CO2 emissions from China, the United States, India, Russia, Japan, Germany, Iran, South Korea, Indonesia, and Saudi Arabia have grown from 13,000 Mt to 23,200 Mt over the past 20 years (Figure 1). Japan’s CO2 emissions increased from 430 Mt in 1965 to 1300 Mt in 2008, then decreased to 1200 Mt. CO2 in Germany, reached a maximum of 1120 Mt in 1973, and then slowly declined to 680 Mt in 2019. Iran, South Korea, and Indonesia have similar trajectories of CO2 emission changes, growing from 200 Mt to about 650 Mt. Saudi Arabia’s CO2 emissions increased from 60 Mt in 1965 to 580 Mt in 2019. The United States had the highest values with its CO2 emission per capita declining from a peak of 22.5 t in 1973 to 15.1 t in 2019. Saudi Arabia has replaced the United States as the country with the highest CO2 emissions per capita since 2011, and its value now stands at 17 t. CO2 emission per capita in Russia decreased from 15 t in the 1990s to 10 t in 2019. CO2 emissions per capita in Iran and China grew rapidly to 8 t and 7 t, respectively. The cumulative values of Saudi Arabia, Russia, Germany, Japan, and South Korea were 739 t, 707 t, 635 t, 476 t, and 369 t, respectively. The CO2 emissions show decreasing trends in the United States, Japan, and Germany, and will reach 4510 Mt, 1078 Mt, and 673 Mt, respectively (Figure 6). For South Korea and Saudi Arabia, the CO2 emissions are expected to continue to increase, reaching 755 Mt and 753 Mt, respectively, in 2030. The CO2 emissions trends in middle and low-income countries are also di erent (Figure 7). For Russian Federation, the CO2 emissions will remain at around 1500 Mt. China’s CO2 emissions will grow at a slower rate due to its improvement in energy effciency and deployment of renewable energy. The estimation of China’s CO2 emissions will reach a maximum of around 12,500 Mt in 2030. The CO2 emissions of India, Iran, and Indonesia will continue to grow rapidly, reaching 4294, 969, and 874 Mt, respectively, in 2030.