Analysis of Near-Surface Air Temperature Trends in Brazil Region Using Meteorological Station Data, ERA5 Reanalysis, and CMIP6 Models

In view of global climate change, studies on long-term changes in Near-Surface Air Temperature (NSAT) in the Brazil region are highly relevant. Climate warming requires the government to develop various adaptation strategies to these changes in order to maintain marine and terrestrial ecosystems in a stable state. Pearson correlation analysis, with significance assessment of the obtained results, was used to analyze NSAT data from 39 weather stations, along with the ERA5 reanalysis dataset and 33 CMIP6 models, for the different SSP scenarios of greenhouse gas emissions in the Brazil region (10° N–40° S; 75–25° W). The increase in NSAT of the Brazil region for 1964–2023 was 0.4 ± 0.2 °C based on meteorological stations and 0.3 ± 0.1 °C based on the ERA5 reanalysis. NSAT by ERA5 data changed little from 1940 to 1970, after which a relatively rapid increase began at a rate of +0.18 °C/10 years. The increase in NSAT for the period 1940–2023 was 0.66 ± 0.17 °C based on the CMIP6 model ensemble. The CMIP6 models show the increase in the average NSAT across the region of 0.75–1.08 °C from 1994–2023 to 2024–2053. The average NSAT in the region under the SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios shows an increase of 1.05, 1.89, 2.75, and 3.53 °C by the end of the 21st century, respectively. Moreover, NSAT over land in the study region is increasing faster than over the ocean. According to the CMIP6 ensemble, NSAT over land in the Brazil region increased by an average of 0.6–1.0 °C from 1940–1969 to 1994–2023, while over the ocean near the Brazilian coastline it increased by approximately 0.5 °C. From 1994–2023 to 2070–2099, the projected warming over land is expected to be 1.0–1.4, 1.6–2.6, 2.4–3.8, and 3.2–5.0 °C for the SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, respectively. Over the ocean, however, the estimated warming is substantially smaller—from 0.8 to 2.8 °C, depending on the SSP scenario, which may be explained by the stabilizing role of the ocean.