Carbon dioxide (CO2) is a relatively simple molecule, but a major part of climate change. It is a basic component of the world’s atmosphere that continues to increase with the number of humans, animals and machines exhaling it into the atmosphere.
April 2014 saw atmospheric carbon dioxide (CO2) in the Northern Hemisphere reach sustained levels above 400 parts per million (PPM) for the first time. Before the Industrial Revolution, levels are estimated to have been 240 PPM. The United Nations’ Intergovernmental Panel on Climate Change declared last month that CO2 must stay below 450PPM if the most catastrophic impacts of climate change are to be avoided.
The basics of carbon dioxide:
It is the most stable form of carbon. As such, it is key to nature’s carbon cycle. It is a colorless gas when at Earth temperatures, non-flammable and without scent. The molecule is made of two oxygen atoms and one carbon atom. At standard pressure and temperature (as established by the National Institute of Standards and Technology and others), CO2 is a gas. It is but a tiny fraction of everything in our atmosphere, but is nevertheless critical for all living things on Earth. Without it, humans would not have a breathing response. Nor would they have soda water, fire extinguishers, refrigerants, or decaffeinated coffee.
Carbon dioxide molecules are plentiful in outer space. They form after the explosions of supernovae in nebulae, the nurseries of our universe. It is very cold in space, of course, so interstellar carbon dioxide is solid, and unfathomable amounts of the stuff – what humans refer to as “dry ice” – float through the universe. When portions of nebulae form into planets, CO2 ice crystals become trapped and part of the various planets’ systems.
Venus is the most obvious example of our basic understanding of CO2-affected climate change / global warming / however it is being referred to today. Thanks to its out-of-control greenhouse effect, surface temperatures on Venus are hotter even than those on Mercury. Venus’ atmosphere is 97 percent CO2, which is responsible for daily temperatures of 480 – 600 Celsius (900 – 1,110 Fahrenheit). Venus has certainly experienced its own climate change epochs, a basic part of every planet’s history.
Carbon dioxide, the gas, becomes dry ice at -109.3 degrees Fahrenheit, much lower than the well-known 32 degrees Fahrenheit for water. Dry ice’s much lower temperature than water ice means that only half as much is needed to provide the same cooling. Unlike water, solid CO2 (dry ice) does not melt into a liquid, converting instead directly to gas. Because there is no liquid stage, dry ice does not leave a watery mess once it has “melted.”
The purpose of any living organism’s respiratory system is to exchange carbon dioxide and oxygen. Carbon dioxide arrives in the body through the air breathed. When CO2-carrying blood arrives in the lungs through the pulmonary artery, CO2 is released into the lungs and becomes the primary gas upon exhalation. A large amount of carbon dioxide – about 0.3 liter – is transferred out of the blood each minute.
Carbon dioxide is, of course, basic to climate change. But it is also interesting in its own right.
By Gregory Baskin