The story of carbon dioxide
Slide 3: Plants make our food and oxygen! This slide shows more detail of the process plants use to make food and oxygen. CO2 and water enter the cells in the plant leaves. Sunlight shines on the leaves. Oxygen is released to the atmosphere. Food is retained in the leaf for the plant to use.
H. Douglas Lightfoot and Gerald Ratzer Slide 1: The story of CO2, the “gas of life”.
Slide 2: Plants make our food and oxygen. Plants take CO2 and water into their cells. Then, sunlight and chlorophyll, the green coloring matter, convert them into simple sugars and release oxygen to the atmosphere. The plant transforms the simple sugars into the parts we eat. These are leaves, stems, nuts, seeds, roots, and oils that we eat.
Slide 4: Plants grow faster at higher levels of CO2. Dr. Sherwood took this photo when the level of CO2 in the atmosphere was 385 ppm. Today, it is about 420 ppm. Increasing the level by 117% to 835 ppm doubled the height of the trees. The volume of needles and branches rose by three to four times. Commercial greenhouse owners control the CO2 level up to 1300 ppm to maximize growth rates.
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Slide 5: The Earth is greening because of increasing CO2. Satellites make it possible to see the increase in the area of the Earth where plants are growing.
Slide 7: Brontosaurus - large dinosaur. The CO2 levels and the corresponding significant growth rates were the norm during the period of the dinosaurs. These growth rates were necessary to feed the large animals.
Slide 6: CO2 and temperature: 600 million years. CO2 has been much higher in the past. It was during these higher levels that plants emerged and developed. This graph shows the estimated CO2 levels in purple and the temperature in blue.
Slide 8: Carbon cycle, billion tonnes carbon. Annually, vegetation absorbs 123 billion tonnes of CO2 and releases 120. The oceans absorb 101 billion tonnes and release 99 billion tonnes. Thus, 28%, or about one-quarter, of the CO2 in the atmosphere is recycled each year. The annual input of CO2 to the atmosphere was 9 billion tonnes at the date of this figure. It is higher now.
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Slide 9: CO2 measurements at Mauna Loa. The level of CO2 in the atmosphere is measured daily at Mauna Loa, Hawaii, and reported in ppm (parts per million). The location of Manua Loa is because it is far from significant sources of CO2.
Slide 11: The dynamic plant life. The last slide showed the dynamism of plant life. The Northern Hemisphere has two-thirds of the Earth’s land area. Therefore, its plants control the level of CO2 while producing oxygen. Plants in the ocean do their part and produce half the World’s oxygen. Why is there concern that CO2 is dangerously low?
Slide 10: CO2 measurements for two years. The vegetation absorbing and releasing CO2 annually became noticeable in the Northern Hemisphere when accurate measurements became available. From this graph, the difference in annual CO2 levels is 7 to 8 ppm. The annual increase in CO2 is 2 to 3 ppm.
Slide 12: Carbon dioxide: the “gas of life”. This slide shows the level of CO2 in the atmosphere for the past 160 million years. The level at which plants stop growing and die is 150 ppm. During the Ice Ages, the CO2 level dropped to 180 ppm—close to the lower limit. When plants die, all life on Earth will die. Life on Earth is close to being extinguished.
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Slide 13: Life in the Ocean depends on CO2. The ocean is where life is abundant in many forms. Many ocean creatures are air breathers, such as whales, dolphins, and seals. Those creatures that live below the surface are the most numerous and get their oxygen directly from the water. They release CO2 into water, thereby recycling it.
Slide 15: CO2 in nuclear submarines. Sailors spend months at a time at levels of CO2 substantially higher than the average atmospheric level. There does not appear to be any adverse effects. There is much experience with higher levels of CO2.
Slide 16: CO2 in the Space Station. Similarly to sailors in nuclear submarines, cosmonauts in the Space Station experience higher than normal levels of CO2 for months and years. There are no apparent ill effects. We are gaining experience with people exposed to higher levels of CO2 for periods of more than a year.
Slide 14: CO2 is not hazardous to our health. The American Conference of Governmental Industrial Hygienists (ACGIH) limits the 8-hour exposure limit to 5,000 ppm. The level can go as high as 30.000 ppm for ten minutes. The level in nuclear submarines averages 3500 ppm, ranging from 0 to 11,300 ppm. The Space Station limit is 5,250 ppm for 24 hours. We breathe out about 40,000 ppm. Each of us is a CO2 chimney.
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Slide 17: CO2 as a fire extinguisher. CO2 does not burn or react readily with anything. It displaces air around a fire and puts it out. ABC powder extinguished all three classes of fires. The powder releases CO2 that displaces the oxygen in the air and extinguishes the fire. Pure CO2 replaces the powder when a residue is unacceptable in “clean” locations.
Slide 19: Plants make our food and oxygen. Each of the cells in the leaves of a plant is a tiny chemical factory manufacturing oxygen and food. As the level of CO2 increases in the atmosphere, the small stomata need to open for less time to collect the necessary CO2. The leaves lose less water, and the plant can survive in dryer locations. That is one reason the earth is greening. Plants are beginning to move into the desert areas.
Slide 18: Combine CO2 with other chemicals. Combining with other chemicals is difficult to do because CO2 is so inert. It requires high pressure and temperature. Plants do not have this problem. They bring CO2 and water into the tiny cells in their leaves. Sunlight shining on the water and CO2 in the presence of chlorophyll, the green coloring matter, forms simple sugars. The plant uses these. This process results from millions of years of readily available materials and energy.
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Slide 20: Wood: Critical to development of mankind. Wood strengthens the stems of plants, especially the ones we know as trees and bushes. Wood was the first source of fuel for cooking and warmth. Wood is a widely used material for tools. Weapons for hunting for food and protection from animals and other people are well developed. Wood is still today an essential material for constructing houses and other structures. Transportation has always been necessary for human societies, and wood always had a vital role.
Slide 22: Carbon dioxide. CO2 is a gas that we cannot see, smell, taste, or feel. Yet, we cannot live without ample levels of it in the atmosphere of the Earth. If we could do something about the level of CO2 in the atmosphere, what should we do?
Slide 21: A coal-fired power plant. This coal-fired power plant's tall chimney emits invisible water vapor and CO2. At the top of the chimney, it takes a second or two for the water vapor to cool and condense into water droplets. The cooling tower emits pure, invisible water vapor that condenses into water droplets. The droplets of water soon evaporate. This year, 2023, coal consumption will reach a record high level. The developing world needs electricity to increase living standards, and coal is the "go-to fuel" to generate it.
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Slide 23: CO2 is a blessing! Celebrate it! Celebrate CO2! Our lives depend on it. Do not consider it a demon to destroy. CO2 is our friend. Do not bury it by carbon capture and storage (CCS). More CO2 is better for the lives of plants, people, animals, birds, and insects—all of which eat plants and breathe oxygen. How about a worldwide “CO2 Celebration Day?”
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