The following is from
the Liberty Energy “Bettering Human Lives” 2024 Report, page 98
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So long as agriculture was the primary source of human energy, including that harnessed from draft animals, the carbon cycle had annual flows and seasonal variations. Those organic flows continue today. During the Northern CO₂ & the Planet Hemisphere spring and summer, plant photosynthesis, using energy from sunlight, draws carbon dioxide (CO2) out of the atmosphere to combine with water to make chlorophyll – the basic building block of plant biology. In the fall and winter, photosynthesis drops dramatically, and plant decomposition returns CO2 to the atmosphere, completing the annual cycle.
Photosynthesis requires a minimum atmospheric CO2 concentration of around 0.015% (150 ppm). During the last glacial period (16,000 to 100,000 years ago), atmospheric CO2 nearly breached this level, falling to only 180 ppm. Before the large-scale use of coal, oil, and natural gas, from the seventeenth century onwards, CO2 concentration was estimated at just below 0.03%. The fossil-powered global economic growth since World War II has driven a steady climb in atmospheric CO2 concentration (shown in Figure 4.1) to slightly above 0.04% (420 ppm in 2023) as humans liberated the solar energy stored hundreds of millions of years ago in ancient plants (coal) and marine plankton (oil and natural gas).
Atmospheric CO2 concentration rises due to hydrocarbon combustion, which reverses the photosynthetic reaction in which oxygen combines with carbon. The equation represents the chemical reaction of burning methane, the simplest hydrocarbon. CH4+ 2O2‣ CO2+ 2H2O
One methane molecule reacts with two oxygen molecules to create one carbon dioxide molecule and two water molecules while liberating energy, primarily as heat, that can generate electricity, drive industrial processes, and home heating or be used for other life-enhancing endeavors. Carbon dioxide is plant food, and roughly half the CO2 released in this combustion reaction goes into the oceans or into “greening” the planet. Increased availability of CO2 in the atmosphere has led to increased agricultural productivity and a significant increase in global plant matter, grasses, trees, and plankton.