CO2 (carbon dioxide) is a trace gas in the atmosphere, with current values of around 370 parts per million by volume (ppm). As a by-product of aerobic respiration, CO2 is produced. Photosynthesis is the process through which plants absorb CO2 and release oxygen. Seasonal variations in atmospheric CO2 are caused by changes in the worldwide balance between photosynthesis and respiration. Despite relatively modest quantities in comparison to nitrogen or oxygen, CO2 plays an important part in the Earth's life cycle and climate management. This article will explain to you the Carbon dioxide (CO2) which will be helpful in Environment Subject preparation for the UPSC Civil Service Exam.

What is Carbon Dioxide (CO2)?

• Carbon dioxide (CO2) is a colorless and odorless gas that occurs naturally.
• It has a sublimation boiling point of 70°C, a vapor density of 1.53.
• Carbon dioxide is a greenhouse gas that plays a vital part in regulating the earth's temperature.
• Carbon dioxide is water soluble and can be found in groundwater, rivers and lakes, ice caps and glaciers, and ocean.

Functions of Carbon Dioxide (CO2)

• Carbon is the major component of proteins, lipids, nucleic acids, and carbohydrates. The molecular structure of carbon allows it to establish bonds with a wide range of elements in a variety of ways.
• The carbon cycle displays the movement of carbon, both living and non-life, throughout the planet.
• The principal greenhouse gas emitted by human activity is carbon dioxide (CO2).
• Carbon dioxide is required for two fundamental plant and animal processes: Photosynthesis and Respiration.
• Photosynthesis is when green plants convert carbon dioxide and water into food molecules like glucose and oxygen. The photosynthetic reaction is as follows:

6CO2 + 6H2O = C6H12O6 + 6O2

• Respiration - The transfer of oxygen from the outside environment to the cells within tissues, as well as the removal of carbon dioxide in the opposite direction to the environment.
• Carbon dioxide is the body's basic hormone. It has many functions in the body, including oxygen transport to cells, blood pH adjustment, and so on.

Carbon Cycle

• The principal greenhouse gas emitted by human activity is carbon dioxide (CO2).
• As part of the Earth's carbon cycle (the natural circulation of carbon among the atmosphere, seas, soil, plants, and animals), carbon dioxide is naturally present in the atmosphere.
• Carbon, primarily in the form of carbon dioxide (CO2), is present in the atmosphere.
• A continual exchange of carbon between the atmosphere and organisms is referred to as the carbon cycle.
• The process of photosynthesis transports carbon from the atmosphere to green plants and ultimately to organisms.
• It returns to the atmosphere through the processes of respiration and decomposition of dead organic stuff.
• The carbon cycle is a short-term cycle.
• Some carbon enters a long-term cycle as well. It builds up as undigested organic waste in peaty layers of marshy soil or as insoluble carbonates in bottom sediments of aquatic systems, taking a long time to disintegrate.
• Such carbon can be buried for millions of years in deep oceans until geological movement lifts the rocks above sea level.
• When these rocks are subjected to erosion, carbon dioxide, carbonates, and bicarbonates are released into streams and rivers.
• Coal, oil, and natural gas, for example, are organic substances that were buried before they could disintegrate and were subsequently changed into fossil fuels by time and geological processes.
• When they are burned, the carbon stored in them is released as carbon dioxide into the environment.
• Human activities disrupt the carbon cycle by increasing CO2 levels in the atmosphere and decreasing natural sinks, such as deforestation, that remove CO2 from the atmosphere.
• While CO2 emissions come from a range of natural sources, human-caused CO2 emissions are to blame for the rise in the atmosphere since the industrial revolution.

Sources of CO2 Emission

• Carbon dioxide emissions come from both natural and anthropogenic sources.
• Decomposition, ocean release, and respiration are all-natural sources.
• Human causes include cement manufacturing, deforestation, and the combustion of fossil fuels.
• Human sources of carbon dioxide emissions have been increasing since the Industrial Revolution.
• Coal, natural gas, and oil combustion account for 87 percent of all human-produced carbon dioxide emissions.
• The remaining comes from forest clearing and other land use changes (9%), as well as some industrial operations like cement production (4%)

Respiration and Decomposition

• Respiration and decomposition are natural processes in which carbon dioxide and oxygen are exchanged between the blood of animals and the environment.
• Animals and plants release carbon dioxide into the atmosphere through respiration, which occurs at the cellular level.
• Organic species decay by the same process of respiration. Both water and carbon dioxide are released into the atmosphere as a result of this process.
• This is because decomposing bacteria decompose both plants and other living organisms, releasing CO2 into the atmosphere, where it can be used by green plants to perform photosynthesis.

Weathering of Carbonate Rocks

• Carbonate Rocks act as a storage of Carbon Dioxide in the rocks.
• During rains limestone becomes exposed to the atmosphere over time.
• This is because when CO2 dissolves in water, carbonic acid is generated.
• Carbonate rocks are dissolved, and more carbon dioxide is released into the atmosphere.

Burning of fossil fuels

• Deforestation, coal burning, gasoline, and gas production all contribute to at least 87 percent of the CO2 gas emitted into the atmosphere.
• Deforestation influences CO2 levels in the atmosphere in more significant ways than simply releasing extra carbon dioxide into the atmosphere by burning coal and trees.
• The most significant source of CO2 emissions in the atmosphere is the combustion of fossil fuels for energy.
• Fossil fuels account for three-quarters of human CO2 emissions, according to UNEP (United Nations Environment Programme).
• However, the energy derived from the combustion of fossil fuels is required for the generation of heat, electricity, and power in industries such as manufacturing, construction, and residential and commercial buildings.
• Oil, coal, and natural gas are the most common fossil fuels used in energy production.
• These fossil fuels are responsible for 20%, 43%, and 36% of carbon emissions, respectively.

Transport sector

• Another major source of carbon emissions in the atmosphere is the transportation industry.
• Freight, autos, and light-duty vehicles account for around 72 percent of the carbon dioxide emissions associated with the transportation industry, with freight, automobiles, and light-duty trucks being major emitters.
• Global aviation and maritime shipping, in addition to road vehicles, contribute to carbon dioxide emissions in the atmosphere.
• Marine shipping accounts for 14% of all carbon dioxide emissions from transportation, whereas worldwide aviation accounts for around 11%.

Other Sources

• Industrial processes account for roughly 20% of CO2 emissions from fossil fuels.
• Construction, agriculture, mining, lithium extraction, agriculture, and manufacturing are among these processes.
• Manufacturing, on the other hand, is the most substantial contributor of the four.
• Several operations, including the manufacture and use of mineral goods such as cement, the manufacturing of metals such as iron and steel, and the creation of chemicals, produce CO2 emissions through chemical reactions that do not entail combustion.

Carbon dioxide as a Green House Gas (GHG)

• Carbon dioxide and other pollutants together referred to as greenhouse gases, are emitted into the atmosphere as a result of both human and natural sources.
• The greenhouse effect occurs when these gasses concentrate in the atmosphere and generate an insulating effect around the globe.
• They allow the sun's rays to enter, but when they bounce off the globe and back into space, the greenhouse gasses reflect them back to Earth.
• The global temperature rises as a result of this process, resulting in a complicated chain of events known as global climate change.
• Global climate change not only raises temperatures but also alters the planet's overall weather patterns and climate.

Effects of CO2 Emission

Climate Change

• The rise in sea level is one of the most obvious effects of global climate change.
• The polar ice caps melt when the global average temperature rises. As a result of the melting, the overall sea level rises, potentially causing floods in coastal areas.
• It also has the potential to aggravate the effects of storms in coastal locations.
• Hurricanes, for example, are affected by global climate change in terms of their development and severity, allowing them to occur with more regularity and force.
• Hurricanes form over warm tropical waters, and rising water temperatures aid in the storm's rapid intensification.
• Changes in sea temperature have an impact on aquatic life below the surface as well as lead to fish migration to cooler places.

Health

• CO2 exposure can have a range of health consequences.
• Headaches, dizziness, restlessness, tingling or pins-and-needles sensations, difficulty breathing, sweating, weariness, increased heart rate, high blood pressure, coma, suffocation, and convulsions are some of the symptoms that might occur.
• As carbon dioxide levels grow, breathing becomes increasingly difficult.

Environment

• Carbon dioxide emissions have an impact on plant growth, despite the fact that it is essential for growth.
• These researchers believe that there is too much carbon dioxide in the atmosphere, resulting in thick leaves.
• These thick leaves are ineffective in reducing carbon dioxide levels in the atmosphere, which can have disastrous consequences.

Converting CO2 to Methane

• Indian scientists recently developed a photochemical technology (Photocatalyst) for converting carbon dioxide (CO2) into methane (CH4).

Photochemical Technique

• A photochemical technique is a chemical process that is triggered by the absorption of light energy.
• A polymer has been created that absorbs visible light and catalyzes the CO2 reduction reaction.
• The majority of catalysts have toxic and costly metal equivalents.
• To circumvent this limitation, scientists developed a metal-free porous organic polymer.
• Solar light is used as a renewable source of energy in the photochemical process of CO2 reduction.
• CO2 can be reduced in a variety of ways, including photochemical, electrochemical, photoelectrochemical, photothermal, and other methods.

Mechanism

• The Conjugated Microporous Polymer (CMP) is a substance found in the catalyst.
• Due to its strong CO2 intake capability at ambient temperature, it can ingest CO2 onto its surface and convert it to methane as a value-added product.

Significance

• Methane is a value-added commodity that has a wide range of applications as the cleanest-burning fossil fuel and as a hydrogen carrier in fuel cells.
• It is also the principal component of natural gas, and it has the potential to replace coal in the generation of power.

Steps to Reduce CO2 Emission

• Governments must work together to keep global warming below 2 degrees Celsius over pre-industrial levels, according to the 2016 Paris Climate Agreement.
• However, in order for this to happen, we must cut CO2 emissions and remove more carbon from the atmosphere.
• Many climate models predict that by 2050, we will need to remove or store billions of metric tonnes of CO2 while reducing our carbon footprint.
• Various initiatives, ranging from land management to the use of new technology, can be used to remove carbon from the atmosphere.
• However, it remains to be seen if these climate control models will be able to remove carbon dioxide from the atmosphere at the required scale in the future decades.
• Increasing forest cover - Trees store the carbon extracted from the atmosphere in addition to naturally taking CO2 from the air through photosynthesis.
  • As a result, we may use the power of photosynthesis to mitigate climate change by restoring, expanding, and maintaining forests.
• Increasing agriculture cover - Agricultural land is so large, that even a modest increase in carbon stored in the ground per acre can have a big impact. Farmers benefit from soil carbon because it improves crop yields and soil health.
• Direct carbon capture - Chemically scraping CO2 from ambient air and storing it in long-lived products is referred to as direct air capture.
  • This method is comparable to that used to absorb pollutants from power plants and industrial sites.
  • Direct air capture technology, on the other hand, takes excess carbon from the atmosphere directly.

Conclusion

While carbon dioxide is necessary for plant growth and food production, too much of it in the atmosphere can lead to health problems, habitat damage, and drastic climate change. As a result, even as governments seek to remove excess CO2 from the air, we all have a responsibility to minimize our carbon dioxide emissions.