Abstract
<title>Abstract</title> <p> The Pantanal biome has been undergoing accelerated microclimatic transformations marked by progressive warming, aridification, and increased atmospheric pollution-factors that compromise ecosystem resilience and public health. In this context, this study aimed to quantify trends in air temperature, relative humidity, and fine particulate matter (PM <sub>2.5</sub> ) concentrations from 2000 to 2024 across three analytical scales: the Pantanal biome, the municipal area of Cáceres, and the urban perimeter of Cáceres, in Mato Grosso, Brazil. Air temperature and relative humidity were obtained from ERA5-Land reanalysis data, and particulate matter was derived from MODIS sensor products. The results indicate a 9.4% increase in mean annual temperature (from 25.52 to 27.96°C), whereas relative humidity declined by 16.7% (from 72.61% to 60.55%). Extreme PM <sub>2.5</sub> pollution episodes were identified in 2005, 2007, and 2020, with peaks exceeding 300 µg m <sup>− 3</sup> . These findings reveal a thermo-pollutant dynamic in which pronounced warming and elevated particulate concentrations act synergistically, intensifying thermal stress and degrading air quality. Over the 24-year period analysed, a growing trend of this interaction was observed, characterizing a new and critical environmental condition for the Pantanal and Cáceres, with serious implications for human health and ecological integrity. </p>