Spatial and seasonal asymmetries in temperature and precipitation changes across the tropics and subtropics

Abstract Quantifying seasonally varying changes in temperature and precipitation is crucial for understanding the environmental and socioeconomic impacts of climate change. Using the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5th Generation (ERA5) dataset for 1979–2020, we analyze changes in the mean, variance, and skewness of near-surface temperature and precipitation in the tropics and subtropics in both hemispheres. Results show a global mean warming rate of $$0.23^{\circ }$$ C per decade, with stronger warming over land than ocean and a pronounced amplification in the Northern Hemisphere subtropics relative to the tropics. Precipitation has increased globally at a rate of 9.71 mm per decade, with larger increases over the tropics and a clear land-ocean contrast, characterized by increases over oceans and decreases over land, reflecting combined thermodynamic and dynamical influences. Seasonally, the fastest rates of both temperature and precipitation increase occur in boreal autumn, followed by winter, spring, and summer. In addition, both the variance and skewness of temperature and precipitation decrease in the far eastern tropical South Pacific during 2000–2019 relative to 1980–1999, indicating a reduction in variability and occurrence of extremely warm and wet events. These results highlight substantial spatial and seasonal asymmetries in temperature and precipitation changes and provide new insights into shifts in regional climate variability and extremes.