What is Carbon Dioxide and How is it Produced?

Carbon dioxide, abbreviated as CO2, is a clear gas that does not burn, and in standard temperature and pressure conditions, is stable, inert, and non-toxic. It is an important heat-trapping gas (or greenhouse gas) that comes from the extraction and burning of fossil fuels (such as coal, oil, and natural gas), from wildfires, and from natural processes like volcanic eruptions. Although the gas has now become synonymous with climate change, it also happens to be one of the most important gasses on the earth, as plants use it to produce carbohydrates through a process called photosynthesis. Since humans and animals depend greatly on plants for food, photosynthesis is necessary for the survival of life on earth.

Since the beginning of industrial times (in the 18th century), human activities have raised atmospheric CO2 by 50% – meaning the amount of CO2 is now 150% of its value in 1750. Therefore, CO2 emission control has now been deemed essential for combating climate change as we are pumping out CO2 faster than the planet’s sinks can absorb, tipping the equilibrium, which was once a balanced cycle.

Main sources of carbon dioxide

CO2 comes from both natural and man-made (anthropogenic) sources.

Carbon Dioxide Emissions: Human Sources:

Human CO2 sources are part of our everyday activities and can be categories into the following:

Fossil fuel combustion/use

The largest human source of carbon dioxide emissions is from the combustion of fossil fuels like coal, natural gas and oil. This produces 87% of human carbon dioxide emissions. Burning these fuels releases energy which is most commonly turned into heat, electricity or power for transportation.

Electricity/Heat sector

Electricity and heat generation is the economic sector that produces the largest amount of man-made carbon dioxide emissions. Around the world, this sector relies heavily on coal, the most carbon-intensive of fossil fuels, explaining this sector giant carbon footprint

Transportation sector

The transportation sector is the second largest source of anthropogenic carbon dioxide emissions. This energy-intensive  sector uses petroleum based fuels (gasoline, diesel, kerosene, etc.) almost exclusively to to transport people and goods around the world.

Industrial sector

The industrial sector is the third largest source of man-made carbon dioxide emissions. The industrial sector consists of manufacturing, construction, mining, and agriculture. Manufacturing is the largest of the 4 and can be broken down into 5 main categories: paper, food, petroleum refineries, chemicals, and metal/mineral products. These categories account for the vast majority of the fossil fuel use and CO2 emissions by this sector.

Land use changes

Land use changes are when the natural environment is converted into areas for human use like agricultural land or settlements. From 1850 to 2000, land use and land use change released an estimated 396-690 billion tonnes of carbon dioxide to the atmosphere

Carbon Dioxide Emissions: Natural Sources:

Apart from being created by human activities, carbon dioxide is also released into the atmosphere by natural processes like:

Ocean-atmosphere exchange

This is the largest natural source of carbon dioxide emissions. The oceans contain dissolved carbon dioxide, which is released into the air at the sea surface. Annually this process creates about 330 billion tonnes of carbon dioxide emissions

Plant and animal respiration

Carbon dioxide is a byproduct of the chemical reaction that plants and animals use to produce the energy they need. Annually this process creates about 220 billion tonnes of carbon dioxide emissions

Soil respiration and decomposition

Many organisms that live in the Earth's soil use respiration to produce energy. Amongst them are decomposers who break down dead organic material. Both of these processes releases carbon dioxide as a byproduct. Annually these soil organisms create about 220 billion tonnes of carbon dioxide emissions

Volcanic eruptions

A minor amount carbon dioxide is created by volcanic eruptions, which accounts for 0.03% of natural emissions. Volcanic eruptions release magma, ash, dust and gasses like carbon dioxide.  from deep below the Earth's surface.

Countries That Produce the Most Carbon Dioxide (CO2)

According to the most recent data from the Global Carbon Atlas, the top five countries that have produced in aggregate the most CO2 since the Industrial Revolution are the United States, China, Russia, Germany, and the U.K. However, if you look only at the latest figures, In 2020, the largest emitters in 2020 were in China, the U.S., India, Russia, and Japan.

This is evidence that, in general, developed countries and major emerging economies lead in total carbon dioxide emissions. However, while on one hand developed nations typically have high carbon dioxide emissions per capita, some developing countries lead in the growth rate of carbon dioxide emissions. These uneven contributions to the climate crisis are at the core of the challenges the world community faces in finding effective and equitable solutions to global warming.