he people who want to sequester carbon dioxide (CO2) don't understand the biosphere. Carbon and oxygen are two of the most important elements for biological life. 65% of the human body is oxygen and 18.5% is carbon. Plants are carbon structures with the percentage of carbon varying according to the type of plant.
The CO2 oxygen cycle is critical to the functioning of the biosphere. Animals exhale CO2 which plants then use to produce the molecules such as sugars and starches that animals use for food. Plants release oxygen into the air which animals inhale and combine with the carbon compounds to grow or perform various body functions.
CO2 is a major source of that carbon that provides the structure for plants. Absorbing CO2 through the leaves allows plants to use their roots for water and minor nutrients, particularly during the initial growth when they don't have extensive root systems. Some plants grow better as the amount of CO2 in the air increases. Some greenhouses use CO2 enrichment equipment to add CO2 to improve plant growth.
Humans are already removing large amounts of carbon from the environment through such actions as construction of wooden buildings and making paper. Much paper and plant wastes are buried in landfills making the carbon unavailable to become part of plants.
The combustion of fossil carbon fuels offsets the removal of carbon from the environment and increases the planet's ability to grow more plants. Adding carbon to the ground to replace carbon in harvested plants isn't as practical as adding carbon to the air in the form of CO2.
Plants are normally thought of in terms of their biological function, but they have an inportant physics function. Plants are the original solar energy storage devices. Globally plants convert huge amounts of solar radiation into the chemical bonds of complex carbon molecules. This process reduces the amount of solar energy converted to heat energy.
The molecules plants produce can be extremely long lived. If fossil fuels are ancient plant wastes as is commonly believed, the combustion of fossil fuels releases solar energy stored millions of years ago.
Each CO2 molecule contains 2 oxygen atoms which are essential to animal life because animals breathe oxygen. Burying oxygen would reduce the amount available for humans to breathe and adversely affect human health.
A better way to "get rid" of CO2 would be to encourage plant growth to return the oxygen to the air humans breathe. For example, power plants that produce CO2 could have attached greenhouses to recycle the CO2 into oxygen for humans to breathe and plants to convert to food or fuel.