The important source of carbon dioxide (CO2) emission is identified to be energy usage, which the demand is gradually increasing. Currently, many people are exposed to increasing temperatures, which affects to health, environment, and quality of life. Moreover, there are many worries about its continuously increasing trend. This work is interested in studying the association between the annual CO2 emission and the annual mean temperature in Thailand. At a confidence interval of 90%, a statistically significant association between the annual CO2 emission and the annual mean temperature was observed. The appropriate predictive equation represented that the CO2 emission at 0.481 M ton increased the annual mean temperature by about 1°C. The results are useful for planning the reduction of CO2 emissions in Thailand. Fascinatingly, the largest source comes from electricity production, and the most significant energy type is finished oil. Therefore, they should be controlled as the priority. Integrated methods are considered as more efficient strategies for the CO2 crisis.