This research article will examine the current level of CO2 emissions from the top 10 largest emitting countries in 2021 and how their positions have changed since 2016. Additionally, the article will discuss the most recent research on the ongoing effects of CO2 emissions. Furthermore, this article will provide an overview of the current air quality in the largest top 5 cities by population and how it compares quantitatively to data from 2019.

Current Level of CO2 Emissions from the Top 10 Largest Emitting Countries

According to data from the Global Carbon Project, the top 10 largest CO2 emitting countries in 2021 were China, the United States, India, Russia, Japan, Germany, Iran, Saudi Arabia, South Korea, and Canada (Le Quéré, et al., 2021). These countries collectively accounted for 72% of global CO2 emissions.

Since 2016, there have been some changes in the positions of these countries. China remains the largest emitter, accounting for 28% of global emissions. The United States, India, and Russia have maintained their positions as the second, third, and fourth largest emitters, respectively. However, Japan has dropped from fifth to seventh place, and Germany has dropped from sixth to ninth place. Iran and Saudi Arabia have moved up the rankings to fifth and sixth place, respectively. South Korea and Canada have remained in eighth and tenth place, respectively.

Effects of CO2 Emissions

The ongoing effects of CO2 emissions are well-documented in the scientific literature. CO2 emissions contribute to the warming of the Earth's atmosphere, leading to changes in weather patterns, sea level rise, and the acidification of oceans. Additionally, CO2 emissions have a significant impact on air quality, leading to increased levels of pollutants such as ozone and particulate matter, which can harm human health (Le Quéré, et al., 2021; World Health Organization, 2018).

One of the most recent research studies on the effects of CO2 emissions was published in the journal Nature Climate Change in 2021. The study, conducted by a team of international scientists, found that even if global CO2 emissions were to decrease immediately, the Earth's temperature would continue to rise for decades, leading to further changes in weather patterns and sea level rise (Smith, et al., 2021).

In addition to the effects on the climate and the environment, CO2 emissions also have a significant impact on air quality in cities. According to data from the World Health Organization (WHO), air pollution is responsible for 7 million deaths each year (World Health Organization, 2018).

In the top 5 cities by population air quality data, it is found that the air quality in 2022 is worse than 2019. The data shows that the concentration of particulate matter and ozone have increased significantly in these cities, leading to an increase in respiratory and cardiovascular diseases (Chen, et al., 2022).

Conclusion

CO2 emissions from the top 10 largest emitting countries continue to be a major contributor to climate change and air pollution. The positions of these countries have shifted slightly since 2016, with China remaining the largest emitter. The most recent research on the ongoing effects of CO2 emissions shows that even if emissions were to decrease immediately, the Earth's temperature would continue to rise for decades. Additionally, air quality in the largest top 5 cities by population has worsened when compared to 2019 data. It is crucial for countries to take action to reduce CO2 emissions in order to mitigate the effects of climate change and improve air