sensitivity ranging from 8 to 11.5% K ^− 1 and absolute changes from 14 to 51%, depending on the predictors and scenario. The Brazilian Amazon shows the largest increases, reaching 9–24% K ^− 1 , thereby increasing the risk of lightning-ignited fires in a forest that is becoming progressively more susceptible to fire. </p>