Assessing the Impacts of Climate Change on Rice Production in Rio Grande do Sul, Brazil: A 24-Year Remote Sensing Analysis

Climate change is increasingly disrupting agricultural systems worldwide, and Brazil’s rice production is no exception. The state of Rio Grande do Sul, which accounts for 70% of the country’s rice output, has been experiencing growing climate variability, including droughts, floods, heatwaves, and irregular rainfall. Despite its strategic importance, few spatially explicit studies have evaluated the long-term effects of climate change on rice-growing areas in the region. Therefore, this study assesses the impacts of climate change on rice production in Rio Grande do Sul by analyzing 24 years (2001–2024) of satellite-based precipitation and land surface temperature (LST) data. Temporal and spatial changes in three key climate extreme indicators were examined: days with LST above 35 °C, heavy rainfall events above the 95th percentile, and prolonged dry spells (consecutive dry days, CDD). In addition, Mann-Kendall trend analysis and Sen’s slope estimator were applied to detect trends in mean daytime and nighttime LST. The results reveal a statistically significant increase in nighttime LST, while daytime LST remained stable. In the last 12 years, CDD decreased across 83% of the territory, and 97.63% of the area recorded positive rainfall anomalies, suggesting a shift toward a wetter climatic regime. There was also a notable increase in extreme rainfall frequency, particularly in the southern Campanha subregion. Interestingly, although the frequency of days with LST > 35 °C decreased in 67.06% of the territory, 69.5% of rice fields are located in areas where this frequency increased, indicating that thermal stress has been redistributed toward zones of high agricultural relevance. Additionally, 88.7% of rice fields are exposed to more frequent extreme rainfall, and 28.6% to extended dry spells. The eastern portion of the study area emerged as a critical hotspot, where rice fields are increasingly exposed to all three types of extreme climate events—heat, drought, and intense rainfall. These findings underscore the emergence of new climate risk zones and emphasize the urgent need for targeted adaptation strategies, such as the improvement of early warning systems, promotion of climate-resilient rice varieties, optimization of water resource management, support for farm-level planning and technical assistance, and the preservation and restoration of natural ecosystems, to protect rice production and ensure food security in a changing climate.