Background and Method: Urban traffic and air pollution remain strongly interconnected challenges for big cities. In Jakarta, transportation activity remains one of the primary contributors to carbon dioxide (CO₂) emissions and urban heat stress, worsened by high-density land use and limited integration of public transportation. The COVID-19 pandemic temporarily transformed these dynamics through the policy of social mobility restriction; this study therefore aims to assess how changes in traffic volume affect CO₂ intensity and thermal level across different traffic policy and behavioral contexts. This study examines the relationship between urban traffic performance, CO₂ intensity, and air temperature in Jakarta from 2021 to 2023, during both pre and post social mobility restriction periods. Real-time navigation data were logged using U-Blox F9P and M8T GNSS receivers connected with environmental sensors along two major Jakarta routes. Over 75,000 data loggings were analyzed using spatial mapping, temporal profiling, and regression modelling to analyze interactions among the vehicle speed, CO₂ level, and temperature s. The analysis applied standardized thresholds for urban air quality (380 ppm) and thermal comfort (21.6–31.6 °C) to evaluate environmental degradation under varying traffic conditions. Results: Across the three-year study, mean CO₂ increased by 185.29 ppm (+36.8 %), air temperature by 1.74 °C (+4.9 %), and mean vehicle speed dropped by 4.93 km/h (–25.1 %). Even during the social mobility restrictions, CO₂ and temperature levels exceeded acceptable thresholds, indicating continued anthropogenic burdens beyond traffic. Regression and spatial analyses showed that reduced traffic speeds are strongly associated with increased CO₂ concentrations and temperatures, with high peak concentrations occurring in commercial, industrial, and mixed-use areas. Conclusions: The findings indicate that short-term interventions, such as the COVID-19 pandemic's social mobility restriction policy, can temporarily reduce traffic congestion but do not address the primary causes of carbon emissions and heat stress. Persistent CO₂ and temperature exceedances highlight the need for integrated strategies targeting transport, land use, energy, and industrial activities to effectively improve air quality and climate resilience in Jakarta. These results imply that focusing solely on the transportation sector is insufficient; comprehensive policy coordination is essential for reducing urban emissions and thermal stress. The study also demonstrates the value of GNSS-based real-time monitoring as an effective tool for informing integrated approaches to low-carbon mobility, spatial planning, and climate-resilient city management. © The Author(s) 2026.