Pollution and its impact upon the environment is arguably the most important challenge currently facing the world. Pollution is not a single substance, but thousands of unwanted substances that can be released into the environment through human activity and which then degrade the quality of air, water, soil, or other ecological factors. Pollution can affect humans, causing or exacerbating health problems including allergies, asthma, cancer or heart disease, and even death. It can also harm flora and fauna both in the wild, which can damage entire ecosystems, and in agricultural settings, which puts mankind's food supply at risk.
Because pollution takes many different forms, determining which country is the greatest polluter in the world is a complex task (although the most polluted countries are somewhat easier to identify). However, as CO₂ is the leading greenhouse gas and the main cause of global warming, making it arguably the most important pollutant in the world, CO₂ emissions are a wise place to start. Which countries release the highest CO₂ emissions depends upon whether one measures total emissions or emissions per person, also known as per capita.
10 Countries with Highest Total CO₂ emissions in 2019 (Global Carbon Project):
| Rank | Country | CO₂ (million tons) | CO₂ (tons) |
|---|---|---|---|
| 1 | China | 10,666 | 10,665,904,000 |
| 2 | United States | 4,716 | 4,715,568,000 |
| 3 | India | 2,444 | 2,443,888,000 |
| 4 | Russia | 1,576 | 1,575,520,000 |
| 5 | Japan | 1,030 | 1,029,584,000 |
| 6 | Iran | 744 | 743,792,000 |
| 7 | Germany | 645 | 644,864,000 |
| 8 | Saudi Arabia | 627 | 626,544,000 |
| 9 | South Korea | 601 | 600,896,000 |
| 10 | Indonesia | 590 | 589,904,000 |
10 Countries with Highest CO₂ emissions Per Capita in 2019 (Climate Watch Data):
| Rank | Country | CO₂ per Capita (tons) |
|---|---|---|
| 1 | Qatar | 40.62 |
| 2 | Trinidad and Tobago | 28.95 |
| 3 | Mongolia | 27.50 |
| 4 | Brunei | 22.98 |
| 5 | Kuwait | 22.97 |
| 6 | Bahrain | 20.98 |
| 7 | Sao Tome and Principe | 18.16 |
| 8 | Australia | 16.34 |
| 9 | United States | 16.01 |
| 10 | Kazakhstan | 15.98 |
Global warming and its impact
Global warming is an increase in the earth's atmosphere caused by elevated levels of greenhouse gases: carbon dioxide (CO₂), chlorofluorocarbons (CFCs), and other airborne pollutants. Greenhouse gases trap heat in the atmosphere, which amplifies humankind's ecological footprint and triggers climate change in the form of shifted weather patterns, melting ice caps and sea-level rise, greater instances of extreme weather (floods, droughts, storms, etc.) and extreme stress on flora and fauna that cannot adapt to (or migrate away from) their morphing ecosystem quickly enough.
Because of the potential effects of climate change, many nations are making a concentrated effort to shrink their carbon footprint and reduce emissions of CO₂ and other greenhouse gas pollutants. Carbon dioxide (CO₂) is the most prevalent (though not the most potent) greenhouse gas. CO₂ is emitted by the combustion of fossil fuels—primarily oil, natural gas, and coal—which are heavily utilized by industries including transportation (vehicle fuel), energy (burned to create electricity), and manufacturing (burned during metalworking and other processes).
In an effort to curb CO₂ emissions, many of the world's nations are working to [become greener](world's greenest nations) and reduce their oil consumption by investing heavily in renewable energies such as solar power and wind farms, as well as electric vehicles and greener manufacturing processes. Many countries are also seeking to simply reduce their overall energy consumption via upgraded infrastructure and other means.
Despite these efforts, pollution is a major concern in many countries, from the developing countries of eastern Asia to the United States, one of the most highly developed countries on Earth. One of the organizations tasked with tracking global CO₂ emissions is the European Commission and Netherlands Environmental Assessment Agency, whose EDGAR database includes data from 1970 to current times. Another reputable source is the Integrated Carbon Observation System's Global Carbon Project (GCP), whose data was utilized in the creation of this page.
Air Quality Index
Another method of measuring pollution is a country's overall air quality, measured by its PM2.5 concentration. PM2.5 is an air pollutant that is a concern for people's health at high levels. These particles reduce visibility and make the air appear hazy. The Air Quality Index (AQI) measured significant air pollutants, such as PM2.5 and others, including ground-level ozone, carbon monoxide, and sulfur dioxide. Based on the AQI, many Asian nations rank among the world's most polluted countries, including Bangladesh, Pakistan, Mongolia, Afghanistan, India, Indonesia, Bahrain, Nepal, Uzbekistan, and Iraq.
Additional forms of pollution: microplastics, light pollution, and noise pollution
Air pollution may earn the majority of the attention, but it is far from being the only form of pollution. For example, researchers are becoming increasingly aware of the presence of microplastics—microscopic bits of plastic, usually the remains of plastic grocery bags—in everything from groundwater to the bodily tissues of aquatic animals. Many countries also struggle with plastic pollution on a macro scale, as do the oceans, where massive patches of floating garbage have been discovered.
While most pollutants are physical materials—such as gaseous emissions from fossil-fuel-burning power plants or microplastics created by the degradation of plastic trash—some are less tangible. Examples of non-material forms of pollution include "light pollution," which is caused by excess nighttime illumination (especially in urban areas) and can upset the circadian cycles of humans, plants, and animals. Another is "noise pollution", which can lead to a myriad of significant health problems for humans, whales, and other marine animals.
Most Environmentally Friendly Countries
The Environmental Performance Index (EPI) compares and analyzes environmental performance for 180 countries. Each country is ranked on performance indicators across ten categories covering environmental health and ecosystem vitality. Indicators include air quality, PM2.5 exposure, ozone exposure, sanitation, and drinking water. According to the EPI, the most environmentally friendly countries tend to be those in the European Union, such as Denmark, Luxembourg, Switzerland, the United Kingdom, France, Austria, Finland, Sweden, Norway, and Germany.
The EPI helps countries understand how effective their current environmental policies are and the areas they need improvement on. Eco-friendly practices and policies are found in goods and services, laws, transportation, and guidelines across all industries. Implementing eco-friendly products, practices, and processes help preserve the natural environment, conserve natural resources like water and energy, and prevent air, water, and land pollution.