Carbon dioxide is a necessary element for photosynthesis to occur. All plants need to photosynthesize to survive and produce food, particularly glucose. Carbon dioxide is used by plants along with water, H₂O, during photosynthesis to create Glucose, which is C₆H₁₂O₆, a type of sugar. Sugars such as glucose are essential for providing food for all of Earth's plants and animals.  In short, plants need carbon dioxide to survive, and animals & human need plants to survive. Photosynthesizing plants is the start of the flow of energy through all of Earth's food chains and carbon dioxide is crucial to this process.

Carbon dioxide is the ultimate product of fossil fuel combustion as well as many other manmade and natural activities on the earth. Gone are the days when carbon dioxide all around us was in its balanced concentration as it is increasing due to various reasons. Much concern in the form of increasing global temperature (Greenhouse effect) has always been associated with the increasing concentrations of carbon dioxide. Carbon, in the form of carbon dioxide, is a greenhouse gas released into the atmosphere as a direct result of human activities all the time. This in turn raises the temperature of the earth, leading to global climate change. The concentration of atmospheric CO₂ has already increased by about 30% since the beginning of the industrial revolution in the late 1800s. Most of this increase comes from using fossil fuel  coal, oil and natural gas for energy, but approximately 25 percent of the carbon came from changes in land use, such as the clearing of forests and the cultivation of soils for food production. Natural sources of atmospheric carbon include gases emitted by volcanoes, and respiration of living things. We breathe in oxygen, and breathe out carbon dioxide.

Scientists, engineers and planners are actively working to utilize and control the increasing concentration of CO₂ and have proposed many technologies and legislations in this regard. It is possible to reduce the amount of CO₂ released into the atmosphere by modern power plants by as much as 80-90% through carbon capture and storage technologies. The downside is that the fuel needs of a plant would increase by 10-40% in order to capture and store the carbon dioxide, thereby increasing operating costs by 30-60%. There are three basic ways to capture carbon. One is the remove it after burning fossil fuels, an approach that is already being used on a small scale by conventional power plants. Or the fossil fuel can be turned into a gas before the burning process and captured from the exhaust stream in a purer form of CO₂ and water vapor. A third emerging option is called chemical looping combustion, in which metal particles interact with the fuel and produce solid metal particles and a mix of CO₂ and water vapor than can be captured and transported to a storage site.

There are many alternatives for storing the captured CO₂. The most promising is storing the CO₂ deep in rocky formations in the earth, including oil and gas fields, and un-minable coal seams, using various trapping mechanisms to ensure the CO₂ doesn't escape back to the surface. In fact, injecting CO₂ into oil fields can increase oil recovery, thereby offsetting the extra cost of storage. Another option is ocean storage, in which CO₂ in injected deep into the ocean, where it dissolves, or deposited onto the ocean floor, where it is denser than water and therefore forms a "lake" of CO₂. The downside is that an excess of CO₂ in ocean waters increases acidification and can kill marine organisms. A third option is trapping the carbon in stable minerals permanently by reacting the CO₂ with metal oxides. But the reaction rate is slow. We need expensive pre-treatment to speed up the process, which would increase energy costs as much as 60-180%. Besides, they have discerned and confirmed the unforeseen advantages of rising carbon dioxide levels. Through the processes of photosynthesis and respiration, scientists have been able to elucidate why plants are growing more rapidly than they are dying. Too much carbon dioxide can be a bad thing, but sometimes it can have a positive effect on plants and trees. The more carbon emissions we dump into the air, the faster forests and plants grow. The answer may have more to do with how plants use CO₂. During photosynthesis, plants take in carbon dioxide from the air to make food, but as a plant decays, CO₂ is released back it into the air. The bad part is plants can't clean the air as fast as we are polluting it.

We do not think of ourselves as subsisting almost entirely on carbon dioxide  we eat meat, fruits and vegetables. But the animals we eat grew and lived on plants, typically grass. Likewise, fruits and vegetables are plants, as are the trees that cover the earth. And plants consume almost entirely carbon dioxide for food. It is true that humans, animals and plants require very small quantities of other essential material. We call ours vitamins and minerals. We call what the plants need nutrients or fertilizer. But while these materials are important, the quantities required are insignificant to life, compare to the carbon dioxide. So it is fair to say that the food used by all living things, to grow and to live, is carbon dioxide. People are incredibly ignorant of this fundamental fact  that food is carbon dioxide. The reason is that it has not been important until now. We do not consume carbon dioxide directly, do not go to the store and get. And, more importantly, when we grow plants we do not provide the carbon dioxide they consume. They take it out of the air. The food is free! We may work very hard to provide the water and the nutrients the plants need, as well as sunlight and protection from extreme temperature, but the food is free and we have nothing to do with providing it. So for millions of years people have grown and consumed plants and animals without knowing what they were eating. This fundamental fact was only discovered in modern times, and we still don't understand the process very well. Even today, most people have no idea that their food, and the food all the plants and animals that cover the earth, is carbon dioxide.

Carbon dioxide in the atmosphere is essential to life on earth and is directly responsible for the food we eat and the oxygen we breathe. Far from being a pollutant, rising atmospheric CO₂ concentrations will never directly harm human health, but will indirectly benefit humans in a number of ways.  Chief among these benefits is global food security.  People must have sufficient food, simply to sustain themselves; and the rise in the atmosphere's CO₂ concentration that has occurred since the inception of the Industrial Revolution (an increase of approximately 100 ppm) has done wonders for humanity in this regard.  And, it will continue to work wonders in helping us meet the rising food consumption needs of a larger, future population. In addition to increasing the quantity of food available for human consumption, the rising atmospheric CO₂ concentration is also increasing the quality of the foods we eat.  It significantly increases the quantity and potency of the many beneficial substances found in their tissues (such as the vitamin C concentration of citrus fruit), which ultimately make their way onto our dinner tables and into many of the medicines we take, improving our health and helping us better contend with the multitude of diseases and other maladies that regularly afflict us.  In just one species of spider lily, for example, enriching the air with CO₂ has led to the production of higher concentrations of several substances that have been demonstrated to be effective in fighting a number of human maladies, including leukemia, ovary sarcoma, melanoma, and brain, colon, lung and renal cancers, as well as Japanese encephalitis and yellow, dengue, Punta Tora and Rift Valley fevers. 

Aiding in the manufacture of food for the plant is not the only benefit from the extra carbon dioxide that becomes available from the soil microbes. Some of the carbon dioxide is absorbed by the water in the soil and forms carbonic acid. This carbonic acid dissolves some of the otherwise insoluble minerals the plant needs. The roots along with the water easily absorb the minerals. The result is a stronger, healthier, plant that requires less irrigation and is better able to withstand summer stress factors to which it is subjected. If the minerals are not available to the plant in adequate quantities, the plant will exert extra effort to absorb more water to satisfy its need for the minerals in question. This extra effort requires the plant to expend extra energy that stresses and weakens it over time. It also increases the plant’s need for water and decreases its drought tolerance.

The question of  is carbon dioxide comes up frequently these days because it's related to the global warming situation and to the effects of different activities on our personal and planetary environment - issues of great concern in today's world. But exactly what is carbon dioxide and how is it related to our health can be a little confusing when we hear about "carbon dioxide emissions" or "carbon dioxide pollution" because those terms convey a concept of something toxic.  Even hearing that carbon dioxide is a "greenhouse gas" somehow gives the impression that it might be "bad" for us.  Carbon dioxide has been part of the Earth's atmosphere apparently since it was formed kazillions of years ago. It's a natural chemical substance, primarily in gas form. It is not toxic unless in very intense quantities, which is rare at this time. The thing we can do is to continue to educate ourselves so we understand what carbon dioxide is and where it comes from  and support good solutions to having it to its optimum. Carbon dioxide is vital to both our personal health and to the health of our environment but too much of a good thing could create even more disastrous results than just the significant weather changes we've already started to experience.